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Battery Management - Gas Gauge Forum
Somke from DIMM board of BQ78PL114 EVM
I am using BQ78PL114 EVM. 18650 cells are in float mode 2 hours (charge current less than 50 mAmps). Than I connected load, to discharge pack ( 400 mAmps, around 5 mins). I had observed that EVM is not balancing during charge and discharge mode. So I enabled System control Register to 0x0001, to enable pumping. I had observed around 290 balance cycles on cell. Than smoke out of DIMM board.
Does anybody has experience similar issue with BQ78PL114 ? Any suggestions???
I've had no problems with our EVM board, including thousands of balancing cycles. Sorry that your board smoked!
Can you tell which component burned out? It might help determine what happened.
Is the DIMM firmly seated in its connector?
You might need a loupe or magnifier for this but can you see any solder shorts on the DIMM or bad solder joints?
D13 was burnt.
Is it possible that any configuration register cause damage to board ? (I tried to enable cell balancing first time after purchase....)
I had replaced D13 with D3. But it didn't help...
I'm not aware of any setting that can cause damage to the board as long as the battery pack is within the specs for the board. What were your cell 2 - cell 4 voltages?
D13? Hmm...the only way I can see that component burning out is if cell 2, 3 or 4 was at a very high voltage level or there was something wrong with the assembly of the board. If using D3 didn't solve the problem then Q3 (the MOSFET) might also be burned out (or even L3).
This is long shot but...how long are the leads to your battery pack? If they were very long, perhaps the extra inductance cause voltage spikes that burned out one or more components?
You are right, wire inductor may be an issue.
There was a 18 inch long 24 AWG wires connected between 18650 and EVM.
I do not know this is an enough length to cause issue...
I would shorten the wires to the minimum practical length you can manage. With the EVM adding a few more inches to your 18", that's a pretty long wire for the 300KHz balancing current to be flowing through. I have no idea if this is the cause of your problems but it definitely wouldn't hurt to shorten them.
Ours longest wire is about 5" long, the shortest is about 1".
I got new EVM. And cell balancing works fine with 18 inch wire.
But I will shorten wire as a precaution.
Great news! I'm glad the new EVM is working for you.
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