val4o said:
Screenshot_2023-02-05-15-43-53-72_425154530a3df2b6520d5742e232d9aa.jpgScreenshot_2023-02-05-15-43-58-99_425154530a3df2b6520d5742e232d9aa.jpg
Battery was charging fine, It's brand new, barely 10miles on the bike. Cells were all within 0.1v apart.
Not according to your first screenshot--it says they are 0.614V difference from highest (3.125v) to lowest (2.511v). I don't see any screenshots of the actual cell group readouts, so I couldn't tell you what you've got at the moment, but that's what it was at the time the info displayed on that screenshot was logged (it does not say when).
But even if they were only 0.1v apart, that's a huge difference, indicating unmatched cells (which will only grow worse with time and usage). If the pack was built right of good well-matched cells, there would be a tenth of that difference, if any.
Unfortunately "brand new" doesn't mean anything regarding cell balance, condition, etc., because it's too common for packs to be built of completely unmatched cells that will never stay in balance, and that is probably what you have there. At best the pack builders may test them to be below some level of cell resistance, and above some level of capacity--neither of those does anything to match cells. They may also sort them by voltage (which means nothing regarding cell matching, that's just a safe pack building practice).
Some manufacturers (probably not yours) even use recycled garbage cells to build packs from....
I haven't used it for about t month when the temperatures dropped below 0° for a while, battery was at 74v before that. So it dropped that much just from sitting in the cold?
Probably not. It probably has either bad cells that have self-discahrged and drained the groups they are in, or the BMS itself drained the groups (or the whole pack), or more likely there was something on the bike (controller, display, etc) still connected to the pack and draining it while you weren't using it. Or some combination of these.
And if i change the low voltage parameters to 2.5v it should start charging then?
You'd want to check the cell-manufacturer datasheet (if available) for your specific cells to be sure that's a safe voltage to recharge from first.
Assuming the cells don't have any damage and that's a safe voltage to recover from, you'd need to change any parameters that the pack or cells are not within the limits of, including the difference between cells, so that the pack/cells are then within those limits. Be sure to note down anything you change so you can put it back.
And remember--the limits they put in there are generally there for safety--when the BMS disallows charging or discharging, it is trying to prevent cell damage that can lead to a fire.
There's one more error in warning info, "UnitTotalRelatedProtect" any idea what that's for?
No, you'd have to see if it's in the BMS or app manual or help, or if anyone has posted that specific term here on ES for that brand of BMS / app.