Who makes these batteries, and which would you recommend?

[jieiku]

No, not for no reason. I wired all four of them up in series to a 48V inverter, and they are not charging to the same voltage. I tried this for a good amount of time, you can see that there was a month to my previous post. This is because they are unbalanced, and the internal resistance obviously plays a factor. After I do this to all four batteries the internal resistance will likely be matched well, and all the batteries will have been equalized.

Previously I used a 24 volt inverter and had 2 in series, it was like that for 5 years and they always charged at exactly the same voltage, never an issue and I would check them twice a year, those are the older batteries mentioned in this thread. ( I just recently upgraded to a 48 volt system, the old 24 volt system will be going to my mother, the batteries from that system still work like new. )

If I absolutely have to I will get a battery management system, or individual battery tenders so that I can keep the battery bank balanced.

This is all important because if I simply wire them up to the inverter/charger then some of them will sit at 12.5 volt while others sit at 14.5 volts, this is because the bank is unbalanced. Even if I were not having this issue of an unbalanced battery bank, having a good equalization charge should help the health of the batteries in the long run.

 

[meep]

I see what you are trying to do. When running in series you almost have to buy them all at the same time. You can then temporarily wire them in parallel to give them a finishing charge, then install them in series for your inverter use. If they are run in series with different ages, effective capacities and self-discharge rates, one will always be undercharged while the other is overcharged, reducing final capacity and pack lifespan.

 

[jieiku]

I bought all 4 on the same day, and they are all within a few months of each other. ideally they would have all had exactly the same manufacture date. I will be sure to follow up again after I have them all 4 hooked up to the inverter again. I may follow up 6months after that too if I can remember to. What I did to this first battery certainly improved its internal resistance number according to my tester. I am hopeful that it will work out just fine. (takes me about a day to do this procedure to a battery assuming they are already charged up, so by the end of the week I should have them hooked back up)