## Thoughts before Conversion

We have to talk about some important questions before starting the conversion :

#### What should we like to use our electric car for?

You have to notice that a merely electric vehicle cannot substitute a vehicle using fossile fuel in each aspect considering the up-to-date technical possibilities.

### Limitations:

1. ##### Effective distance
2. The most important limiting factor is storing the energy. The mostly widespread and cheap lead acid batteries can store 30Wh energy in 1kg. Even the energy density of the lythium based batteries is not more than 100÷150 Wh/kg oppose that value of 12.000 Wh/kg for the gasoline. If we should like to carry with ourselves the energy quantity stored in an avarage fuel tank during the whole way we should need about 5 tons of lythium batteries, from lead acid batteries this weight would be three times as much. In the reality the situation is not so dark. The efficiency of electric motor is much better than that of cars installed with gasoline motors. The consumption of an avarage converted vehicle is about 10÷15.000 Wh/100km which means about 1÷1.5 litres of gasoline. The effective distance of an electric car installed with lead acid batteries can be 100km with one charge for which we have to carry 300÷400 kg of batteries. A similar weight battery pack from lythium batteries can assure 350÷400 km efficient distance which can already be satisfactory.

3. ##### Output
4. For the first sight it could seem that there is no limiting factor regarding the output of an electric motor being to be installed. Concerning the choice of motors it is so indeed. The battery means the limitation again. We cannot get the stored energy as quickly as we want. The capacity of the lead acid batteries is generally given for 10 hours discharge period (0.1C). If we would like to take out the stored energy within 1 hour we could get only the 60% of the nominal capacity. As a general planning rule you have to choose the total capacity of the batteries for twice of the motor output. It means that in ideal case you have to install 8kW batteries to a 4kW electric motor. Typically the electric motors can give 2÷2.5 times of their output for a short period (1÷2 minutes) which is important when you want to speed up your car. The current consumption, too, grows of course. Choosing a much lower capacity for the batteries than the ideal case will restrict achieving this bigger current consumption. For this reason the total capacity of the batteries cannot be less than the output of the motor. That is you need at least 4kWh battery capacity to a 4kW electric motor. The lythium batteries have much better features. They can be discharged with 3C (3 times the capacity) continuously and with 10C (10 times the capacity) for a short period. So the minimal battery capacity can be lower. For example it is enough to install 10kWh battery capacity to a 30 kW electric motor (which is able to give 60÷70kW output for a short period).

5. ##### Charge
6. Using the electric car for big distances is limited first of all by the need of time for charging the batteries. You need 10 hours to charge the fully discharged lead acid batteries.
To fully charge lythium batteries 3 hours and 20 minutes is enough.
Concerning the above factors you have to decide what you want to get from your electric car both in efficient distance both in upper speed limit.
The choice spreads from the moped cars installed with 3÷4kW motor, with 50÷60 km efficient distance upto the almost without compromise "asphalt breakers" installed with 50÷60kW motor which assures 150÷200km/h upper speed limit, with 300÷400 km efficient distance.