Conversion
Example for a conversion in Hungary:
Conversion of a Citroen 2CV to electric
Decision
In 1994 I have bought a then 12-year-old Citroen 2CV, on its popular name: a "Duck". During a serious renovation it has got a new and stronger chassis, its body has been repaired from the rusty parts and its motor has been renewed. In addition the whole exhausting system, the shock absorption system and the canvas hood have been replaced and the inner parts have got new textiles. The total cost of this renovation was about 4.000,- EURO, but it was worth. Our "Duck" would be so unique and so nice that everybody from the family and the city was admiring it. The next 12 years we have kept this car in a garage and have been used as the second car of the family only for short trips: we took our children to kindergarten and to school with this car and used to make shoppings with it. The car was running about 3-4.000 km per year. I started to be interested in using electric motors in 2006. The electric motors are much more suitable for such purposes than the benzin motors.
Looking around on the internet I have experienced that I am not alone. Many people, mainly in the Anglo-Saxon countries, first of all in the USA have already made such conversions.
To serve those people undertaking converting their car there are a number of webshops on the internet, too. Studying the choice it became obvious that all the base conversion kits are using carbon-brushed DC series motors. Of course better, more up-to-date and more efficient motors can be found, too. But the price of these motors are much higher than I was thinking of.
Starting-base
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| The little duck | Canvas hood open | |
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| Motor space | Passenger's space |
Taking to pieces
The simpliest task was to take the unneeded parts out of the car. The benzin-motor, the exhausting system, the benzin tank, the self-starter, the generator and the parts of the heating system have been got out of the car.
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| The old benzin-motor has been got out | and every unneeded part, too | |
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| giving place to the new motor | The gear-box remained on its place |
Only the gear-box remained in the emptied motor-space. The parts coming out of the car were sold on an internet flea market (www.vatera.hu).
The motor
The newly installed motor is a simple carbon-brush DC series motor. You can find some informations on the next page about how these motors are working: http://en.wikipedia.org/wiki/Brushed_DC_Electric_Motor . The data sheet of the motor can be found on the next page: http://www.evpermanent.com/katalog/dct7kw5_72.pdf . To install the motor the appropriate fitting-strip and the motor holder have to be made.
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| "Coupler" | The fitting-strip | |
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| The place of the new motor | The new electric motor yet outside | |
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| The electric motor on its place | The new motor already connected with the cables |
You can see on the pictures that I tried to make closed the originally open motor-space. This was possible because the electric motor does not need intensive cooling, its efficiency is about 80% opposite to the 10-15% working efficiency of the benzin-motor. The solely attritioning parts in the motor are the carbon-brushes. They have to be exchanged every 30.000 km.
The controlling electronics
To control a series DC motor is very simple. You have to switch the power supply on the motor for different times. This controlling is called PWM (Pulse Width Modulation) or chopper controlling. We interrupt the electric circuit 15-20 thousand times per seconds (15-20kHz). We control the required power output with changing the rate of the switching on and the interruption. As we have to switch more hundreds of Amps, we have to use appropriate high-current semi-conductors. I have installed a factory controller into the eDuck. The pedal makes the controlling with a HALL-sensor. The controller together with the main relay and the shunt resistor of current measuring have been put into the motor-space. Onto the same place is installed the current-pedal. The new current-pedal is bound with a steel wire to the accelerator pedal, so the original pedal-placing remained unchanged.
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| The motor controller | The controller in the motor-space | |
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| The controller already installed | The new pedal installed into the motor-space bound with a steel wire to the original accelerator pedal |
The battery pack
I have installed lead acid gel batteries. These batteries, as they are fully closed, can be installed directly into the passenger's space. In my case the 6 pieces of 12V/120Ah batteries were put onto the place of the back seats. (The back seat was taken out of the car.) The intelligent charger connecting to these batteries has got place under the right front seat. The connection to the net I could resolve with a self-winding cable-drum coming out of a vac-cleaner. To connect the batteries to the controller and to the motor I have used a 50 mm² twisted copper wire.
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| The battery pack | The cable-drum | |
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| The controller under the right front seat | 50 mm² cable |
The gear-box
The vehicle is at once ready for working just after the installation of the motor, the controller and the battery pack. The installed motor can give down its highest power rate (7.5kW) on 2800rpm. On higher rpm the given down power rate diminishes. (On slower rpm the given down power rate increases.) The original benzin-motor of the Duck gives down its higher power rate on 5750 rpm. For this reason the gear of the Duck was designed to present about 50km/h in the 4th gear at 2800 rpm. To reach this speed it is enough 4-5kW motor power rate. If I would install only a 4kW electric motor into the Duck, the original gear would be ideal to reach the 50-60km/h end-speed. But I wanted more of that, that's why I have changed the transmission in the 1st, 2nd and 3rd gears from 25:13 to 18:20. I could reach so that 86km/h belongs to the 2800rpm in the 3rd gear. As a result of the conversion I had to renounce the 4th gear. This is not a big loss because the electric motor is much more elastic than the original benzin-motor. In average circumstances I have to use only the 2nd and 3rd gears. The 1st gear I have to use only when starting on bigger than 15% slope with the car.
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| The cancel-cog-wheel pair is marked | The exchanged cog-wheel pair: up the new - down the old |
The measuring instruments
Because of changing the original transmission rate the speedometer did not show the right values. For this reason I have altered it to a simple 2-digit LED speed-measuring. I measure the temporary current consumption on a 300A shunt with a little analogue measuring instrument. The voltage of the batteries I measure with an analogue measuring instrument as well.
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| The new speedometer | The current and voltage meters |
The usage
With one word: experience! A little more abundantly: delightful experience! Of course as it is an electric vehicle there are two questions which I am always asked first:
- How much is the end speed? Answer: on plain roads 75-80 km/h, on serious slopes 60-65 km/h.
- How big distance it can take with one full charge? Answer: in summer 50-60 km, in winter 30-40 km.
Of course there are many people who find these two datas too little. We have to take notice that the electric vehicle cannot replace the cars working with fluid fuel in each aspect. But in cities for short distances it is an environment-friend and cheap conveyance. The dinamics of marching is not worse than at the fluid fuel motors until 50km/h due to the elastic and big emphasis of the electric motor. The total consumption including the losses, into which I count the losses of the batteries and the charger, too, is about 150-175Wh/km. For this energy I have to pay only 0.012 EURO/km if I am "fuelling" from the switched net. (If you count how much you pay for 1 km with 8 litres/100km consumtion you will get more than 0.08 EURO/km - the amount depends on the country.) For environment-friendlyness many people says as counter-argument that big rate of the electric power is made from burning fossile energy sourceswhich has losses during producing and transportation as well. And the total efficiency of using the energy is not better than in the case of fluid fuel motors. More studies have showed that the efficiency of energy usage is about 1.5-2 times as good in the case of electric vehicles than in the case of cars having combustion engine. You have to take into consideration that a significant part of the electric energy is made of renewable energy sources (water, wind, solar) or nuclear energy. It is especially true for the consumer's valley period. The biggest problem for the energy suppliers in this period is that they cannot do anything with the excess production of electric energy coming from nuclear reactors and renewable energy sources. To store these quantities could be a good chance by the increasing volume of electric vehicles. To use more and more electric vehicle could increase the proportion of energy producing from renewable energy sources. The biggest difficulties in this matter are that the production cannot be planned in time.
The only disadvantage of using electric vehicle for me was the missing of noise. The other participants of the traffic do not "hear" me coming, they do not percieve the speed. I have to be especially careful of pedestrians not to become a "silent killer".
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