4-battery bank; one battery is warm

[Daddy Tanuki]

I’m not sure I understand your remarks. I also use premade batteries with their own internal bms. The internal bms of a battery does nothing to balance each battery that is in a series string. Each individual battery must be at the same state of charge as the others for the 48v pack to produce its full ah rating. The individual bms of the battery will not balance the batteries in relation to each other only the cells inside the battery that are monitored by the bms and in some cases (it happened to me) the internal bms doesn’t even balance the internal cells of the battery. Perhaps you did not catch that we were discussing a battery bank that is a series configuration?

you are treating it like a DIY pack with a BMS. the batteries, if they can be used in series or in parallel, (depends upon maker and internal BMS) will self level between 12 volt batteries under normal use, if they are not its a physical buss bar/connection issue.

Which is what you basically said.

When you go into trying to balance 4 /12 volt batteries that are wired in series for 48 that's when you went off the deep end. I suppose somebody sells a balancer for this but being that you can tie any normal four 12 volt batteries into series and not have an issue I would call it a non problem... he has a connection issue, or his batteries internal BMS cannot handle being wired into series.

get with the program is a Marine Corp saying designed to F with your head. Get with the Program

 

[Bobert]

you are treating it like a DIY pack with a BMS. the batteries, if they can be used in series or in parallel, (depends upon maker and internal BMS) will self level between 12 volt batteries under normal use, if they are not its a physical buss bar/connection issue.

Which is what you basically said.

When you go into trying to balance 4 /12 volt batteries that are wired in series for 48 that's when you went off the deep end. I suppose somebody sells a balancer for this but being that you can tie any normal four 12 volt batteries into series and not have an issue I would call it a non problem... he has a connection issue, or his batteries internal BMS cannot handle being wired into series.

get with the program is a Marine Corp saying designed to F with your head. Get with the Program

Have you ever put 4 12v lifepo4 batteries with individual bms together when one of the batteries has a significant difference in state of charge and had the pack balance itself?

 

[Daddy Tanuki]

Have you ever put 4 12v lifepo4 batteries with individual bms together when one of the batteries has a significant difference in state of charge and had the pack balance itself?

as I said they either can or cannot work together that was one of the caveats.. you make it sound like you need a secondary BMS.. you do not you simply charge them all to full charge as allowed by their internal BMS and go from there treating them as an individual battery... they either work, or they do not depending upon their internal BMS architecture. Hence as said before if the maker allows for series hookup.

 

[Panderson03]

There seems to be a little tension here, so let me try and divert the discussion back to the original topic.
We successfullly re-balanced our 4 batteries and reintroduced them to our system. Unfortunately battery #3 (as we now fondly call the failing battery) continues to fail to keep in pace with the other healthy 3 (volt differences; battery surface temperature differences) batteries. We've reached out to Northern Arizona for next steps.

I really appreciate the counsel of this learned group

 

[Bobert]

as I said they either can or cannot work together that was one of the caveats.. you make it sound like you need a secondary BMS.. you do not you simply charge them all to full charge as allowed by their internal BMS and go from there treating them as an individual battery... they either work, or they do not depending upon their internal BMS architecture. Hence as said before if the maker allows for series hookup.

Yes however in this case we have a pack that was put together with one battery substantially more charged than the other 3. The user doesn’t have a means to fully charge the batteries before assembly.

There seems to be a little tension here, so let me try and divert the discussion back to the original topic.
We successfullly re-balanced our 4 batteries and reintroduced them to our system. Unfortunately battery #3 (as we now fondly call the failing battery) continues to fail to keep in pace with the other healthy 3 (volt differences; battery surface temperature differences) batteries. We've reached out to Northern Arizona for next steps.

I really appreciate the counsel of this learned group

good idea these batteries should not walk away from each other once they are all in the same state of charge.

 

[Bobert]

Yes however in this case we have a pack that was put together with one battery substantially more charged than the other 3. The user doesn’t have a means to fully charge the batteries before assembly.

good idea these batteries should not walk away from each other once they are all in the same state of charge.

I stand corrected the user now does have a means of individualy charging the battery and it looks like a solution is on the way. Best wishes.

 

[Willdem71]

Hello! We finally were able to finish set up on our epanel and get our solar array (9 370watt panels) connected to our 4 LiFePO4 batteries (12V/206 AMP connected in series ). HURRAY for us! But when charging, one of the 4 batteries becomes much warmer than the others. Is this normal or should i be worried?

thank you

Hey guys. I have a similar problem. I am running 8 x 200Ah Gel batteries, 2 sets of 4 batteries in series, connected in parallel. I noticed that the 2nd battery in the first bank was much warmer than all of the others, but only on the front corner. the opposite side of the battery is cooler. I noticed this during the night, and I'm not sure if it got hot during the charging cycle and is cooling down. I am monitoring it constantly. I have had these batteries for over 6 months, and I was wondering if it is good practice just to replace that one battery with a brand new identical battery, or, do I need to change all 8 of them?

 

[Daddy Tanuki]

Hey guys. I have a similar problem. I am running 8 x 200Ah Gel batteries, 2 sets of 4 batteries in series, connected in parallel. I noticed that the 2nd battery in the first bank was much warmer than all of the others, but only on the front corner. the opposite side of the battery is cooler. I noticed this during the night, and I'm not sure if it got hot during the charging cycle and is cooling down. I am monitoring it constantly. I have had these batteries for over 6 months, and I was wondering if it is good practice just to replace that one battery with a brand new identical battery, or, do I need to change all 8 of them?

first check your connections... heat in one location points to a less than optimal connection...pull wire brush anti oxident paste and properly torque.. then watch it for a few days. Prior to my swap over to LiFePo4 cells I was using AGM's in a 4S3P setup 4 series to produce 48 and then three banks in parallel. I developed a hot spot on one bank where I had not cleaned the terminal as well as I thought... and it got very warm. a wirebrush, some anti oxident paste fixed it.

 

[Willdem71]

first check your connections... heat in one location points to a less than optimal connection...pull wire brush anti oxident paste and properly torque.. then watch it for a few days. Prior to my swap over to LiFePo4 cells I was using AGM's in a 4S3P setup 4 series to produce 48 and then three banks in parallel. I developed a hot spot on one bank where I had not cleaned the terminal as well as I thought... and it got very warm. a wirebrush, some anti oxident paste fixed it.

Thanks for that. I just wanted to clarify that my batteries are Gel batteries. I have 2 banks of 4, and only one battery is getting hot, on the front left side (it's the second battery from the end). I think it might be an issue with one of the cells in that battery, but as they are sealed, I cannot just open them. Do you still think I should disconnect the battery and clean the terminals, check the cables and reconnect the battery?

 

[Daddy Tanuki]

Thanks for that. I just wanted to clarify that my batteries are Gel batteries. I have 2 banks of 4, and only one battery is getting hot, on the front left side (it's the second battery from the end). I think it might be an issue with one of the cells in that battery, but as they are sealed, I cannot just open them. Do you still think I should disconnect the battery and clean the terminals, check the cables and reconnect the battery?

move it to tail end charlie to and clean the terminals and retorque. changing location changes quite a few things. the cleaning of the terminals will eliminate them from the equation... at the very worse it acts just like it did before and that would mean a battery issue.

 

[HRTKD]

Cleaning and refastening the connection costs you nothing. Way cheaper than a new battery.