DIY Electric Car Forums banner

Floodie / Lithium hybrid battery experiment

40200 Views 93 Replies 16 Participants Last post by  dougingraham
I'm starting an experiment to test the effects of using lithium LiFePO4 cells in parallel with cheapo lead acid batteries.

Lithiums are 40 AH Calbs, and they'll be boosting 29HMs (formerly known as 29DC) and GC8s. My current frankenpack consists of 3 29HMs and 11 GC8s.

Phase 1 of FLHE will put 8 calbs in parallel with 2 29HMs with a JLD404 to monitor AH usage and control charging. The calbs will be charged in parallel with the floodies until approx entering gassing phase where the JLD will cut the lithium contactor while the floodies finish their cycle. 1 29HM will remain unboosted as a control.

Phase 2 will add 8 calbs in parallel with 3 GC8s and tested as above.

The experiment will try to gain info about how the current sharing works out as well as how lead cycle life can be prolonged with the aid of a lithium booster.

A successful experiment would demonstrate an increase in lead cycle life sufficient to justify the cost of the lithium booster.


See less See more
1 - 3 of 94 Posts
As long as you don't over or under charge the lithium cells you will be fine. I had a disaster with my Prius booster pack to my lead acids. Prius cells over charged. I did not have a smart charger which would be important in the case of using different batteries. Lithium charge is nearly the same as lead acid except the balancing cycle and float cycle.

You going to use a lithium charger or lead acid charger?
Parallel anything gets interesting. Paralleling different power sources is even more. But, after charging them separately , when that isolating contractor cuts back in, the fun really starts.

One will be charging the other, always, until equilibrium is met.

Series is easier. Just monitor the smallest capacity cell and charge/discharge to that.

You can parallel Lead Acid and you can Parallel Lithium but I would not mix chemistries in series or parallel.
Parallel works fine but you have to know what you are doing.

I wouldn't consider this as a solution for anything because you still have lead acid batteries in your car and you still have all of their disadvantages, namely the low energy density and high weight. The only thing people see with LA is the illusion of saving money.
Lead along side NiMH is not a good idea. Yes it can be done but introduces a high level of complex issues.

I agree that people see the illusion of saving money. It is that illusion that stops EV's from becoming main stream. I am for breaking the illusion. I will break 13,000 miles today on my Leaf. I'd say it has fully integrated itself into society just fine. Most everyone has more than one vehicle and most driving is done commuting to and from work. Like me I commute and work 5 days a week and two days off. I do go places that negate my use of the Leaf but not often. It is then that we take the gasser. We have spent so much less in fuel it is amazing. I have now gotten our TDI back on the road so the Wife will be driving that for awhile. 46 mpg is pretty good and I may try bio fuel at home now that one tank will last at least a couple months for my wife's commute.

Electric is it and Lithium is king. Cost IS less.
1 - 3 of 94 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.