So it seems even with the much higher C-rate, NIMH batteries can't match lithium. Probably other lithium cells like a123 (which also have high C-rate, but also much higher specific energy than NIMH) are more suitable.
I think you're missing my point
I believe you're saying that for the same power, Li-ion will be lighter. True. I'm trying to say that for the same peak output current, NiMH will be lighter. So for a
low cost EV, NiMH's much higher C-rate, allows you to build a smaller, lower cost, battery pack (same peak output current) than you could using Li-ion cells. (assuming the $/Whr cost of NiMH and Li-ion are the same, which the are not Li-ion$ > NiMH$)
So here's a trade the trade off (rough estimates). Which car would you buy? :smile:
Roadster 2.5: 0-60 3.7s, 245 miles / charge, fast charge in 3.5 hrs, eMPG 100
Roadster NiMH: 0-60 ~3.3s, 125 miles/charge $5k-$10k less, fast charge in 1 hr, eMPG 50
My overall point is that if Tesla wants to succeed in the low cost EV market, they will have to invest in both Li-ion
and NiMH.
The advantage of NIMH is the 1000 cycle life vs the 500 cycle for lithium cobalt 18650, but there are lithium cells that can match or exceed that now. Advantage is you can warrant a 100 mile EV for 100k miles (100mi *1000 cycles = 100k mi), while Tesla needs to stick to around 200 miles to warrant for 100k miles (200mi * 500 cycles = 100k mi).
Yes. cycle life too.