Homebuilt electric car Battery conundrum.

[conaman551]

Hi all.

I planning to build an electric car at home. I have no expierence with electric vehicles but I studied physics at high school and know a fair amount about cars. After seeing homebuilt electric cars on you tube and elswhere I've been inspired to try bulid one also. I am going to try convert an old sedan or hatchback to electric power while still using the existing transmission.

The motor will be getting is a DC, 96v, 21Kw forklift motor. So far Iv'e established that if i use a battery pack supplying 300Ah @ 96v this should allow for about 1-2 hours drive at highway speed or approx 150Km range.

I definitely want to use Li-ion cells and I established that It would be cheapest for me to buy 2600 3Ah 3.7v cells @ $1.50 each on ebay. By having 100 battery packs in parallel each containing 26 3.7v cells in series, this gives me the 300Ah 96v battery i need.

After some quick math Iv'e also established that when the motor is at full power (21Kw) each cell is putting out 2.2A or 8.1 Watts. Is this current too high for the 18650 cells? I've heard that at low current <1 amp a cell is more efficient and is more likely to supply the rated capacity of the cell.

 

[benny61]

I definitely want to use Li-ion cells and I established that It would be cheapest for me to buy 2600 3Ah 3.7v cells @ $1.50 each on ebay. By having 100 battery packs in parallel each containing 26 3.7v cells in series, this gives me the 300Ah 96v battery i need.

I've seen some really poor cells on ebay. They're mass produced from China and break easily. I'd advise to steer clear.

I think you should build a prototype model and scale up from that.