It hasn't been stated clearly the Li cells have greater functional capacity for equal total capacity compared to lead acid.
You can fill the lead acids to the brim and they on't be hurt, but I understand many people never take them below 50% capacity before recharging - to get as many cycles as possible. If you park the PbSO4 for a long time you need to keep them charged up. You mostly want to use 50% SOC or less before charging. Li ion on the other hand should be stopped short of 100% SOC, say 90%. but can be safely taken down to 20% SOC. That is 70% of total charge available in a way that supports long life. You could downsize on Li for even lower total mass (and $). You don't need to be concerned about the Li cells drifting down to death without regular topping off - as long as there are no parasitic drains while not in use. This is more on the DIY side - you can manage Li ion cells well with no BMS. You need a dependable charge cut off for high and low voltages of the pack. You must never overcharge them. Lee Hart's simple Batt Bridge to monitor cell drift. Ideally you would have well matched cells and bottom balance them. It would be best to really know the type of Li chemistry and to set the cut offs accordingly. The Li cells would cost more, but would last far longer. It is even trickier whether Li cells are what you hope based on source, and supplier. On Fri, May 29, 2015 at 10:17 PM, EVDL Administrator via EV < [email protected]> wrote: > On 29 May 2015 at 16:56, Gail Lucas via EV wrote: > > > One of our local EV gurus suggested money could be saved by using some > > from Sam's Club where they can be purchased for under $90.00. > > As far as quality and longevity, it's a crapshoot. Sam's Club and similar > private-brand retail outlets buy from whatever battery manufacturer bids > lowest. You might get junk. Or you might get Trojan or US Battery brand, > but even then, it's hard to tell whether what you're getting is equal to > their regular line battery. > > You just don't know how good the ones at your local store are until you try > them, and then the next batch you get may be completely different! > > OTOH, the advantage of buying something cheap for your first EV battery is > that if you commit "battricide," you haven't lost as much. > > > Please offer opinions, but not to upgrade to lithium. That would be > > overkill for a C-Car. > > I wouldn't suggest lithium for him, but not because it's overkill for the > car - more because it might be overkill for him. > > Chinese LiFePO4 goes pretty cheap, but that's not the end of it. He'd also > need at least a BMS, and probably a new charger. (With some electronics > background, he might be able to hack up a way for the BMS to control the C- > car charger.) > > Then, to take good advantage of the reduced vehicle weight, he'd probably > want to tweak the suspension. Lower curb weight might help those marginal > brakes cope better, though. > > You know him better than I do, so you're in a better position to judge > whether he'd want to get into all that effort and expense. > > Regardless, as I said above, I think it's better to start with the cheapest > battery that can manage your transportation needs, so you don't lose too > much if you damage it. > > David Roden - Akron, Ohio, USA > EVDL Administrator > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > EVDL Information: http://www.evdl.org/help/ > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > Note: mail sent to "evpost" and "etpost" addresses will not > reach me. To send a private message, please obtain my > email address from the webpage http://www.evdl.org/help/ . > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -- To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 585-6737 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150529/0552f2b7/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
