Tried making a BMS charger with an LLT Smart BMS, with the following wire diagram, but I got a whining noise and smoke from the BMS. Plugged it first to charger, then battery leads, then balance wires, where it started smoking. Looks like some discoloration on two of what looks like resistors. What went wrong, and how screwed am I?
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Why did you plug it into the charger before plugging in the balance leads?
Are you 100% certain your balance leads were all in the right order?
Itâs an external BMS, so I have to plug in the battery and balance leads at the same time, so order of operations should be Charger > Battery > Balance.
Pretty sure, the only place where it might have gone wrong is if the two 6Ses got flipped, but Iâm not sure on that part. Continuity looked fine, with no shorts anywhere.
Hm. Well I definitely think that the order of operations should be as it would be when attaching to a traditional battery
So, battery, balance leads, and then charger.
Plugging in the charger first seems like a bad idea
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Also, normally if they were out of order, one of the balance transistors would have blown but it looks like you blew something else
Whoops yeah youâre right about that, forgot about the inrush. Still, that shouldnât kill the BMS right? It seemed fine until I connected the balance wires.
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Unsure - I wouldnât try it though so couldnât tell ya haha
I would check your balance wire order again. Remember, it should always count up in succession, according to BMS documentation. Typically it counts up from the negative, ending with the final S group as the positive lead
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K Iâll double check again. Do you think the BMS is dead? Havenât attempted to plug it back in yet.
Could be, it looks like that one resistor is burned, but hard to say
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how you connected the leads
it happened to me too because i followed a wrong wiring diagram on the llt homepage
first (black) to bat- then next (white) to the first positive then all following leads to positive till you reach the last (red) one which goes to bat+
In my wiring diagram i uses the first (white) lead was missing so i attached i to the 2nd positive which delivered too much V to the bms => noise and smoky
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Yep theyâre 2 6S packs. Huh I had this diagram checked here before I started, guess it got missed.
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If I were you Iâd use 2 6s BMS, much safer anyway.
I canât get my METR to pair to an LTT, suggestions?
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Throw some fish paper over those balance leads before you shrink that wrap
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How would that work with a single 12S charger? The whole reason I went this route is because charging single batteries took too long (~24 hours). This way, I can cut down charging down to just under 2 hours.
Use the BMS only for balancing and bypass charging. Thats how I have it for my 6s lipos, two small balance boards and the rest handles the charger. You obv. need to have voltage cutoffs handled otherwise, by the Vesc and the charger.
Sometimes I forget to close the LLT app and the Metr canât connect since the XiaoxiangBMS app is still paired to the BMS.
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