IMHO, at a MINIMUM you should at least monitor half pack voltage vs the other half (without causing an imbalance in the process) and terminate charge or take action accordingly. Maybe I should quit talking about it and make a kit.
Fix or workaround for BMS issue
I have been working on installing an aftermarket kit on a Prius to makes it into a plug gable hybrid. I have as input a 16s LiFEPO4 battery.
I have a problem however with the BMS that come with the kit. Cells #12/16 and cell #13/16 both read incorrect voltage (cell 13 reads .2V too high compared to the multi meter reading and cell 12 reads .2V too low). I am worried that the BMS will then "burn" these 2 cells by overcharging cell 12 and over-discharge cell 13.
I was wondering if there is any way I could re-adjust the BMS reading so it properly detect the correct voltage. Otherwise, would it be possible to maybe insert a low resistance on one or many balancing cable to compensate for this reading ?
I could also just buy a cheap BMS circuit without monitor but then I have no idea how I could trust such circuit without feedback.
The kit in question is an Enginer kit (bought a used one)
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I have a problem however with the BMS that come with the kit. Cells #12/16 and cell #13/16 both read incorrect voltage (cell 13 reads .2V too high compared to the multi meter reading and cell 12 reads .2V too low). I am worried that the BMS will then "burn" these 2 cells by overcharging cell 12 and over-discharge cell 13.
I was wondering if there is any way I could re-adjust the BMS reading so it properly detect the correct voltage. Otherwise, would it be possible to maybe insert a low resistance on one or many balancing cable to compensate for this reading ?
I could also just buy a cheap BMS circuit without monitor but then I have no idea how I could trust such circuit without feedback.
The kit in question is an Enginer kit (bought a used one)
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re: batt-bridge, I went with individual (cheap) voltmeters because the batt-bridge needs a few volts imbalance before it triggers, and knowing the voltage of each pack half to 0.1 volts or so is more useful info.
re: diode drop, it works, only caveat I can think of is if your charger has a "trickle charge" or otherwise tries to top-off the pack repeatedly. If left plugged in it may overcharge since at very low currents there is almost no voltage drop in the diode.
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re: diode drop, it works, only caveat I can think of is if your charger has a "trickle charge" or otherwise tries to top-off the pack repeatedly. If left plugged in it may overcharge since at very low currents there is almost no voltage drop in the diode.
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