question

Jon S avatar image

Victron LiFePO4 cell voltage not balancing

Hi,


I have 6 batteries in a bank comprised of Victron 300amp LiFePO4 batteries. Two of the batteries have voltage balance issues. The problem shows up 2 ways:

1 - When charging reaches Absorption one cell is behind the others. The battery is at 14.2v but the cells are at 3.62, 3.62, 3.61, and 3.35. I have this same condition on another better. One is Cell 1 the other is Cell 4.

2 - When charging reaches 98% (per the CCGX display) the troubled cell is running very fast to 3.74v while the other cells are at 3.40, 3.37, and 3.37. The BMS does its job and stops charging. The voltage drops down to 3.6 then the charger kicks back on and the cell quickly rises to 3.74 and charging cuts out again. This repeats until the battery reaches 14.2 and goes into absorption.


I have the following components and firmware:

* Lynx Shunt 1000A VE.Can - v1.08

* SmartSolar Charger MPPT 150/85 rev2 - v1.53

* Quattro 12/5000/220-2x75 - v474 Product ID 2633

* CCGX - v2.53

* VE.Bus BMS


Per the advice of the Victron certified installer I have deeply discharged the battery bank to 30% SOC per the CCGX display dropping voltage to 12.8v while under some load and charged it back to 14.2v and absorption. The cells do not appear to be coming up in line with the rest of the cells in the battery.


Any ideas on how to resolve this issue?


Thanks

Lithium Batterybattery charging
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1 Answer
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Jon S

1st. make sure the batteries have the latest firmware installed

2nd. leave the batteries fully charged at 14.2 volts until they are fully balanced.

3rd. after fully balanced, discharge and charge again, cells should still be quickly balanced again.

4 comments
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@Daniël Boekel (Victron Energy Staff)


The batteries are all running Firmware v1.19 and boot loader v.1.06. I am currently at a dock and connected to shore power. The batteries have been at 100% for a week. I do unplug from time to time to drop them off 100% and discharge down to 80%. I plug back in over night so am at 100% in the morning. I have been on the dock for 3 weeks. I still have the issue that these 2 cells will not balance.


How long should I leave the batteries at 14.2. The charger goes into float after 2 hours of absorption and stays in float. Are you suggesting I change float voltage to 14.2 until these cells balance?

Thanks!


Jon

Hi @Jon S

As written: leave at 14.2 volts until fully balanced.

this is also in the manual:


https://www.victronenergy.com/media/pg/15958-Lithium_Battery_Manual-html5/en/installation.html#UUID-b9db9949-14ce-5b04-399f-1c5c35fca580


note that when all batteries are parallel (like your 12V system) you can do this balance charging with all batteries connected.

Jon S avatar image Jon S Daniël Boekel (Victron Energy Staff) ♦♦ ·

@Daniël Boekel (Victron Energy Staff)

Hi. Sorry for delay I wanted to take the boat off the dock to see how the battery was behaving not connected to the dock power.


I did as described and ran the charger until absorption completed then restarted absorption until battery was balanced. This took restarting absorption 1 time. The cells were all at 3.55.

I am now seeing consistently the second condition I described which is once the batteries get up to about (it varies) 14v cell 4 races to 3.76v then bms cuts charging. This happens until the battery reaches 14.2 then goes into absorption. Once in absorption it is out of balance with cell 4 now at 3.71v. The other cells are at 3.42, 3.42, 3.57.

The cells were perfectly balanced at 3.55 for each cell prior to this current situation.


Any ideas? I didn’t want to run more in absorption than necessary to balance them. Since 14.2 is not the top voltage for Winston cells I was wondering if I need to raise the voltage to truly balance them.


thanks


Hi @Jon S I'd try lowering the abs. voltage a little (14-14.1 volt?) to see if that helps.

If this doesn't help please contact your dealer for a solution.