Designing a plug-and-go solution to expand the electric vehicle market

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INOM

EXAMENSARBETE ELEKTROTEKNIK, AVANCERAD NIVÅ, 30 HP

STOCKHOLM SVERIGE 2020,

Designing a plug-and-go solution to expand the electric vehicle

market

A field study in Kenya EDVIN GUÉRY

KTH

SKOLAN FÖR ELEKTROTEKNIK OCH DATAVETENSKAP

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Figure on front page. Example of a Toyota Land Cruiser in safari configuration, photo by (D'silva).

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Abstract

The transport sector stands for almost a quarter of the carbon emissions released into the atmosphere and is a sector where a lot of work remains to be done to mitigate climate change. To make a change quickly, the vehicles currently traveling the roads will need to be converted from internal combustion engine (ICE) driven vehicle to battery electric vehicles (BEV). The reduction in the use of fossil fuels will then have an immediately effect, which production of a new BEV does not, as otherwise the old ICE still stays on the road up until taken out of service. With a growth of economy in developing countries, such as Kenya, comes an expansion of the transport sector. It is very important to limit the negative environmental effect this may cause. One way to do this is to introduce electric vehicles.

Therefore, a field study was held in order to recognise the different demands put on a vehicle in the Kenyan national parks, a Toyota Land Cruiser in use of the safari business. From this, a drive drain design was established. To have a broader span of applicability, it was made with the thought of flexibility to expand production to other models and set a standard to work in the future. To achieve this flexibility, the drive train components were divided into different compartments. These compartments should fit together, forming the entire drive train. When converting different vehicles, different types of compartments can be fitted together to answer its specific needs. These compartments allow for a more modular product and can be easily adaptable when need be. The hope is that this way of installation can offer services to a wide range of vehicle models without having to make specific designs for every single one. With a growing number of electric vehicles on the roads, coupled with the high capacity of renewable energy sources found in Kenya, it has the potential to more become more self-reliant.

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Sammanfattning

Transportsektorn står för nästan en fjärdedel av de koldioxidutsläpp som släpps ut i atmosfären och är en sektor där mycket återstår att göra för att sakta ner klimatförändringarna. För att snabbt kunna se en effekt så måste fordon som för närvarande reser på vägarna omvandlas från förbränningsdrivna till batteridrivna fordon. Detta skulle ge en omedelbar minskning utav fossila bränslen, vilken produktion utav nya eldrivna fordon inte gör, då de fossildrivna fordonen I sådana fall skulle fortsättas att köras fram till dess att de tas ur funktion. Med den ekonomiska tillväxten som sker I ett flertal utvecklingsländer, likt Kenya, så tillkommer också en expansion utav transportsektorn. Det är viktigt att minimera de negativa effekterna som detta har på klimatet. Ett sätt att göra detta är med användning utav eldrivna fordon. Därför har en fältstudie genomfördes för att identifiera de olika kraven som ställs på ett fordon i de kenyanska nationalparkerna, en Toyota Land Cruiser I detta fall, som används inom safariindustrin. Från detta så designades en elektrisk drivlina. Men för att ha ett större tillämpningsområde så ansågs flexibilitet vara viktigt för att kunna utvidga produktionen till andra modeller och sätta en standard för framtida produktion. För att uppnå denna flexibilitet delades drivlinans olika komponenterna upp i olika moduler. Dessa moduler passar samman och bildar tillsammans hela drivlinan. Vid ombyggnad av olika fordon kan olika typer av moduler monteras ihop för att tillgodose dess specifika behov. Dessa moduler möjliggör en mer modulär produkt och kan lätt anpassas vid behov. Förhoppningen är att detta sätt att installera kan erbjuda tjänster till ett brett utbud av fordonsmodeller utan att behöva göra en specifik lösning för varje enskild modell. Men en ökning utav eldrivna fordon på vägarna och med en stor källa utav förnybara resurser så ser Kenya ut att ha vad som krävs att bli självförsörjande.

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Acknowledgement

I want first to thank Opibus Ltd for letting me work with them, making me feel welcome and giving me a place to stay during my time in Kenya. A special thanks to Filip Löfström, who acted as my handler at Opibus, for the freedom and trust I was given with my work. Secondly, I want to thank my supervisor at KTH, Mats Leksell for helping me through this work and coming with good feedback to make the best out of the report.

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List of Figures

Figure 1. Emission release of a lifetime of use from cars with different drivetrains (Helmers, 2020). 14

Figure 2. Load curve of Kenya Jan 25^th 2017 (Kenya vision 2030, 2018). ... 16

Figure 3. Electricity peak demand growth in Kenya (Kenya vision 2030, 2018). ... 18

Figure 4. Transport mode share of Nairobi (Fried, 2020). ... 19

Figure 5. Example of a Toyota Land Cruiser in safari configuration, photo by (D'silva). ... 20

Figure 6. Climate chart from Nakuru and Masai Mara national reserve (Ham, 2019). ... 22

Figure 7. Velocity that the vehicle has over the duration of the trip. ... 23

Figure 8. Elevation measured along the trip. ... 23

Figure 9. Power demand curve during the safari visit. ... 25

Figure 10. Two graphs showing the time and energy spent while moving versus the time spend standing still. ... 26

Figure 11. Emrax High Voltage with Combined Cooling, efficiency map (Emrax Innovative E-Motors, 2017). ... 27

Figure 12. Graph showing the number of cycles in comparison to the depth of discharge (Lithiumion- batteries, 2019). ... 29

Figure 13. Energy density of some of the most common battery types (Batteryuniversity, 2019). .... 30

Figure 14. Energy levels of the different cell sizes trying to match the different battery sizes. ... 32

Figure 15. Drivetrain compartments (Opibus, 2019). ... 33

Figure 16. Explode view of the final design of the front box, some components can be seen inside.. 35

Figure 17. Example of fuse box of same design. (Vander Haag's Inc., 2020)... 36

Figure 18. Right: Main conductor box, containing the BMS, DC/DC transformer and more. Left: Main conductor box inside the front box bottom part, next to the batteries. ... 38

Figure 19. A section view of the lid closing design, colored in red is the top box. Colored in blue is the bottom box, edging rubber in solid black. ... 38

Figure 20. Bosa 105Ah battery on the left and Narada 55Ah battery on the right. (Same number of cells inside the module). ... 39

Figure 21. Base of the front box, area containing the batteries. ... 40

Figure 22. Battery module designed together with Phoenix. ... 41

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List of tables

Table 1. Toyota Land Cruiser configured for safari use. ... 21

Table 2. The drag coefficients in different road conditions (HP Wizard, 2019). ... 21

Table 3. Electrical motor specifications (Emrax Innovative E-Motors, 2017). ... 27

Table 4. Controller specifications (Rinehart Motion Systems LLC, 2019). ... 28

Table 5. Drivetrain and system limitations. ... 28

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1. Introduction

The world is changing and what we once thought was a clean release of carbon dioxide into the atmosphere has now been identified as a threat to the climate as we know it (Gore, 2017). One of the biggest contributors to this problem is the transport sector, which stands for 23 percent of carbon emissions. This sector is well developed and implemented worldwide. Instead of decreasing, this number is set to increase by 60% in 2050 compared to the levels in 2015 (Marrakech Partnership for Global Climate Action, 2019). But a big part of the world that live in poverty, developing countries worldwide stand the challenge to have elimination of poverty and inequality as an overriding priority over climate change. As they develop, these countries are now starting to also use the well-known fossil fuel vehicles for transportation (Ebrahim, 2018). This means that the worldwide problem of pollution from the transport sector is only growing, as stated by the UN (Marrakech Partnership for Global Climate Action, 2019).

There are over 1 billion vehicles already out there on the roads all over the world which are consuming enormous amounts of fossil fuels every day (Voelcker, 2014). To switch all of them out for more sustainable vehicles would not only cost a fortune but also take a toll out of nature’s resources in the process. Another alternative is to do is to reuse the vehicles that are already out there but to exchange the source of the pollution, the old drive train which burns fossil fuels, with a more efficient and environmentally friendly system, an electric drive train.

1.1 Problem formulation

With the transport sector stuck in the use of fossil fuel, the increase in use of other means of transport must pick up the pace in order to answer climate change. This is where startup companies like Opibus Ltd comes in. They are converting old fossil driven vehicles into electric driven ones. They currently operate in Kenya, a growing economy in East Africa, and their procedure of converting a vehicle must go from a project-based to a line-based production to grow their production capacity. They also need the process and products to become standardized for more efficient use.

1.2 Aims and objectives

The assignment is therefore to oversee the vehicle at hand, a Toyota Land Cruiser used within the safari industry, and redesign the drive train setup and make sure it can be done in a functional line- based production. The aim of this thesis is to give a drive train design for the Toyota Land Cruisers which is adapted for a line-based production and improve the overall design to ensure robustness.

This design will then be used for future production in the coming years for Toyota Land Cruisers, but also act as a base concept to be adapted for other types of vehicles and models. It is to be an adaptable framework applicable to all kinds of other vehicles in the future.

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The problem can be summarized into the following questions:

• What energy requirements exists for this type of vehicle in East Africa?

• What battery system would be best suited for this type of vehicles?

• How to make the design compact and easy to produce and install?

1.3 Methodology

A literature study will be held to access the current situation on climate change and the transport sector. This will be done in hopes of identifying problems and what can be done to answer them. A relocation will be done to work directly in Kenya, it will last three months, and the work will be done together with Opibus Ltd stationed in Kenya to get a hands-on experience. A field study will be held, and a safari trip through Masai Mara will be taken to see, drive and experience the vehicles being converted. This field study will be used for collection of data and firsthand view of the conditions the vehicles are being put through. This data will then be used to get the restrictions on the batteries and to calculate the demand of power and energy requirements on these conditions. From this, a model will be set up where the collected data shall be put into and used to make the required calculations.

This model will then be used to set the specifications of the new vehicle drive train.

From these specifications, a set of components will be picked out to match the correct output needed from the motor with respect of the underlying conditions. This set will then have to be fit into the vehicle. This fitting design will be done in the computer program Solidworks CAD while always having a real version of the vehicle in the workshop to work with.

A set of milestones have been set up:

• Record a safari trip to inquire data.

• Simulate the demands of power and energy capacity.

• Design premade battery modules for easy assembly and robust setups.

• Verify the design, for all voltage levels, ampere limitations and heating restrictions.

• Specify front box ability to be preassembled.

• Have everything to be easily assembled and disassembled.

• Ensure IP67-standard.

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1.4 Limitations

Time and money are big limitations and the work done on the design has therefore been made in Solidworks CAD and no real product was ever made before I had to leave for Sweden (one prototype was sent for production as I left Kenya). The models made have a limited sample pool, the collection method only allowed for discrete data collection.

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2. Electric vehicles impact on climate change

The battery electric vehicle (BEV) has always been overshadowed by the internal combustion engine (ICE) as it has been too expensive to produce in comparison. But with a growing climate problem, the ICE has been shown to have a major problem in its emissions from the use of fossil fuels. With the BEV itself not having any emissions, the source of where the electric energy comes from must be looked upon. But with a growing knowledge and base of energy from renewable sources, the BEV offers something the ICE cannot, near to non-emission free driving.

2.1 Transportation from a global perspective

As of 2017, there was 1 million electric cars sold worldwide, increasing the total amount of electric cars sold up to 3 million (Petrauskiene, 2020). By 2014, there were over 1 billion vehicles in motion, meaning these few millions of electric cars is barely scratching the surface (Voelcker, 2014). This is a problem because of the damage vehicles which use internal combustion engines cause on the environment around them, such as pollution and noise. The pollutants released can include any of the following, SO2, NOx, CO, ozone as well as heavy metals such as mercury and particulate matter (Petrauskiene, 2020). These pollutants affect several systems and organs in a negative manner to both the human and the local environments health (Castanas, 2008). Noise which is caused by vehicles is also a major concern in close relation to human populations. In Europe for example, road traffic is the main source of environmental noise (European Environmental Agency, 2019). Electric vehicles on the other hand, do not have an internal combustion engine and thus do not emit any pollutants into the surrounding air. The Electric machine is also much more silent than the internal combustion engine.

However, the electricity, from which the electric vehicle gets its energy, must be produced in a renewable manner, or the problem of emissions has just been moved down the chain one step, polluting indirectly, instead of being solved.

The emissions released by the transport sector are increasing and is estimated to increase up to 80%

from 2007 to 2030 (Woodcock, 2009). One of the causes for this is the rapid growth of developing countries. In Kenya, a up and coming development country is a major player in this field, the need to be put on the right track towards a sustainable way of developing their transport systems from the start in order to reach the global goals of putting a spot to global warming. Current data says that greenhouse-gas emissions in development countries needs to be reduced by at least 80% before 2050 in order to be able to stay under the 2°C goal (Compassion, 2020). This number does not only include the transport sector, but it is still a major part in it. To go from the trend of increasing by 80% to a decrease of 80% is a big step and every little bit helps. In order to reach this goal, internal combustion engines need to disappear from the personal transportation sector by 2040 (Rinscheid, 2020). Several countries have planned to ban the sale of internal combustion engines by the year 2040 (Rinscheid, 2020), but that leaves all the vehicles still out on the roads. In order to exchange the existing vehicle armada that already exists, converting existing vehicles to electric is a way to avoid scrapping all the already existing vehicles driven by internal combustion engines. Then there is no need to reproduces all those vehicles, but just make changes to the already existing ones. This saves both money, time, and resources.

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2.2 Impact of converting to electric

Comparing battery electric vehicles (BEV) and internal combustion engine vehicles (ICEV) through life cycle analyses are important to get an environmental point of view at the impact of both these types of vehicles on human health, ecosystems, and planetary resources. In Lithuania, a study was held, making a prognosis of the years between 2015 and 2050 (Petrauskiene, 2020). The results showed that the BEV of 2015 around 43% more greenhouse gas emissions than a conventional ICEV during production. But in the year 2050, the BEV had 42% lesser impact than that of the ICEV. This, as well as the BEV of 2050 having a 52% lesser impact than that which the BEV had in 2015 thanks to improved electricity production (Petrauskiene, 2020). This shows an increased efficiency of the BEV over the course of time and that they are an investment for the future. But this study also shows that the BEV production of today is more costly for the environment than the ICEV at its initial manufacturing. This is why conversions of ICEVs can be a great opportunity to invest for the future at the same time it reduces the initial costs of the BEV as it takes the old chassis of the ICE and makes sure it is a more efficient solution for the coming future. Even though the vehicle looks the same from the outside, with the inside fully recycled, it will drive as new.

Other studies, looking at differences in lifecycle emissions of both ICEV and BEVs from today until the year 2050, similar results are drawn. In figure1, it can be seen that a ICEV and a BEV of today it not far apart on the life cycle emissions, while a BEV in the year 2050 has a drastically reduced climate impact from it’s used fuel (Helmers, 2020). The bottom two pillars symbolize an ICEV being converted into a BEV after half of its lifetime based on the two years of 2020 and 2050. It give a sense of view that converting a vehicle today may not have a high impact in itself, but that it would have an effect of reducing the remaining emissions by up to 50% when doing a midlife conversion. If the increase of lifespan of the vehicle is also taken into consideration the benefit is even higher. The electric mix of the fuel calculations are based on a European mix of 2020 and an estimated electric mix of Europe in 2050. The battery production is estimated to use a heavy coal based electric mix based on Chinas current situation (Helmers, 2020).

Figure 1. Emission release of a lifetime of use from cars with different drivetrains (Helmers, 2020).

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Batteries make up a big portion of the emissions during production process. The emissions released while using coal-based electricity have 3.8 times of a CO2-eq/kWh release compared to batteries made with electricity from wind power. In the figure above, the battery emissions have been calculated with the coal-based electricity. In the case of wind power, only 0.4% of the carbon footprint of the battery comes from the electricity of the production, which is negligible (Helmers, 2020). It is important to look at where and how the components are being produced and not only at the electricity fueling the vehicle to understand its final carbon emissions. In the figure above, it seems like they did only look over the use of a cleaner fuel but kept the production at the same emission rates. Hopefully, this will not be the case and the production can and will be made cleaner which will further improve the results.

Seen from a full life cycle perspective, an EV might pollute more in the initial production but assuming the ICEV have a lot of years left on the roads, converting to an EV is going to be the better option with regards to the climate (Helmers, 2020). With electric motors reaching an average efficiency of around 96%, they outclass the internal combustion engine which for lighter vehicles only reach the level of around 23% and due to the Carnot limit, the ICE will never reach the same levels of efficiency as the electric motor (Lombardi, 2020). It gives the motor the clear advantage in the vehicle as in the reduction of heat released and thus a reduction in its cooling needs. It also goes on less maintenance, there is no oil level that needs to be checked or refilled like the ICE do. This facilitates use and reduces risk of engine/motor failure from an inexperienced owner.

2.3 Economic complications

One reason the BEVs has always been in the shadows behind the ICE vehicles is the market price.

Vehicles with ICE drivetrains are much cheaper to produce and thus more appealing for the customer.

But in recent years, there has been several more affordable options released, together with the increase of taxes put on gas as a fuel (Abotalebi, 2019). This has opened doors for the BEVs. They are still commonly more expensive than their ICE equivalent but with a lower operation cost.

A study made across Toronto showed that BEV drivers where saving 1900$ per year in combined fuel and maintenance costs (Plug'n Drive, 2017). But even though savings can be made, the upfront costs still seems to scare people as shown from the low percentage of BEVs on the roads. Only 2% of Canadas market share are electric while a study of affordability suggests that 18% of Canadas households would see it as an economical investment (Abotalebi, 2019). This shows that even people living in rich countries are having problems looking over the initial costs while poor countries will have an even bigger problem. Therefor the initial price is still a critical factor when looking at BEVs.

With solar panels installed on the vehicle and care from the owner, the operational costs can be further reduced. Up to 50% of the daily distance traveled by an average U.S citizen could be traveled by using the energy from solar panels if installed over around half the projected horizontal surface of the vehicle (3.25m²on average) (Abdelhamid, 2016). This would offer further reductions in cost and environmental impact with the tradeoff in a further increased initial price. This potential can be beneficial for countries near the equator, having a strong solar irradiance, making the most out of the investment.

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2.3 Alternative use of electric vehicles

One problem with having the vehicle sector transfer over to being fully electric is the increase of stress it would put on the electric grid. If most vehicles start loading up on electricity instead as fuel, at a gas station the transmission would be an additive load onto the already existing network which in response then would need an expansion. But depending on how these vehicles are used, this might not be as big of a problem as it seems at first glance. Take the following example of the load curve from Kenya, as seen below in figure 2. The total load of society is not a fixed constant but goes up and down depending on what time of day it is. Naturally this goes up and down along the cycle of the day, with a morning ramp as people are waking up and going to work, followed a higher peak in the evening (Kenya vision 2030, 2018). In Kenya, this load curve looks mostly the same throughout the year as there is no real variation of temperature throughout the year and heating/cooling needs stays mostly the same.

Figure 2. Load curve of Kenya Jan 25^th 2017 (Kenya vision 2030, 2018).

The introduction of more electric vehicles could offer society a load shifting force that would help manage this curve rather than increase peak demand, if used correctly. By having vehicle-to-grid (V2G) solutions implemented into the vehicles, meaning they can not only get charged while connected to the grid, but also “charge the grid”, meaning they have the possibility to act as a load or a power source (Arias, 2020). Many of the vehicles are standing still during night, when their drivers are sleeping, and are on the roads mainly during the morning ramp and just before the evening peak. If the charging is left uncontrolled, many vehicles would get plugged in for charge as the ordinary person gets home from work at around peak demand and further add to that peak demand. But if controlled by a smart grid, the charge would only max out after midnight in the know that it is not to be used again before around 7am the next morning (Sufyan, 2020). This would then help in flattening the load curve of society and charge when demand is at a low, while offering to discharge during the day if the

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driver has accepted to offer their vehicle as a balancing force for the grid. The applicability here is immense and with good communication with the transmission operators could offer effective solutions and help to optimize the potential of certain renewable, but unpredictable energy sources such as for example wind and solar power (Sufyan, 2020). If implemented into a smart grid, they can act as frequency control for its quick response, wide availability (once a considerable amount of BEVs are on the streets) and ecofriendly response (Arias, 2020). This would also reduce pressure on ingoing electric lines to cities during these peak hours as the use of local energy sources of the vehicles rather than the need to import more energy from outside the city. The cost would be the need to refill the vehicles during nighttime, but as that is the time during the day which currently has the lowest load demand it would not pressure the system which is dimensioned after peak demand. By offering to use your own vehicle as the grids balancing tool, the personal benefit would come in as a payback per kWh, much like selling electricity from personal solar panels from home (Arias, 2020). But for all this to be a feasible solution, it requires to have a high enough systemwide capacity in the vehicle batteries as well as functional communication between the vehicle, the charging station, and the grid system operator. Therefore, conversions to electric vehicles are important to increase the pace at which this capacity can grow and make sure that these types of systems come into effect.

The V2G application does not limit it to big central grids but can also work within smaller microgrid with the right use of controller making sure you have the right frequency control as well as taking into account the battery lifetime by doing good predictions of the power use through the grid (Yang, 2020).

2.4 The need of renewable energy sources

In Chile, a study was held on the conversion of the public transport sector as well as taxis from ICEV to BEV. As 80% of the taxis were Nissan V16s and would need to be scrapped in the coming 5-8 years, converting them would end up giving them a second life (Girard, 2019). But in Chile this conversion would not result in any big changes in the released emissions if the electricity would be taken from the grid. It would only give a great effect if solar power was used to power these vehicles (Girard, 2019). This is because of how the electricity is produced in Chile, it is only a small part renewable and mostly based on combustion of coal and natural gases (IEA, 2019). If you instead look over to Kenya, their electricity production has a much higher percentage of renewable energy sources thanks to their geothermal facilities. These facilities, combined with the installed hydro power makes up for over 85%

of their electricity production (Netherlands Enterprise Agency, 2018). This gives grid-based charging for vehicles in Kenya an opportunity for great effect.

There are many advantages of driving an electric vehicle over the internal combustion engine, such as its simplicity, low maintenance, silent motor, and no release of any harmful gases. They have always been out shadowed by the ICEs cheap price. But as the fossil fuel prices are going up, both from the oil going scares as well as environmental taxes, the pricing issue is getting more complicated (Silva, 2019). This now opens up for electric vehicles to be cost effective solutions and with clean production of energy through hydro, geothermal, wind or be it solar also have a positive effect on the issue of global warming.

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With the clean energy produced in Kenya, thanks to their geothermal power plants, they have enough potential energy to power this electric conversion of their society. The year of 2016/17 they had a total generation of 10 205 GWh, with an installed capacity of 2 333 MW (Ministry of Energy, 2018).

The peak demand of the country laid at 1 656 MW, which is just slightly higher than the installed capacity of the renewable energy sources which lay at 1 530 MW (Ministry of Energy, 2018). So, at the moment the energy generated into the grid has the potential to be almost all but renewable. But Kenya is going through a major economic growth that is increasing the demand of power for every year that passes. During the last 10 years, Kenya have had an increase of grid-connected customers of up to 600%, and an increase of peak demand by 59% (Ministry of Energy, 2018). This is why they are having major plans on electrifying Kenya and to bring in an additional 5 000 MW of new generation by the year 2024 as they project the peak demand to stride up to 2 989 MW by the year of 2025 (Ministry of Energy, 2018). These are ambitious plans and show that the state is not holding anything back, they are looking forward. This energy would mainly be coming from new geothermal plants throughout Kenya as there are 14 high temperature locations along Rift Valley with an estimated potential of 10 000 MW waiting to be exploited (Ministry of Energy, 2018). When looking at the electrification of the public sector, matatus (small minibuses) is a key factor in making Kenya a sustainable country moving forward (Fried, 2020). With matatus being the main way of transport, part from walking around Nairobi, and it most likely staying that way for the growing economy which may increase the use of these vehicles as there is a lack of competitors in the transport sector (Jacqueline, 2019).

Figure 3. Electricity peak demand growth in Kenya (Kenya vision 2030, 2018).

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Figure 4. Transport mode share of Nairobi (Fried, 2020).

From figure 4, most of the paratransit vehicles are in fact matatus. It can be seen that people with low income mostly walk to work where some take the paratransit transports. What is interesting is that when the income increases, there is still both a high use of paratransit transports and walking being used. So even with an economic growth and an increase of wealth, the matatus will still be one of the main ways of transportation. With an increase of income, less people walk, but an equal amount of people keep taking the paratransit. Once a high enough income level is reached, a personal car is affordable but only used at a daily basis by around a 3^rd of the high income populous, with paratransits being the most commonly used (Fried, 2020).

From meetings between Opibus and the state of Kenya, they are very excited in the idea of the distribution of chargers around the city of Nairobi and in the electrification of matatus (Opibus, 2019).

With the right push, the owners seeing the long-term economic benefits of going electric, a Kenya driven by electricity has the chance to become a reality in the years to come.

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3. Energy Management

When looking at the question about battery size, as in how much electric energy the vehicle can store, it is important to look at what the vehicle will be used for and thus how much energy it would need.

As the current target group is the Toyota Landcruiser, used within the safari industry it is important to look on how the vehicles are used daily and when it has the opportunity for recharge. Therefor a field study has been carried out to figure out the energy needs to be stored on board the batteries.

3.1 Field study

The vehicle being looked upon in this case study is the Toyota Land Cruiser HZJ79 with a classic diesel engine to be reconfigured into an electric vehicle. It is a vehicle commonly used within the safari industry to transport tourists throughout different national parks in Kenya (Jenman African Safaris, 2019). In the following study, the park of Masai Mara national reserve has been used as reference as it was the location where the data collection took place. The study was done together with Opibus Ltd and their sister company Phoenix in France. The vehicle being used is not the exact vehicle in the figure 5, but the same model.

Figure 5. Example of a Toyota Land Cruiser in safari configuration, photo by (D'silva).

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3.1.1 Vehicle specifications

In table 1 are the specifications of the Toyota Land Cruiser which is configured for safari use. The roof is higher than a normal Land Cruiser and has an extended frame towards the back to fit extra seats, it can be seen in figure 5 above. When changing the engine to a motor there are several components that needs to be removed before the new drive train can be installed. This includes the main engine, fuel tanks, exhaust pipes, oil tanks etc. Some things are not entirely removed but must be partly disconnected like the gas pedal and break will be connected to the new motor control and thus rewired. This will not be looked into more closely in this report, just know that the mechanical steering system is not directly linked to the propulsion system and will remain the same. The main axis is kept but with a new motor to drive it. After the conversion is done, the weight of the vehicle will have changed, but with careful placement of components, such as batteries, the center of mass can remain the same. Here are the specifications of the vehicle in use.

Table 1. Toyota Land Cruiser configured for safari use.

Toyota Land Cruiser HZJ79 - Safari configuration

Gross weight (kg) 3800

Dimensions, Length, Width, Height (m) 6.00, 1.790, 2.33

Tire size (inch/m) 28/0.71

Internal Loads (W) 1000

Coefficient of Drag (Cd) 0.57

3.1.2 Conditions

As this study in taken out in Kenya, Masai Mara, there are a set of conditions regarding the surroundings that must be taken into consideration. The road conditions for one must be taken into consideration as it directly affects the driving in a major way. In this case it is not meant to drive around in towns but in the national parks of Kenya where nature is being preserved and therefore the roads are not covered in asphalt, they are plain earth roads. The vehicle is thus assumed to travel mostly on earth roads. These roads are at varying conditions dependent on the weather. Kenya do have rain seasons, but during these seasons the vehicles are not going into the wilderness and thus the dry earth road will be considered.

The driving conditions assumed to be on the average between larger off-road tractor tires and smaller

“tourism tires”. The drag coefficients used are stated in table 2 (HP Wizard, 2019).

Table 2. The drag coefficients in different road conditions (HP Wizard, 2019).

Driving conditions

Rolling resistance Sand Dry earth Gravel Wet earth Avg. Tractor/tourism 0.25 0.04 0.02 0.06

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The altitude and air pressure can also affect vehicles, but mainly if an internal combustion engine is being used and for the power calculations of electric motors, this will not be taken into consideration.

In Kenya, the temperature does not change much during the year, it stays rather stable at a minimum of 9°C (48°F) and can reach a maximum average of 28°C (82°F) during the period of January until Mars (Ham, 2019). This is a good thing because when designing the cooling system, the need for cooling will remain approximately the same throughout the entire year and thus not needed to be designed for that wide of a span of temperatures as in other parts of the world, as for example Sweden. The temperature is very important factor as it determines the size of cooling/heating needed. In order not to overheat converters or have batteries freeze, it is also important to keep the batteries away from extremely low (below 0°C) or extremely high (above 30°C) temperatures can be damaging for the batteries (Tomaszewska, 2019).

Figure 6. Climate chart from Nakuru and Masai Mara national reserve (Ham, 2019).

3.1.3 Data collection

A model is set up to calculate the energy demand of a standard trip using the safari vehicle. It is based on a trip in Masai Mara, Kenya, using one of the currently still diesel versions of the Toyota Land Cruisers during a day of representable conditions, sunny day in January of 25 degrees Celsius. Data collection is done using a GPS tracker which collects coordinates, average velocity, and altitude. The data was later transferred into an excel sheet. In total, around 500 measurement points where used in the following model.

The trip can be divided into three parts, where the first part is where the driver transports the tourists out into the reserve. The camps lay on the edge of the parks most of the time and the driver need to travel for a bit to reach the animals. This goes at a fast pace and thus requires higher amounts of power. The second part takes up most of the time in the park, here the vehicle is going at a slower pace as to give the tourists time to look at the landscape and wildlife as well as not to disturb the surroundings too much, it often includes a lot of stops and staying still as well. The third and last part of the driving is the trip back to the campsite, this is much like the first part as it goes at a higher pace and require more power from the motor. No matter the duration of the safari trip, the first and last

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parts stay mostly the same, what gets prolonged is the slow session of the second part which takes place inside the park. This means that a trip of double the duration does not require double the energy capacity. It is worth keeping in mind when making estimations for longer trips from this model rather short trip. The data retrieved can be seen in the figures below. From this data, the calculations to calculate the need of power and energy are made.

Figure 7. Velocity that the vehicle has over the duration of the trip.

Figure 8. Elevation measured along the trip.

0 5 10 15 20 25 30 35 40

0 2 3 5 6 7 9 10 12 13 15 16 18 19 21

Velocity (km/h)

Distance (km)

Velocity

1580 1600 1620 1640 1660 1680 1700

0 2 3 5 6 7 9 10 12 13 15 16 18 19 21

Altitude (m)

Distance (km)

Altitude

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3.1.4 Energy Calculations

From this data, together with the vehicle specifics and the environmental conditions a model was set up where the power the motor must commit to the journey was calculated. To do this, several factors must be considered, such as rolling resistance, air resistance, grading resistance and energy needed for acceleration as well as auxiliaries which need to be powered.

From the data that was available, some assumptions had to be made. Such as, assuming the roads to be flat and have one vector orthogonal towards the earth center of gravity, meaning the vehicle ever only tilts in the direction of the hill it is climbing and not to its sides. No acting wind is considered, nor any centripetal force from turning, only forces in one plane (in the sense of direction and latitude), thus no forces are acting on the sides of the vehicle as these are not known. From these assumptions, a model assumes that the vehicle is always going in a straight line. All data between the datapoint intervals is assumed to be linear between the last and the next point of data, this means slope angles and acceleration are assumed to be constant between the collected data points.

To get the total power needed to keep the vehicle in motion, the different forces acting on it must be known. By comparing the total force put on the vehicle and comparing this to the speed the vehicle is maintaining in its local environment, the power needed for this can then be extracted. The force that is needed to maintain the acceleration that the vehicle is under is a clear one, but it is not the only force acting on the vehicle, from the assumptions made above, there are other forces acting on the vehicle.

Air resistance has a major impact on the velocity of the vehicle. The aerodynamics of the vehicle play the part of the drag coefficient (𝐶_𝑑) and the frontal area of the vehicle (𝐴_𝑓). The air density plays a part, but it being ground vehicles it does not change too much. In this case, a constant air density has been chosen according to the air density at an altitude of 1650m.

𝐹_𝑤=1

2𝜌 ∙ 𝐶_𝑑∙ 𝐴_𝑓∙ 𝑣² (1)

The friction acting between the wheels and the ground can be seen in equation 2. The value of 𝑓_𝑟 (the rolling resistance coefficient) can be found in table 2 under dry earth.

𝐹_𝑟 = 𝑚 ∙ 𝑓_𝑟∙ 𝑔 ∙ cos 𝛼 (2)

The gravitational pull has been assumed to be equal at all points along the journey along with small- angle approximation saying it always acts on the vehicle in the angle of -90 degrees. The projection of the force onto the vehicles directional vector can be seen in equation 3.

𝐹_𝛼 = 𝑚 ∙ 𝑔 ∙ sin 𝛼 (3)

When taking these factors and forces into consideration, the average power output needed can be calculated between each datapoint. With the collected data of speed and elevation and commonly known data such as gravity and coefficients, the power required can be computed. The data points

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were gathered with at a fixed time interval and thus, the time is also known. The distance between each measured data point was then calculated by multiplying the average speed with the fixed time measured. With the angle of inclination gathered from the elevation data, the different forces acting on the vehicle can be calculated using the formulas above. These can be calculated into the power needed from the motor to provide enough force to counteract the sum on the other forces together.

To do this, multiplying the total directional forces with the average speed of the vehicle (𝑣). The motor does not have an efficiency of 100%, the required power must be divided by the efficiency of the motor (𝜂). The vehicle also has some auxiliary components draining power (𝑃_𝑎𝑢𝑥), these must also be added into the total power demand. While the power required is negative, the motor can act a generator. The efficiency of the motor/generator has been set to the same value. As these forces have been projected to act in the directional trajectory of the vehicle, they are no longer vectors but absolute values and can thus be added together.

𝑃 =𝑣(𝐹_𝑎+ 𝐹_𝑟+ 𝐹_𝑤+ 𝐹_𝛼)

𝜂 + 𝑃_𝑎𝑢𝑥 (4)

The efficiency of the motor was assumed to be constant as averages is what is searched for and not any exact or extreme values. From the data given above, the resulting power curve can be seen in the figure of 9. As can be seen in the power output, the power goes below zero at some point. In this case the motor can act generator and charge the batteries.

Figure 9. Power demand curve during the safari visit.

-20 -10 0 10 20 30 40 50

0 2 3 5 6 7 9 10 12 13 15 16 18 19 21

Power (kW)

Distance (km)

Power curve

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To then convert this power demand into a total energy demand of the vehicle, the summed energy demand from each data point multiplied by the time difference between them to arrive at the total energy required. As seen in the two graphs below, the result from this short 2 to 3-hour trip resulted in an energy consumption of 13,76 kWh. A lot of the time the car is staying still while letting tourists take photos, this has been dismissed in the power diagram above. This shows that the vehicle consumes little energy for the amount of time it is in service and does therefor not require enormous battery storages onboard the vehicle even though the car is heavy and are traveling in rough terrain as it often keeps a low speed. A standard safari trip is normally about 6 hours long, where 4 hours of the visit are being spent in the park (Ham, 2019). This means 2 hours of fast pace driving to and from the park and 4 hours of slow pace driving with a lot of stops while in the park. Scaling the results to this type of trip would result in an energy consumption nearing up to 30 kWh.

𝐽_{𝑡𝑜𝑡𝑎𝑙} = ∑ (𝑃_𝑘∙ 𝑣_𝑘∙ 𝑡_𝑘)

𝑘=𝑁−1

𝑘=1

, 𝑁 = 𝑡𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑑𝑎𝑡𝑎 𝑝𝑜𝑖𝑛𝑡𝑠 (5)

Figure 10. Two graphs showing the time and energy spent while moving versus the time spend standing still.

From this information, an electric motor was chosen. There were several factors to consider, but it came down to the right power dimensions, the price and how compact it was. With a maximum power output demand of around 40 kW during the modeled drive, it was concluded to have a maximum output of around 100 kW. The model only calculated averages and it is only suited to get the continued power output, not the maximum. As most of these terrains are rough, the drivers may sometimes need a high peak power to get out of a tough situation. The specifications of the motor can be seen in table 3.

0 0,5 1 1,5 2

Moving Still

Time (h)

Time

0 2 4 6 8 10 12 14

Moving Still

Energy (kWh)

Energy

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Table 3. Electrical motor specifications (Emrax Innovative E-Motors, 2017).

Electrical motor specifications

Manufacturer and model Enstroj, Emrax 228 MV

Peak power (kW) 100

Peak torque (nm) 240

Motor efficiency (%) 92-98

Max RPM 5500

Operating temperature (min, max, °C) -30, 120

Cooling AC/LC/CC

Inlet water flow (or coolant) 8 l/min Water (or coolant) flow temperature (°C) 50 Water (or coolant) flow pressure/drop (bar) 0.9

The motor efficiency is rather complex and depending on multiple conditions. The manufacturer provides the following figure below for a more exact estimation of the efficiency. The map is stated to be for the high voltage motor but is valid for all the voltage levels. It was chosen to be set as a constant for the sake of the model as the data collection was not accurate enough to be able to track the torque and motor speed and thus not pinpoint the exact efficiency at all times.

Figure 11. Emrax High Voltage with Combined Cooling, efficiency map (Emrax Innovative E-Motors, 2017).

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The controller was chosen with the consideration of matching the motor as it acts as the power inverter linking the batteries to the motor and voltage levels are very important here.

Table 4. Controller specifications (Rinehart Motion Systems LLC, 2019).

Controller specifications

Manufacturer and model RMS, RM100 Propulsion Inverters Maximum battery voltage (V) 450

Maximum motor phase current (A) 300 Operating temperature (min, max, °C) -20, 65

Efficiency (%) >97

Cooling system Pipes for liquid cooling, no flow/temp specs

The controller and motor specifications together set up the system limits according to the table 5.

These limits together with the data from the model are then used to dimension the battery system.

Table 5. Drivetrain and system limitations.

Drivetrain and system specifications Maximum voltage (V) 450 Maximum current (A) 300

Maximum power (kW) 100

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3.2 Battery capacity

To just put the battery to the size of the demand is bad on several levels. Every trip is different in length and extra energy is always welcome. Something very important when using batteries, is the depth of discharge. A battery degrades over time and the more it is used the more it degrades, but it also depends on how it is being used. Depending on by how much the battery is depleted and at which pace, the number of cycles the battery lives for changes. The deeper and faster the battery is being discharged, the fewer charge/discharge cycles the battery can handle and the sooner it will need to be exchanged for a new one. To maximize the lifespan of the battery pack, the pack should always be dimensioned to take in account the depth of discharge (Tomaszewska, 2019).

Figure 12. Graph showing the number of cycles in comparison to the depth of discharge (Lithiumion-batteries, 2019).

The way to increase the number of cycles and thus its lifeline is to increase the battery size and therefor decrease the percentage of the battery being discharged. This on the other hand mean that the battery is bigger than needed which comes at the cost of a more expensive battery as well as more added weight to the vehicle. Often the 80% depth of discharge is used as a good balance between lifetime cycles and battery size and cost (Rushworth, 2015). Using this on our 30kWh demand would set us up to a 37.5 kWh battery system for the vehicle. This would then set the standard of reaching 80% depth of discharge after a 6 hours standard trip and still have some energy left to get home even in the case if anything unusual would happen (Rushworth, 2015).

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3.2.1 Battery chemistry

There are several types of chemistry with different characteristics. Most of the batteries looked upon when regarding the subject of electric vehicles are Lithium-ion batteries as they offer a constant energy capacity at different current flow (Rushworth, 2015). Batteries which like Lead acids do not have the same effect then delivers less capacity at higher current flows. This is especially important in electric vehicles because the current is ever changing depending on the motors power demand (Lithiumion-batteries, 2019). The most common types used for EV-applications can be summarized to the following (EVInnovate, 2017).

• Lithium Cobalt Oxide, LiCoO2. It is mainly used in consumer electronics and technique of the classical 18650 cylindrical cell. Stable and high energy density. However, subject to overheating, outgassing and thermal runaway.

• Lithium Iron Phosphate, LiFePO⁴. It has lower capacity compared to other Li-ion chemistries but is more stable from a safety perspective and does not overheat or thermal runaway to the same extent. Up to five times longer lifespan than other alternatives, but higher cost.

• Lithium Manganese Oxide, LiMn2O4. An inexpensive option that allows for high rate of charging, but lower energy density.

Figure 13. Energy density of some of the most common battery types (Batteryuniversity, 2019).

When comparing these techniques, you need to consider what application the vehicle is going to be used for. Electric vehicles are meant to last and be used for long periods of time, and therefore the number of cycles is often one of the better ways to prioritize over energy density or maximum discharge rate. Because of the amounts of lifespan cycles and safety/stability-measures the optimal battery chemistry to be used for the application in this report is Lithium Phosphate.

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As a note, the temperature at which these batteries will be operating is in an environment of around 24° Celsius (Ham, 2019). Kenya, as said before, have a very steady ambient temperature throughout the year with minimal changes. This is optimal for the batteries as they can suffer from it being too cold or too hot (Battery University, 2017). With Li-ion having problems charging when under 0°C, this would mean it needs heating while charging at sub-zero temperatures. If the ambient temperature is above 50°C, then extra caution would need to be implemented. But operating at the around the 24°C mark it will only need a smaller amount of cooling with focus on the performance rather than the ambient temperature.

Prices are always a big factor to take into consideration. Batteries are the reason why electric vehicles are as expensive as they are. The batteries make up a big part of the costs for doing a conversion. This makes it important that the price given by a supplier to be as low as possible. Making the tradeoff answering the demands in the best way possible and the cheapest way is what makes or breaks a solution. When dealing with developing countries like Kenya, it is extra important, as budgets can be extra tight. Having an affordable solution is key but it must also deliver what is asked of it.

3.2.2 Battery design

The chosen controller is working with a voltage of maximum 400 Volt and the motor and converters are all dimensioned around it. Therefor it is important to keep the voltage under that limit to ensure the safety of the internal components of the vehicle.

From the different Battery suppliers, Narada is the one who won out in the end for having the energy dense batteries both in sense of volume and weight, available at a reasonable price. But not only choosing a supplier but also which one of the different battery cell sizes. With a range of cell sizes from 55-105 Ah, there are a lot of factors to take in. When looking at the battery architecture the voltage limit becomes a limiting factor. The total voltage of the battery pack is the total number of cells in series times the cell voltage. In this case, there are 108 cells in series and the maximum cell voltage is at 3.65 V which gives us a voltage of 394 V. This voltage level has been chosen to work around as it is high enough to keep the amperes flowing through the cables to not rise too high but also low enough to make sure it is a reachable level in the number of batteries in series needed. The cells are being modeled in groups of 12 cells in series to go together with the Orion BMS2 which monitors the batteries. That is why the number of 108 cells was chosen. It is also good to keep a safety distance in the voltage range between the maximum reached by the batteries and the limit (450 V) at which the components connected to it are meant to operate. This voltage is only achieved at 100%

state of charge (SOC), during most operation, the cell voltage is at 3,2V and thus the battery operating voltage at around 345V.

The three sizes of batteries chosen to be looked at are the 55Ah, 80Ah and 105Ah to see which one would make the best fit for the vehicle, one small, one medium and one large sized cell. The cost is a non-factor as the prices per Ah is the same across the board within this company. In the table below is the required configurations to achieve the 394,2 V at 100%SOC (108 cells in series) for the different desired pack sizes of 30, 50 and 70 kWh which would represent a short trip, medium trip and full day trip with the safari vehicle without any need of charging.

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Figure 14. Energy levels of the different cell sizes trying to match the different battery sizes.

As seen in figure 14, the different packs do not always match the desired outcome and the size of each individual cell becomes a problem. The 80Ah battery choice was ruled out quickly as it cannot match the 30kWh without exceeding the limiting voltage and if chosen to put as parallel couplings to half the voltage brings it up to 55 kWh which then makes it a excluded from the 30 kWh version. The same way the 105 Ah one cannot come close to the 50kWh model. Only the 55Ah batteries are small enough to model after desire and match all three pack sizes while matching the desired voltage levels. Having a little excess energy in the tank provides insurance that the vehicle can be used for the desired amount, may it be 30, 50 or 70 kWh, and still range in the 80% DOD range (Rushworth, 2015).

The 105Ah ones are the most energy dense batteries they have, the problem with it is that each cell is bigger than the smaller models and therefor hard to fit when converting a car in which you have a limited design capability. The 55Ah batteries are much more flexible in that way that they are easier to fit into any vehicle model, but you need almost the double amount of cells to achieve the same amount of capacity, and with them being less energy dense they take up more volume. But because the design have to fit a vehicle designed which was originally designed with a different purpose in mind (being a diesel fueled vehicle), the smaller 55Ah modules are easier to fit and the space that is available can be used to a larger extent they still offer a more space efficient solution.

That is why the 55Ah cells were chosen as the one to continue working with as they offer a lot of flexibility in their small module size and therefor able to fit better physically as well as capacity wise as they can be linked in different ways inside each module to adapt to any of the three options of packs, 30, 50, 70 kWh. The Exact pack capacity is always higher because of the negative effect on the number of cycles the batteries can live through before getting worn out if always fully discharged.

30 kWh 50 kWh 70 kWh

55 Ah 38 57 76

80 Ah 28 55 83

105 Ah 36 36 73

0 10 20 30 40 50 60 70 80 90

Battery matching

55 Ah 80 Ah 105 Ah

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4. Drivetrain design

The separate components of the drive train, such as the motor, the controller, and batteries, must be organized in such a way that the goals of the installation can be achieved. These goals were for the drive train to be adaptable, able to be prebuilt and for the process to be standardized. This would then give a modular product with the ability to be customized after the customer’s order without having to come up with a new design, but rather be put together thanks to premade modules to match the customer’s needs. The different important sections will be gone through accordingly.

4.1 Overall layout

The battery packs have been designed after the specifications given by the other components running the drive train, such as the Reinhart controller which in turn powers the electric motor, the on-board charger (OBC) and the DC/DC converter which powers the 12V auxiliaries.

The drivetrain is built up out of several segments. The new electric motor is in the front of the vehicle, connected to the same axis the old combustion engine used to be attached to. With the new motor, being much smaller than the old engine, it leaves a lot of space in the front compartment which is used to store several other components vital to the operation of the motor as well as the batteries.

But for vehicles of this size, storing of all the batteries in the front compartment does not give enough energy, thus one box in the center or even in the back of the vehicle is needed in case of a higher energy demand in order to give the vehicle a longer range of operation.

A big problem with converting old vehicles into electric is that each vehicle is different, and in such the inner workings of the vehicle is different. This makes it so each vehicle needs a unique solution and therefor makes it a long and costly experience to make such conversions. But this is what this drivetrain redesign is trying to tackle. It is originally made for Toyota Land cruisers but with the thought of flexibility and adaptability in mind to be applied onto other vehicle models. The hope is that this flexibility then can increase efficiency of the workflow when dealing with different types of vehicles.

Figure 15. Drivetrain compartments (Opibus, 2019).

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• The vehicles spend too much time in the workshop.

• New unique design required for each new vehicle.

• Assembly is done directly into the vehicle.

• Components risk failing during assembly.

• Batteries needs to be more stable, shock proof.

The first three of the problems had to do with the time, it takes to do with time to assemble the new configuration. When the components are installed into the vehicle, they may risk failing and thus increase the assembly time when new components must be brought in. When every vehicle is a little different, new designs are made all the time and nothing is standardized. This takes time for both designers as well as for the workers to learn the new set up each time.

The fourth point is about how it is assembled, it is assembled straight into the vehicle, peace by peace.

Meaning it is a hassle in order to reach correctly and vision is restricted. This makes assembly trickier than it should be. By splitting up the work into smaller standardized tasks, it establishes a basis for continuous improvement.

The fifth point is looking at how the batteries can be made more solid, as there have been some problems with the batteries at times. This is very important as it is what powers the motor and makes the vehicles tires spin. Thus, a high priority on batteries have been set for this project and on how to make that configuration safe and steady.

The idea was to make sure as much as possible could fit into one box solution, with as few outgoing plugs as possible. This way the box could be premade outside the vehicle with both greater ease and saving a lot of time while ensuring everything works at the time of installation. This way, once the box is underneath the hood, with only a few cables to attach in order to make the vehicle start rolling. This would then allow to have done drivetrain boxes waiting for a vehicle and allow for much quicker delivery times for the customer as most of the job would already have been done prior to the order.

A plug and play solution.

This box, the front box as it is referred to, which sits in the front of the vehicle, contains most vital components to the electric drive train. This is where the limitation of space comes into play and its ability to fit into several different models of the Toyota Land Cruiser which differs a little between the models. Thus, the Land Cruiser model chosen is one of the smallest one normally encountered on the market.

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4.2 Front box

This is the compartment that contains most vital components to make sure the motor runs as it should.

It is in the front of the vehicle where the old internal combustion engine once was. As it protects sensitive components it is important that is holds the IP67 standards to prevent any water from leaking in, even in the case of being submerged under water. During the rainy season in Kenya there is a high risk of flooding in large parts of the country and therefore it is important that the vehicles can still be operational even during these times of the year. From the problems which the old assembly had, this front box, shown in the figure below, was designed to act as the one-box solution which is easy to install and possible to prebuild in a number of sub-assemblies to later be installed into the vehicle as one simple box with as few exterior connections as possible.

The box was chosen to be divided into four main parts. Part one is the bottom box which holds the batteries as well as part two which is a smaller box containing the BMS, the DC/DC converter, the main conductor, the main fuse, pre-charge conductors and the main switch. Part three and four is the top box which is divided into two different parts. One, containing the fuse box, a smaller 5V transformer and space saved for a planned integration of a vehicle computer unit (VCU). The other part of the top box is not fully closed and thus not IP67 classified. But as it contains the Reinhart controller and the on-board charger which are both IP67 certified themselves, there is no need for further protection against water, they can thus be more open and benefit more from ambient cooling. The decision to split the front box and its components into smaller parts was to be able to make them separately for later interconnection. This allows for easier subassemblies and troubleshooting before putting it all together. The components inside are grouped in order to minimize the connection between the different box parts and thus minimize cabling.

Figure 16. Explode view of the final design of the front box, some components can be seen inside.

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The upper box was made to work as a lid for the bottom box and sits on hinges. This decision was made to make it easy to access the bottom box in order to fix anything in case of a malfunction. To be able to keep the IP67 and correctly protect the batteries, making the enclosure is watertight is extra important. Cabling between the two boxes is done on the left side protected in a harness which leads to the back where the hinges are located, allowing to open the lid without putting stress on any of the cables going between the top and bottom box.

4.3 Fuse box redesign

There was need for a functional fuse box available for owner of the vehicle to be able to interact with in a simple way. It was currently an exterior compartment, separate from the front box itself, with the design purpose to refit as much as possible into one unit it had to go into the front box, this would reduce exterior cabling, making it less prone to damage and thus more safe. This would then also free up exterior space to make installation as well as later modifications easier. The second goal here was to make the fuse box more accessible by the customer in case of a fuse or relay failure. Before, the fuse box was bolted shut, and the inside not user friendly. This could easily be fixed with a commonly used variant, a simple plastic frame which holds the fuses on top and hides all the cables on the underneath the frame. This then makes it look neat and is easy to use for the customer. The setup shown in figure 15 is an example how it looks in a different case to give a picture of the idea.

Figure 17. Example of fuse box of same design. (Vander Haag's Inc., 2020)

Designing a plug-and-go solution to expand the electric vehicle market

Designing a plug-and-go solution to expand the electric vehicle

market

A field study in Kenya EDVIN GUÉRY

Abstract

Sammanfattning

Acknowledgement

Table of Contents

List of Figures

List of tables

1. Introduction

1.1 Problem formulation

1.2 Aims and objectives

1.3 Methodology

1.4 Limitations

2. Electric vehicles impact on climate change

2.1 Transportation from a global perspective

2.2 Impact of converting to electric

2.3 Economic complications

2.3 Alternative use of electric vehicles

2.4 The need of renewable energy sources

3. Energy Management

3.1 Field study

3.1.1 Vehicle specifications

3.1.2 Conditions

3.1.3 Data collection

Velocity

Altitude

3.1.4 Energy Calculations

Power curve

Time (h)

Energy (kWh)

3.2 Battery capacity

3.2.1 Battery chemistry

3.2.2 Battery design

Battery matching

4. Drivetrain design

4.1 Overall layout

4.2 Front box

4.3 Fuse box redesign