No! However, if you want them all at the same exact voltage then connect them in parallel for a day. Then connect them in series and charge the pack.
Sent from AT&T Yahoo Mail for iPhone On Saturday, March 13, 2021, 2:19 PM, Willie via EV <[email protected]> wrote: On 3/13/21 1:57 PM, Lee Hart via EV wrote: > John Titman via EV wrote: >> Hello: Nobody answered my question The whole reason I need to balance my >> batteries is that a number of batteries reach 3.6 volts before the >> others, >> who only reach only about 3.3 volts The Orion BMS shuts of the >> charger and >> balances the batteries but, the same problem occurs after the next >> recharge . I've discharged the batteries a number of times but, they >> still >> bounce back to about 2.51-2.53 volts . Do they need to ALL be exactly 2.5 >> volts before recharging? > > Hi John, > > When the batteries reach anything close to 2.5v, they are effectively > dead -- no useful capacity remains. It doesn't matter whether they're at > 2.5v or 2.6v -- they're still DEAD! > > I don't recall what current the Orion uses to balance, but I think it is > pretty small (milliamps). It may be that your batteries have aged to the > point where the differences between them are too large to balance with a > small current. I see several possibilities here: The pack may have some bad cells as you speculate. It may be that the pack has never been properly balanced and the BMS is stopping charging when a cell or two reaches max voltage and John has not recognized that some cells have never been brought up to near charged voltage. As Lee mentions, the first thing to do is examine the voltage on each cell immediately after the BMS has turned off the charger. Also, see if total pack voltage is reasonable. Should the pack need initial balancing (top, not bottom) and does not have bad cells, several options: 1) fool proof is putting all cells in parallel and charge to ~3.4v (assuming LFP cells) with a single cell charger (could take weeks with a typical ~5 amp charger) 2) repeatedly run pack charger and allow the BMS to slowly bring up the low cells (could take many hours). Each BMS/charger cycle improves balance only slightly. 3) Identify low cells and charge them with a single cell charger to about 3.4v (could take hours per cell with a ~5 amp charger). If you have several single cell chargers, you can do several cells at a time. John has given us insufficient information. Does the car have an EVAlbum page? _______________________________________________ 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20210314/ae3d28b0/attachment.html> _______________________________________________ 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
