Charles! I have a question. Can’t think of anyone better suited for. Lacroix Jaws 2.0 version. After I switched out the stock belt drive for the BN M1-AT Gear Drive and replacing the stock 6389 190kv’s for 63100 190 kv’s the board would not charge. Charger showed green as if fully charged but was no charge left.
After downloading the xiaoxiangBMS app it started to charge properly again!
But now It will not charge again. The battery shows fully charged in xiao & stormcore app and shows green light on charger again but it is not fully charged.
I answered on reddit, but I’ll copy the answer here too.
To recap: The board charges completely normally until the battery is right near full charge, then the BMS voltage readings start becoming sporadic. This is then triggering over voltage faults and shutting charging off even tho the charger is connected. That is why you see the normal balancing screenshot and then the next screenshot, in the same minute, with two cells showing massively over voltage.
Obviously that voltage jump is impossible to have actually happened, so it is clearly an issue with the BMS accurately reading the voltages of the cells.
To be frank I don’t know for sure how to fix this as I’ve never implemented a fix for it before, however I can tell you from my vast experience with this BMS that this is a Lacroix application specific problem. That leads me to the belief that the lacroix sentinel is the root of this issue as no other board has that device in it.
I know for a fact the BMS needs a strong ground to the pack negative or you will get funky readings at all voltages. I have no idea how/why the sentinel would cause this specific kind of issue, but my theory on how to fix this issues is to add a wire from the battery pack negative to the BMS directly (B-) bypassing the flow through the sentinel as it’s wired from lacroix.
Hope that helps, and if you do try and implement this please, let everyone know how it went.
I sincerely appreciate the detailed reply. I’m hoping to find an easier fix as physically rewiring or adding wiring is rather intimidating for me as I am not the most technically experienced guy. (my first board). Are there are any other possible options?
Xiao app seems to show full charge but its really only at about 65%. If I drained more of the battery before trying to recharge would that help? Thanks!
I strongly believe this is a hardware problem and I’m not aware of any other possible options, so I will differ to others if anyone else can offer a suggestion.
Draining the battery more or less will not make a difference in my experience. The % number in the app is unreliable in my experince.
There are other 3rd party apps on both app stores that will read the BMS data you can try, but I don’t think you will have differing results. (Make sure you fully shut down the other apps when trying new ones of the BMS will not appear)
Always go by the voltage of the cells. They should be close to 4.2v each at full charge. Total battery 50.4v. They’ll never really reach 4.2 in my experience, after charging, good condition cells typically settle at around 4.18v
Your pictures show the majority of your cells at around 4.16, this is basically full.
I’d be concerned about cell 12 being a bit low. You can turn on the always on balancing feature to bring this in line with the other cell values and then switch back to charge only balancing.
The fact that cell 5 reads high with the charger attached is definitely concerning. I’d be closely monitoring the pack over the next few charge cycles to see what is up.
Edit: just noted that 12 only reads low when 5 is reading high… i agree with @A13XR3 that it’s likely a hardware issue. Ignore the bit about turning on always balance
Thanks so much for all the responses! Before reading these replies I tried draining my battery a bit more down to about 53% then tried charging it up again from there.
For some reason it seems to be working fine now. I’m not entirely sure about the numbers but the charger would turn on and charge this time and I did not get any codes/alarms this time.
I was going to try to turn off both balancing options if it would not charge but didn’t have to. Not sure if it did it on its own as it just started charging and I had no issues during.
Now I’m even more confused than when I started this thread smh. I should have clicked on the bms read, under bms settings, but I didn’t want to chance fucking up anything during the charge, I was on pins and needles during the whole charge waiting for the board to blowup! But tmrw after I drain the battery back down to 50% again, I can try to re-charge up again and this time I will read bms and post the numbers.
Here are the numbers screenshot from the main initial page in case y’all can tell any inconsistencies from it.
Ok I grew some balls and clicked the bms read AFTER it was full charged and I had turned off charging and unplugged so will post screenshots of that too, including stormcore app screenshots after charging complete.
Hey Hey! Any idea where I can buy a replacement stormcore switch on/off button? Mines been acting up on and off since I’ve had it but since upgrading motors and messing w/ vesc tool/ xiaoxianbms app its acting up more often. Or if any ideas on an aftermarket solution pointing the the right direction greatly appreciated! Thank so much!
I was having issues with my button and figured out it was a broken solder joint at one of the wires that was causing the issue. It was in the shrink tubing so it was not obvious. You might want to check your wires.
I’m getting a weird issue with my Stormcore 60d+. After I got magic smoke come out of one of my motors, the on my phone can’t find the Bluetooth signal from the Stormcore but my laptop can. Anyone have any idea why this is happening?
@jpaulglobal this is not ok. something is seriously wrong with your BMS. You should NEVER have any cells above 4.250v (trigger value for “Cell over voltage”).
Having P groups at 4.373v and 4.383v indicates something is seriously wrong. That is way too much energy to have in the cells, and it is dangerous.
I would recommend getting your pack checked out by an experienced battery builder.
Thank you for this lead. When you say “shrink tubing” can you help point out what that is specifically? The only shrink tubing I can think of is the blue, yellow and black motor wires…
I have had the solder joints come off on me as well. I believe he is referring to the back of the rgb button. There are multiple wires that go into the backside of the button, and there’s is heat shrink covering the connectors where the wires are soldered into. That is where the joints can break.
Watch the cells as it is charging, making sure they don’t go beyond 4.25v as @Shadowfax said. If they do, unplug the charger. Something is wrong and needs repaired. Like he said, that could be very dangerous.
Wonderful replies, Thanks Noah. Appreciate the break down on the solder joints and I’ll keep an eye on the cells while charging next! Looks like I may need to inspect and solder as I can’t seem to find a new on/off button to buy as lacroixs out of bizz. Is there an aftermarket switch You might recommend as a work around before trying the soldering myself? Preesh!
I dunno if that’s such a good idea that they’re kinked from the factory, the ones on mine are bent pretty badly but the button works.
The whoole shebang is caked in black hot glue so they are sort of protected but still.
