I used one like this for $40: https://www.ebay.com/itm/403078590721 (Ships from California)
Hook it up so the key, charger and all other accessory circuits run through the BMS, but the high-current motor controller goes direct to the pack. Do not "tap" the middle of the pack for 12v, use a DC-DC hooked to the key circuit. This will protect the cells, but the balance current is very low, so if they ever get too far out of balance, you may need manual intervention, but I've found if you use quality LFP cells, they stay in balance easily. So the BMS will open the circuit from B- (battery minus) to P- (in/output), so the only things that would be connected to the negative of the pack are the BMS B- terminal and the high-current feed to the motor controller. Everything else that used to connect to the negative is instead connected to P-. This will open the loads when the pack gets too low, and will open the charger circuit once the pack is fully charged. It only supports up to 60A, so this is why we hook the motor controller direct. You just have to make sure that the enable line (key switch) for the motor controller goes through the P- connection so the BMS can properly disable the cart when the battery gets too low. On Sun, Apr 9, 2023 at 10:54 AM Greg Williams <mr.g...@gmail.com> wrote: > Phil,. Sources for BMS? Seems way expensive for these things. > > Greg > ------------------------------ > *From:* (-Phil-) <p...@ingineerix.com> > *Sent:* Sunday, April 9, 2023 10:50:16 AM > *To:* Electric Vehicle Discussion List <ev@lists.evdl.org> > *Cc:* mr.g...@gmail.com <mr.g...@gmail.com> > *Subject:* Re: [EVDL] 144 volt Sepex motor available > > I recommend Large-Format LFP cells. They are more forgiving and safe, and > you can usually keep your existing charger. 12 cells in series is a > perfect fit for a 36v cart. Wire up a low-cost BMS so that it disconnects > the key signal. Last one I did, I used the Calb CA180 cells (180Ah). > > On Sun, Apr 9, 2023 at 10:32 AM Greg William via EV <ev@lists.evdl.org> > wrote: > > Leaf cells for my 36 v golf cart > > Will these work out well in a EzGo golf cart? Ideas for a BMS? > > Good sources near Seattle? > > On Sun, Apr 9, 2023 at 8:41 AM Steve Gaarder via EV <ev@lists.evdl.org> > wrote: > > > I have a motor pulled out of an old SCT Rabbit. It's rated, I believe, > at > > 144 volts, 17 kW continuous, 33 kW peak. As far as I know it's in working > > condition. Pay me more than the scrap value and it's yours. It's > located > > in Ithaca, NY. > > > > I also still have those BB600 NiCad batteries, btw. > > > > Both need to be gone by the end of the month. > > > > thanks, > > > > Steve Gaarder > > _______________________________________________ > > Address messages to ev@lists.evdl.org > > No other addresses in TO and CC fields > > HELP: http://www.evdl.org/help/ > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230409/971d1c9f/attachment.htm > > > _______________________________________________ > Address messages to ev@lists.evdl.org > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20230409/0f7100ae/attachment.htm> _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields HELP: http://www.evdl.org/help/
