I was just looking into this recently. There appear to be two types of cheap BMS systems, ones that just equalize when the batteries near full charge (put a small load, 40-70mv, on cells when they get over 4.1V) and the other type is typically called an "Active Balancer" it runs continuously and shuffles around charges when the cells differ by more than 10mv, many of these can move up to 1-2Amps
I think the active ones sound like a better solution, although if you have a well matched series of cells a top balancer might be adequate. Here is an example of an active balancer: https://www.aliexpress.com/item/1005002950596126.html I have no idea how reliable these are, but at that price it's cheap enough to buy and test. I also like that this particular model has a switch where you can disable the balancer action if the cell voltage drops below 3V, that way your balancer won't drain a dead battery. Note: the above model does NOT handle over charge or over discharge. That may not be an issue if your battery charger can limit it's max voltage and if your motor controller can automatically shut off when battery voltage drops below a set level. My PGP public key: https://vanderwal.us/evdl_pgp.key October 6, 2021 4:25 PM, "steve sawtelle via EV" <ev@lists.evdl.org> wrote: > I guess this may qualify as an old-school question now. > > About 12 years ago I built an electric motorcycle. I actually had it up and > running, but other > things got in the way and I am abandoning the project. The rolling chassis > will get back it's ICE > and I need to find a home for the 7" Jim Husted motor and the controls. I > have a new endeavor now - > a small cruising sailboat (CLC Pocketship). I'm thinking of using a trolling > motor as the backup to > the sails and I hope to repurpose some of my 100 A-H Thundersky batteries for > power. My batteries > have been sitting for 10 years but still are at around 3.25V. I need to cycle > them to see if they > are still viable of course. If they are, what BMS is recommended for them > now? I did a bit of > searching but didn't see much. > > -steve > _______________________________________________ > Address messages to ev@lists.evdl.org > 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 _______________________________________________ Address messages to ev@lists.evdl.org 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
