RAV4 EV under construction
We have Certified a number of Electric Vehicles. The vehicle shown runs on an AC motor, with lithium Ion batteries. Other vehicles run on DC motors and lead Acid Batteries.
When Lead Acid batteries are used, ventilation is required to ensure that the hydrogen gas given off cannot be ignited, or fill the inside of the car. Lithium Ion batteries do not have this problem.
Weight is a major consideration, the LVVTA advise that the GVM of the vehicle cannot be exceeded, which can limit the number of batteries used, or require seating positions to be removed. A good vehicle to convert is a commercial vehicle which will have a much higher GVM for load carrying, ths will allow a greater weight of batteries to be carried.
Vacuum brakes pose a challenge- one solution is to fit an electric vacuum pump.
Power Steering is another challenge- there are electric steering systems in some vehicles, and there are electric power steering pumps also.
Good news is that Electric Vehicles are exempted from Road User charges, which makes a huge saving in runing costs, (along with the saving in fuel of course)
To ensure that you avoid any LVV Certification problems, talk to John at an early stage
This is a very interesting website- Earthlings Electric Vehicles
John Brett Technology Ltd. 0800 LOW VOLUME (0800 569865)
I am converting a 1995 BMW (328i) to be electric. Its GVW (Gross Vehicle Weight) from the handbook (and the plaque attached in the engine bay) is 1780 kgs.
How much I can increase the weight? I have removed around 307 kgs (engine, exhaust, radiator, petrol tank etc), but would like to use 12 batteries that weigh 37kg each (444kg total), along with a 73 kg motor and around 20-30 kg of other equipment. So there is s net gain of ~235 kg.
The car has 2 front seats, and the rear seat is 1250mm, which I believe means it’s a 5-seater.
If I fix the center rear armrest in the lowered position to reduce the number of seats to 4, I believe I save 80 kgs as far as the LTSA is concerned
This would make the total weight (1780-307-80+444+73+30) = 1940 kg.
Is this an acceptable increase over the GVW (about 9%)?
Hi Andrew-
Your figures:
Car manufacturers do not normally publish Gross Vehicle Mass for passenger cars.
Since your car has that information, this is what we would use.
The usual procedure we use to design Electric Vehicles is:
1 Determine kerb weight, in unmodified state.
2 Add the fuel load, passenger loads to give a calculated GVM (note that Landata often shows GVM for cars, if so, then that figure is the starting point)
3 Subtract passenger weights and fuel weights to give maximum allowable Kerb Weight for MODIFIED vehicle.
If you estimate the weight of the original engine and fuel tank being removed, this is the maximum weight your new motor, control system and batteries can weigh (which is what you have done).
Passenger cars do not have much margin, light commercials are MUCH better and they always have published GVM figures.
One possibility is to remove the rear seat altogether, to give you ( 3 x 80 =240kg) extra battery capacity.
If you reduce the seating positions to 4, you need to fit some PERMANENT armrest or such to stop that seat being used. We have had this issue on Limousines, and LVVTA are quite inflexible about this. I have had Certifications turned down because an armrest fixed down was not deemed permanent enough!
Re the suspension- if you increase the mass you MAY need to up-rate the springs to keep the suspension operating correctly. There is no mandatory ride height, the LVVTA Standard is performance based- i.e. the suspension still has to work properly.
Hope this helps
Regards
John
You post great articles. Bookmarked !
Hi there can I reference some of the material here in this post if I link back to you?
GVM Increase- I am advised by LVVTA that the GVM may NOT be increased over the standard rating. Check what it is on LANDATA (either through Motochek, Car Jam or have a WOF agent look it up directly on Landata.You will be surprised to see that there is usually no allowance for luggage- for example a five seater car will have allowance for 5 passengers at 80 kg, but NO luggage, NO towbar downforce!
Feel free- let me know the link