Doubtful. No-load battery voltage isn’t really dependent on temperature.
I mean, you’re going to have to unscrew the enclosure to charge the battery anyway if the BMS is acting up, but giving it air won’t help.
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I’m guessing just the cold? I thought it cannot be my accessories because they are routed through the BMS discharge so it would cut them off at 3.1V - my BMS cutoff setting? Just the resting current of the BMS took it the rest of the way?
Could be the ubox. I know that motherfucker likes to kill battery packs. And no it’s not the cold.
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I’d be checking individual group voltages before charging, and charge as slow as you can.
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Wow really! I did not know that
@jack.luis is a victim of the ubox. If you aren’t riding, try measuring the idle drain. Unplug everything and monitor battery voltage
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If you can, it would be wise to disconnect ubox now if you are planning on waiting a bit to charge.
And if you don’t already have one, install a loop key so you can prevent this happening again in the future.
Out of interest, what bms?
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Disconnected the UBOX. Also have a flipsky antispark before the UBOX. My BMS is an ANT BMS. I think that’s the same as LTT?
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Nah they are different. But they seem to be a decent bms.
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I’ve been running one in my ebike for quite a while now and I like it. Kinda large, but if you can make it fit it’s a good choice.
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They have been my go-to for the few ebike batteries I have built. The build quality seems to be reasonable, although the different apps around could use some work 
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So I plug the +ve/-ve of the charger into the +ve/-ve of the battery pack (where +ve of the pack is 16S+ and -ve of the pack is 1S-) ? It feels almost like it’s illegal to do that 
but also when I think about it, is this essentially what is happening even through the BMS? Just when the BMS detect the balance start voltage, only then it balances? Meaning it’s like charging directly up until it starts balancing?
Is there anything I watch out for with the s groups while charging directly? Like do you think the 1S would charge to 4V first or they will all charge up evenly together as when one S group is higher than the other, charge will flow between them to even out? Aka they will remain relatively balanced even without the BMS. Then hopefully I can get it to 3V and charge through the BMS?
another newbie question.
when you build flex.battery for enclosure with multiple pockets, do you sit your individual 4P groups on some soft padding (foam), or do you attach it to the bottom of the enclosure (double sided tape, silicone glue,…) ?
I suppose you wouldn’t just leave it there bouncing around ?
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Mine is potted in silicone. Built by @longhairedboy . Can provide more specs later.
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I like to use 3mm eva foam on both sides
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Yup, pretty much.
More or less, yeah. The BMS can stop the charger once the first cell reaches 4.2, and drains the high one back down it’s back down below ~4.1-4.15 usually, and repeats that process until all the low cells have caught up.
God, I hope not.
Also no, that’s what the balance function of the BMS is for.
Assuming all the cells are at the same starting voltage, and assuming they all have the same capacity, they should charge pretty much evenly. If either or both of those starting conditions are true, then all bets are off. This is why it’s recommended to keep an eye on the individual p-group voltages as the charging progresses, to catch any anomalies before they turn into fires.
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“both sides”, meaning one layer at the bottom of the enclosure and 2nd layer attached to the board with the battery sandwiched between them ?
I usually line the whole enclosure with it, and put it on tge top of the battery too.
Dont stick it to the deck. You’ll hate yourself if you ever need to remove it
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Quick but vital question: I got these model 3 cells a while back from battery hookup, and like half of them have this little chunk of metal stuck to it on the lip cell:
My question is, should I strip them down and sand these nibs off? Or should I be fine with the insulation ring that comes with them + another plastic ring on top when I spot weld these?
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What the heck is that…debris from the spot welding on of the top contact by BH?
I say get rid of it. But not by sanding and creating lots of metal dust. Try a plastic spudger, or equivalent tool, and see if you can get it loose. Make sure it drops free of the cell and doesn’t wedge under the top contact.
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