I have a 24 v LiIPO4 bank with an overkill BMS. My number 2 cell keeps getting over voltage protection. Right near end of charge but when it cuts out it kicks my Victron Multiplus II inverter off. How to you discharge a single cell. I tried finding 3 V bulbs on amazon. What do you guys use.
Over Cell Voltage
- Thread starter ddutton
- Start date
sunshine_eggo
Happy Breffast!
12V bulbs, resistors, etc.
I'm assuming you also have an MPPT or other charger in place. What is likely happening is that the charge cut-off for protection is causing the charger to spike the voltage > 33V, which pisses the MP II off.
Recommend you:
reduce absorption to 27.6V
set fixed absorption time of 2 hours
set float to 27.5V.
Ensure BMS is configured to begin balancing at 3.40V with 20mV cell difference and ensure that it will also balance when NOT being charged.
The above configuration should reduce/eliminate the over-voltage protection events and give the BMS more time to passively balance the cells.
Check the connections to that cell. Half the cell voltage issues on the forum can be attributed to poor connections. Disconnect the wires, verify that the terminals on the wire are firmly attached, clean the cell terminal and bus bar surfaces and apply a small amount of anticorrosion/conductive paste such as Noalox, No-Ox-ID or MG Chemical 847.
Adding to what sunshine_eggo posted, lower the charge amps. That will give the battery more time to balance.
Adding to what sunshine_eggo posted, lower the charge amps. That will give the battery more time to balance.
Agreed check connections first.
I used this 6 volt car head light and wired some alligator clips to it.
It worked well to pull down runner cell(s) when charging in the upper knee.
In the long run ended up with active balancers on the 2 8s Lifepo4 battery banks with Overkill Solar BMS. Have not had a problem since.
Shop around... Can probably find a better price.
This one looks the same.
Andy at Off-Grid Garage did an interesting video on the subject using a circuit board to turn on/off a Heltec active balancer. My system uses the Heltec active balancer (turn it on/off with Victron BMV-712 battery monitor) in the upper knee and works well.
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