Red LED on BMS

Blunderbuss

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Mar 11, 2018
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I have just connected up the BMS on my first battery build and three of the LEDs are lit up. I can't find anything to tell me what that means, does anyone know?
 

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Nealh

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Aug 7, 2014
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They are I believe cell group charging indicators.
 

Blunderbuss

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Mar 11, 2018
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I haven't yet connected up the charger or the output, but the cells were fully charged before i assembled them - could it be the BMS reading an imbalance (or overcharge) of those cell groups, and then doing a balancing of them.

Only the cell group 4 LED is on now.
 

soundwave

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May 23, 2015
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I haven't yet connected up the charger or the output, but the cells were fully charged before i assembled them - could it be the BMS reading an imbalance (or overcharge) of those cell groups, and then doing a balancing of them.

Only the cell group 4 LED is on now.
if you have charged each cell to 4.2v then put the batt together then thats a bad idea as 1 short connecting the bms the hole lot could go bang.

imo the bms is balancing the cells and when all of will be fully charged on all the cell groups.
 

Blunderbuss

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Mar 11, 2018
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The voltage is 54.4 so hopefully it is balancing.

I have learn't a lot doing this first build :) i will see what it is doing in the morning, but may put it in a sheltered spot outside for the night!
 
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Blunderbuss

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I have checked this morning and all the LEDs are off :), but the voltage now reads 58.3!!!!!!

I can check individual cells and they are at 4.48, so the maths works out (13 x 4.48) but how have i gained 4 volts across the whole battery?

This weekend i shall get the XT60's on it and connect it up to my bike to see what happens, both for running the bike and charging back up.
 

wheeliepete

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Lets hope your meter is wrong:eek:otherwise you have a bunch of badly damaged cells. Not sure I would want it in my house. What cells have you used? What's the voltage reading on your charger?
 

Blunderbuss

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Mar 11, 2018
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The cells are an LG 2200MaH

I have just checked again and the voltage is now 60.9V :eek: - so i am expecting fireworks soon, but i cant detect any heat.
 

peter.c

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Apr 24, 2018
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Have not been brave enough to build a pack yet:confused: can you test the volts on each string If you get higher volts of one or is it the the bms
 

Blunderbuss

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Mar 11, 2018
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Cambridge
Yes, you can use the soldered connections from the battery to the BMS to check the voltage between any of the packs - and they all read to within 0.02V of each other. I was thinking he same thing, hoping one of the group of cells would be way over!

It is possible that the BMS is faulty, i have one of an old battery (the same 13s) so i can give that a try.
 

wheeliepete

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Sorry if I sounded alarmist, but PLEASE put that pack somewhere out of harms way. I would not attempt to try disconnecting anything. If it doesn't fire bomb in the next 24 hours, then maybe take a look again.