EG4 48v WP batteries balance problem

[Trkarl]

I purchased 3 eg4 48v 100 ah waterproof batteries from Signature Solar in March of 2022. They have been in service since then daily. At first they were not balanced at all. Slowly over the months they balanced out okay. I also run them parallel with a diy 304 ah battery with a jk bms that works flawlessly. Daily I monitor
everything especially when the batteries are absorbing to check the balancing and voltage of all my cells. Everything has run perfect for 2 years.

I was out of town for 10 days so the system charged and then floated for several hours every day. Today when I checked all my batteries while absorbing each of my eg4 batteries was extremely out of balance. Surprisingly each one had 2 cells at 3.67v and several cells at 3.35v. They were not this far out of balance when I first got them. How can they go this far out of balance in 10 days especially when for several days in a row they were able to absorb and balance?

My settings are bulk to 55.2v, absorb @ 55.2v for 1 hour, float @ 54v . My charge controllers are Victron Smart Solar 150/70 and 150/60. I checked the logs and each day they did what they have always done.

My concern is the cells getting over 3.65v . The spec sheet says over voltage protection from the bms is set at 3.9v which seems too high. Any ideas how this could happen? Maybe I should just buy 3 jk bmses and replace them before the cells are ruined.

 

[sunshine_eggo]

I purchased 3 eg4 48v 100 ah waterproof batteries from Signature Solar in March of 2022. They have been in service since then daily. At first they were not balanced at all. Slowly over the months they balanced out okay. I also run them parallel with a diy 304 ah battery with a jk bms that works flawlessly. Daily I monitor
everything especially when the batteries are absorbing to check the balancing and voltage of all my cells. Everything has run perfect for 2 years.

I was out of town for 10 days so the system charged and then floated for several hours every day. Today when I checked all my batteries while absorbing each of my eg4 batteries was extremely out of balance. Surprisingly each one had 2 cells at 3.67v and several cells at 3.35v. They were not this far out of balance when I first got them. How can they go this far out of balance in 10 days especially when for several days in a row they were able to absorb and balance?

It's not clear to me that you are comparing the values at day 0 and after 10 days. Are you saying before you left town, they were all at 3.45V @ 55.2V and 3.375V @ 54.0V?

My settings are bulk to 55.2v, absorb @ 55.2v for 1 hour, float @ 54v . My charge controllers are Victron Smart Solar 150/70 and 150/60. I checked the logs and each day they did what they have always done.

My concern is the cells getting over 3.65v . The spec sheet says over voltage protection from the bms is set at 3.9v which seems too high. Any ideas how this could happen? Maybe I should just buy 3 jk bmses and replace them before the cells are ruined.

3.67 vs. 3.65 is a non-issue. I would see how they behave over several more days of normal operation.

If your system was utilized less in your absence, then maybe the absorption period resulted in less balancing than what you might get with more charging due to higher utilization. One would hope that this wouldn't matter over 10 days.

 

[Trkarl]

It's not clear to me that you are comparing the values at day 0 and after 10 days. Are you saying before you left town, they were all at 3.45V @ 55.2V and 3.375V @ 54.0V?



3.67 vs. 3.65 is a non-issue. I would see how they behave over several more days of normal operation.

If your system was utilized less in your absence, then maybe the absorption period resulted in less balancing than what you might get with more charging due to higher utilization. One would hope that this wouldn't matter over 10 days.

The cells have stayed within about 50mv or less deviation for almost 2 years now. The balancer in these batteries balances only on greater than a 40mv deviation so that is probably why they never get much closer in balance. Usually and day 0 the high cell may be 3.50v @ 55.2v. By day 10 now each battery has cells that are 3.67 and cells that are 3.35v at 55.2v . Thats over 300mv deviation.

You are probably right that higher utilization will balance them as it did when I first got them. Thanks for the reply. I will keep watching them.