DIY lithium pack affordable? (Insight)

[payne171]

Granted, I have seen numerous posts about the cost of Lithium ion battery packs. However, I got curious about the exact cost. I admit, I am waay in over my head on making the computer work, but here is what I found:

On batteryjunction.com they have UltraFire 17670 lithium ion batteries. 3.7v, 1800maH batteries for $5.50 if you order enough of them. I figure if you wired them in units of 4 parallel for 7200maH, then run forty such units in series, you get 7.2aH at 148v, right? For $880! (PS, I may have gotten series and parallel backwards; I understand the concept and the wiring, but I get the words confused sometimes) There are higher aH batteries for sale on there that might offer better cost to benefit ratio, but that was the best I went to the trouble of calculating. If you wired this in with the factory battery pack and added the manual hybrid motor controller, you could maybe keep the assist on almost constantly.

Recharge is way out of my realm of understanding, but if you could recharge at home, this could drastically increase your IMA workload and therefore decrease engine load and stay in lean burn a lot more. Thoughts?

[jamesqf]

One thing to look at is the rate at which the batteries can accept or deliver charge. This is a common problem with ideas for replacing Gen I Insight & Civic Hybrid packs: there are fairly cheap NiMH D cells on the market, but they can't handle the required charge/discharge rates.

[Ryland]

I ran in to those discharge problems with my electric bike setup, I used 10amphour NiMH batteries tho and was only trying to draw off 8-10 amps, needless to say they did not give me an hours worth of ridding, more like 10-15 minutes, they batteries were very unhappy with the high discharge rate, lithium tends to have even more issues with high discharge, like starting on fire.

[payne171]

What order of magnitude is it too high? If you cut the discharge rate in half would that make a difference? the same website had a 100 count box of 3v Li ion batteries at 1.4aH for $115. Five boxes would net 150v at 14ah if my math is correct. That's a lot of work (and weight) but that much capacity would lighten the load on the batteries significantly. Probably not worth the weight, but a step in the right direction.

PS-Ohhhhh. 1.4aH at 100 ohms at 2v.