Interestingly, this weekend I just spent a few hours with one of the guys at LionEV, the Lithium battery manufacturer (http://www.lionev.com/) our electric car club has been working with. He likes to store and ship his lithium cells at 40% of their rated charge. However, he can and does ship them at 100% charge, though the shippers don't like it and usually charge extra. He actually had one shipping company try to charge him more because they believed the cells would weigh more fully charged?! I rode in their plug-in hybrid Ford Escape and it was very nice. I also got to help
trouble shoot a battery pack installation problem in the electric Ford Ranger pickup. That was fun.
We also talked about a lithium pack for my E10m (once I get it restored). List price would be $2400 for a 100AH pack if I remember right. He said I would get 2000+ cycles before the pack would be at 80%, and another 3000 cycles before it would get to 75% of rated capacity. That would be more than a lifetime pack for the tractor I would think. He also said he thought our local distributer here in Dallas could get me better volume pricing, since I'd be using 108 cells to get a 36v pack. I doubt that would ever be worth it to me, though if you ran a mowing service it might be worth the extra expense because of battery life. The stock Elec-trak charger would not be good enough for a lithium pack.
As far as NiCds go, I ran them with R/C model airplanes years ago and if I remember right it was bad to let them sit at a
discharged state as they could reverse polarity. I would think the best approach with NiCds would be to cycle them monthly, ie dishcarge them fully and then fully recharge them. I did this occasionally even while they were getting good use to try and keep them from memory problems. It's been a long time since I used NiCds though. I'd buy lithiums over NiCds now every time.
George
I know very little about lithium. NiCd can be stored in any state of
charge, but the preferred storage method for CELLS long term is discharged
and shorted. From what I've read, a NiCd BATTERY should not be fully
discharged for storage, as it can result in reversing a cell.
David Roden - Akron, Ohio, USA
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