Tuesday, April 21, 2009

Batteries Ordered

I've ordered my batteries!

After going back and forth between Lithium and Lead countless times, I've finally decided on Lithium! LiFePO4 to be exact. These are a relatively new battery chemistry that don't have the energy density of other Lithium Ion batteries, but they are significantly cheaper and much safer.

Thundersky TS-LFP100AHA

They'll last 2000-3000 cycles depending on amount of discharge. I've ordered 30 cells, 3.2 nominal @ 100AHr, for a 96V nominal total voltage. Minimum voltage for a cell is 2.6V, which corresponds well with my controller's 80V minimum. Maximum voltage for a cell is 4.2V, which at 126V peak won't overload my motor. The batteries should fit in a single grouping underneath the hood, and the final weight/balance of the car will match very closely to stock. I purchased with a group from diyelectriccar.com - batteries should arrive in 2-3 months.


Duncan G said...

Can you tell us how much they were?
Thanks - and great blog btw

Clint said...

The group purchase was $1.10/AHr so $3300 for the batteries + $700 customs/shipping. I almost ordered from Sky Energy off Alibaba.com - they quoted me just $1.15/AHr for my relatively small order.

Alan said...

Any update on the batteries?

I just got my college 78 Spitfire back from my sister (moved in to a house with a garage) and was in the process of trying to get it running well again. This looks much more enticing to me than doing yet another round of fights with the finicky distributor and Zenith-Stromberg carb.

It's been a while since you started, so now that you've settled on batteries do you have another performance estimate given the final weight and such?

Clint said...

Batteries still haven't arrived yet, maybe another month? The Spitfire has been a fantastically easy car to convert. I highly recommend it!

According to the EV calculator (http://www.evconvert.com/tools/evcalc/), my estimated performance is:
25 miles @ 30 mph
19 miles @ 40 mph
14 miles @ 50 mph
Est. final weight: 1950 lbs (nearly stock!)

Those ranges will take care of 95% of my driving. I'm going to be moving at the end of the year; so if need be, I'll pick up a second 96V 100Ah Lithium pack to double my range later on.

Alan said...

You have quite an understanding wife to let you drop another $3k on batteries for your project car after spending $4k on the first set.

Thanks for posting the performance numbers. If I built it I'd want to be able to drive it to work to show it off, but I work 40 miles from work each way and don't know how I'd recharge it at work. Would need 80 miles range at around 40 mph. Doesn't look too doable.

Clint said...

80 miles at 40 mph is very doable with Lithium but obviously at a higher price. I'm basing my performance off the evcalculator; I've heard several people say it's too conservative and you'll actually get better with real world driving. I won't know for sure until it's done.

My wife is definitely understanding. She has her own little activities too though (horseback riding and dog agility). Spreading the costs of the conversion out over a year has helped as well.