Charging batteries in a bank separately

[tylarson]

Can I put two 24 volt batteries in series to have 48 volts going to the inverter but charge them separately at 24 volts? The 24 volt batteries are similar but not exactly the same. Thank you in advance for the help.

 

[BentleyJ]

Can I put two 24 volt batteries in series to have 48 volts going to the inverter but charge them separately at 24 volts?

Maybe, see below

The 24 volt batteries are similar but not exactly the same. Thank you in advance for the help.

"Similar" is extremely vague compared to posting some actual datasheet specifications of the batteries in question. We would be happy to help but most of us are not psychic. I believe the well known computer saying applies here. "garbage in, garbage out".

 

[tylarson]

Maybe, see below

"Similar" is extremely vague compared to posting some actual datasheet specifications of the batteries in question. We would be happy to help but most of us are not psychic. I believe the well known computer saying applies here. "garbage in, garbage out".

My question is hypothetical, I believe that batteries in series if they are not identical charge at different rates which makes it a bad idea. So hypothetically if batteries were charged separately perhaps it doesn't matter if they are not identical

 

[BentleyJ]

So yes, electrically speaking they can be charged with 2 independent chargers in the same manner as a BMS can charge or discharge individual cells connected in series in a battery but as you pointed out there are lots of potential problems to such an arrangement.

 

[tylarson]

There are a lot of very smart people on this forum, and I am simply trying to learn what can and can't be done with batteries.

 

[tylarson]

Thank you for your response, I found a similar thread on this forum also which was helpful

 

[Madcodger]

Just seeing this. FWIW, I once had four 12V batteries wired in series to produce 48V. I recharged them several times per year with four 12V chargers, connected one to each battery. Never seemed to cause a problem.

 

[teal95]

I've done this with my golf cart (6x 8v batteries). I do this at least once a year to balance them. However I'm fully charging them first and then only doing this to balance them.

 

[tylarson]

Just seeing this. FWIW, I once had four 12V batteries wired in series to produce 48V. I recharged them several times per year with four 12V chargers, connected one to each battery. Never seemed to cause a problem.

I have no idea why I did not see this post earlier. But thank you for the post, did you run a separate charger to each battery while they were still connected in series?

 

[tylarson]

So here's my dilemma, it would be fun to set up a second system in the garage, with parts that have been gathering dust for a while. I already have a 48v 7,000 watt inverter and two Outback charge controllers, and a couple strings of solar panels. and two enormous 24 volt lead acid forklift batteries. One battery is a little bit bigger than the other one. My thought is to put the two batteries in series, and run a separate Outback to each one to charge them. I realize the batterys not being identical is not ideal. I could buy a 24 volt inverter that would go with the batteries or I could buy 48volt batteries to go with the inverter I already have but I'm just having fun trying to make use of parts that I already have. I realize you guys have already answered this question, but I'm trying to get a feeling for whether it might work or it's simply a bad idea and probably won't work. really appreciate your comments everybody and your expertise.

 

[Madcodger]

I have no idea why I did not see this post earlier. But thank you for the post, did you run a separate charger to each battery while they were still connected in series?

I did, and it worked fine for me. I haven't had that system hooked up for about 4-5 years now, but it got us through several storms and outages. Basically, I had an old server UPS that formerly used a 48V battery. I just yanked that out and rewired it with the four marine batteries. Because I didn't have a 48V charger, but had found a great deal on four 12V chargers, I just connected one to each of the four batteries and plugged them all into a big charging strip. Worked for me.

 

[tylarson]

I did, and it worked fine for me. I haven't had that system hooked up for about 4-5 years now, but it got us through several storms and outages. Basically, I had an old server UPS that formerly used a 48V battery. I just yanked that out and rewired it with the four marine batteries. Because I didn't have a 48V charger, but had found a great deal on four 12V chargers, I just connected one to each of the four batteries and plugged them all into a big charging strip. Worked for me.

Thank you very much for the response.