Battery issue need advice

acesx

10 µW
Joined
Jan 7, 2015
Messages
5
Location
Long Beach CA.
Hi there,
I have a battery issue ,
When plugged into my bike it reads dead ,
When I test with a meter it shows 54v
When I attach the charger it shows green and won't charge it .
Little LED lights on the battery show dead , but green when the charger is connected.
.I am stumped

Any advice is welcome .. please
 
BMS has shutdown both the input and the output to prevent damage (fire/etc) to the cells. The voltmeter reading is a "ghost" voltage caused by tiny current leakages thru the FETs; if you put a load on it (even something very small) the voltage will rapidly drop or disappear.

Most common reason is a broken or disconnected sense (balance) wire from a cell to the BMS.

Second most common reason for that is a cell (group) that dropped below the safe recharge voltage during a ride.

Third most common is blown FETs in the BMS, but that usually only happens on the discharge side, and the pack still charges fine, so is probably not the problem you have here.

Some packs actually include a useful fuse between the battery positive and both charge and discharge ports, so that could blow, and cause most of what you see, but you wouldn't normally see the ghost voltage for this case, so it's probably not the problem.

You'll have to open the pack up, and check each of the things--I'd start by checking voltages on the BMS's balance connector at the actual BMS board solder pads.

Set voltmeter on 20VDC. Put black meter lead on battery negative. Red meter lead on first balance wire solderpad on BMS board. Write down the voltage you get there.

Move black meter lead where red one is. Move red one "up" to the next balance wire solder pad. Write down the voltage. Repeat those steps until you get to the main battery positive wire with the red lead; you'll have 13 voltages for a 48v pack, and 14 of them for a 52v pack.

Post all the voltages here when you're done, along with all information you can provide about the pack's usage history and any problems it's ever had (especially recently), and any problems youv'e had with the bike itself.
 
acesx said:
Hi there,
I have a battery issue ,
When plugged into my bike it reads dead ,
When I test with a meter it shows 54v
When I attach the charger it shows green and won't charge it .
Little LED lights on the battery show dead , but green when the charger is connected.
.I am stumped

Any advice is welcome .. please


What happened between when it was working and when it stopped? (did it shutdown when riding/accelerating, randomly, etc.?)
 
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