Balancing Battle Born batteries in 24 volt series

tucsonjwt · Sep 8, 2023

I have an MPP Solar 24 volt all in one inverter connected to 12 volt Battle Born batteries wired in series (4 batteries total, 2 strings of 2 12 volt batteries.)
The system has been working fine for about one year but I had the batteries go dead overnight. I recharged the batteries individually and reconnected them in series and they went dead overnight again.

I contacted MPP solar and was told that I need to add a battery balancer to the battery bank. I have seen a video from Battle Born on YouTube explaining that Battle Born batteries do not need an external balancer.

I suspected that the inverter was no longer charging the batteries but MPP said it was a battery balancing problem.

I did originally top balance the batteries before connecting them to the inverter.

Does anyone have advice on how to proceed? I am OK with installing external balancers if that will fix the problem. I have a call in to Battle Born but have not received a response yet.

Thanks

mikefitz · Sep 8, 2023

There have been reports of internal connection issues that can result in the batteries not charging correctly .

.https://diysolarforum.com/threads/battleborn-four-bb10012-battery-bank-failure.67472/#post-851835

MiSh · Sep 8, 2023

tucsonjwt said:
I have an MPP Solar 24 volt all in one inverter connected to 12 volt Battle Born batteries wired in series (4 batteries total, 2 strings of 2 12 volt batteries.)
The system has been working fine for about one year but I had the batteries go dead overnight. I recharged the batteries individually and reconnected them in series and they went dead overnight again.

I contacted MPP solar and was told that I need to add a battery balancer to the battery bank. I have seen a video from Battle Born on YouTube explaining that Battle Born batteries do not need an external balancer.

I suspected that the inverter was no longer charging the batteries but MPP said it was a battery balancing problem.

I did originally top balance the batteries before connecting them to the inverter.

Does anyone have advice on how to proceed? I am OK with installing external balancers if that will fix the problem. I have a call in to Battle Born but have not received a response yet.

Thanks

When you first recharged the batteries, what charger did you use and how did you know they were completely charged? Can you put a clampmeter on the battery cable to see if it's actually taking a charge? Also, if there's a problem with the batteries taking a charge, I doubt a balancer is going to solve the issue. I never heard of BB advising to use one. I have 10 BBs in series/parrallel and never needed one. But BB does recommend charging each battery individually every few months or so.

tucsonjwt · Sep 8, 2023

Thanks for the response. I did get a voicemail from Battle Born, which confirmed that an external battery balancer is not needed. I did charge the batteries to 100% full state of charge (individually) using a Battle Born recommended Victron LFP battery charger. I am recharging them now for the second time and will put a clamp meter on the output cables from the MPP inverter. (I did not think to check that when I hooked them up for the second time yesterday because the MPP display looked normal with no fault codes.) I do have a question on that. I need to connect the batteries in order for the inverter to send power to the batteries, but if the batteries are connected how do I know if I am checking power coming from the batteries to the inverter or from the inverter to the battery. Won't I just have a reading of voltage going through the line with no definition of whether it is coming from the inverter or going to the inverter? I know that is a dumb question but I am not very smart.

I have another call into Battle Born to confirm my understanding of the issue.

I have watched videos on YouTube which show that two batteries showing the same voltage with a volt meter have a slightly different voltage displayed on an equalizer when they are hooked up to it.

MiSh · Sep 9, 2023

tucsonjwt said:
Thanks for the response. I did get a voicemail from Battle Born, which confirmed that an external battery balancer is not needed. I did charge the batteries to 100% full state of charge (individually) using a Battle Born recommended Victron LFP battery charger. I am recharging them now for the second time and will put a clamp meter on the output cables from the MPP inverter. (I did not think to check that when I hooked them up for the second time yesterday because the MPP display looked normal with no fault codes.) I do have a question on that. I need to connect the batteries in order for the inverter to send power to the batteries, but if the batteries are connected how do I know if I am checking power coming from the batteries to the inverter or from the inverter to the battery. Won't I just have a reading of voltage going through the line with no definition of whether it is coming from the inverter or going to the inverter? I know that is a dumb question but I am not very smart.

I have another call into Battle Born to confirm my understanding of the issue.

I have watched videos on YouTube which show that two batteries showing the same voltage with a volt meter have a slightly different voltage displayed on an equalizer when they are hooked up to it.When you

When you say that the batteries went dead, twice, overnight, was there a load on them overnight? You should be able to use a multimeter on the batteries while the MPP charger is on to see if your batteries are getting any charge to them.

mikefitz · Sep 9, 2023

tucsonjwt said:
put a clamp meter on the output cables from the MPP inverter

The meter will display current direction, test on a known current direction to a load to determine clamp meter orientation.

The internal poor connection may eventually fail in all Battleborn batteries, this could be your issue. Under pressure Batlleborn will replace under warranty. Check the positive terminal on the battery for intermittent Inernal connection and possible overheating.

Skypower · Sep 9, 2023

At this point it’s hard to say. It seems like the inverter didn’t charge. If you managed to manually charge the battery individually that might rule out the batteries. If you aren’t there to monitor or see event history, it’s guessing and flying blind. A DC clamp meter is nice, will work, however always auto-off and eating batteries. It’s much better if you have a good battery capacity meter hardwired in place. There’s many meters. The top of the line and priciest is the Victron smart shunt that has an app however if you want a display, that’s more money. I’m a bit of a tinker so I buy stuff to try. I won’t even name them because they are rebranded by many. The best inexpensive monitor and incredibly accurate is the one with the blue vertical battery symbol with a Bluetooth nice app. The drawback is the charge discharge symbol is small, red for charge and blue for discharge and capacity is only in amp hours not the preferred kWh’s. The newer slightly more expensive version has a horizontal displayed battery symbol and plus or minus for charge status. Unfortunately this version’s current can only be set with zero current which is good if you don’t have an accurate DC current clamp meter but isn’t the best I’ve found for ultimate precision. I’ve used the Hall effect type (turquoise frame) and it was accurate enough until the voltage reading drifted off actual voltage and there was no way to recalibrate like the two forementioned types. So after a year of service it was retired. There was a smaller black framed version that had passable accuracy but a poorer display. Then there is the black framed, shunt type that is reasonably accurate but outright infuriating to program or reset with only a single button.