My personal experience is with the LiFePOcells, but the issue is there for all/most? It's a shame because they are the most affordable (well maybe, I haven't bought any since 2015).
In particular, the temperature at which trouble starts is significantly lower for LiFePO. I think if you go right out and use a full charge you have no large issues. It's probably best never to float them like people do with PbSO cells. When fully charged any excess charging just heats the cells up. I had a pack for my trike, about %500 worth. I would ride to work ~25 miles in a little more than an hour. That was about all it was good for with new cells. I could average about 23mph. I would park it at an outlet on the south wall of a building and set up the charge. Not a very sophisticated charger. It would charge fully and I would let it sit and soak. After a couple months of this I really started having low capacity. Not a very economical situation. I became aware of the work at the Jeff Dahn lab at Dalhousie and got a much better understanding what I was doing wrong. Too late though for that pack. I think stopping short of 100%SOC is a good idea even if you are going to ride off immediately. In terms of how to measure and manage the charging, the voltage changes very little as SOC rises. How to get it right? Its a conundrum. Jack Ricard put some effort into watching cells sit on the shelf and they do slowly lose SOC. He knew how to measure SOC accurately by drawing them down. He also saw a small but significant and permanent loss from full capacity, year after year, just sitting them in storage. I am not clear on what exactly causes that loss. LiFePO could charge back up pretty good if you didn't do what I did. On Sat, Jul 24, 2021 at 11:40 PM EVDL Administrator via EV < [email protected]> wrote: > On 24 Jul 2021 at 21:04, Michael Ross via EV wrote: > > > The worst thing you can do to LiFPO is to charge it fully, and let it sit > > around, especially in a hot location. > > Isn't that the case for lithium batteries of any chemistry? I'm not a > lithium expert by any means; I'm just asking. > > It occurs to me that some of Chris's parasitic loads could be coming from > "inside the house," so to speak. That is, they might be from the BMS. > > I have 24v and 36v 10ah LiFePO4 batteries with a BMS with logic that's > powered by a 12v tap (not the optimum design), and the 4 cells that power > the BMS always take longer than the others to reach full charge. For long > term storage I have read a suggestion to disconnect the BMS if possible - > but don't forget to reconnect it when taking the battery out of storage. > > David Roden, EVDL moderator & general lackey > > To reach me, don't reply to this message; I won't get it. Use my > offlist address here : http://evdl.org/help/index.html#supt > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > First they came for the journalists. We don't know what > happened after that. > > -- Unknown > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > _______________________________________________ > Address messages to [email protected] > No other addresses in TO and CC fields > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/ > LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > -- Michael E. Ross (919) 585-6737 Land (919) 901-2805 Cell and Text (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Tablet, Google Phone and Text -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20210725/0f0b3fde/attachment.html> _______________________________________________ Address messages to [email protected] No other addresses in TO and CC fields UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/ LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
