2 12v batteries in series(24v) being charged individually @12v?

[73powerstroke]

What would happen if you had two 12 volt batteries hooked to two different solar panels and charge controllers but the batteries were in series powering a 24 volt inverter?
Would this work? Or would weird things happen under load.

 

[cs1234]

It should work fundamentally.

I have some 12v batteries connected in 24v series, and then have a 12v multiport balancer/equalizer attached to them on their individual posts. I've also hooked up 10 and 30 amp 12v chargers to the individual batteries from time to time. Works fine, haven't experienced anything strange under load, but I don't really stress them to maximum charge/discharge rates of their BMS either.

 

[73powerstroke]

It should work fundamentally.

I have some 12v batteries connected in 24v series, and then have a 12v multiport balancer/equalizer attached to them on their individual posts. I've also hooked up 10 and 30 amp 12v chargers to the individual batteries from time to time. Works fine, haven't experienced anything strange under load, but I don't really stress them to maximum charge/discharge rates of their BMS either.

Im curious because I have a balancing issue sometimes. Until i can afford better batteries than fla walmart batteries. Technically im still experimenting and trying to figure out what system works for me and really I've only been doing this for about a year now
There's definitely made some poor choices and wasted money on things that I didn't need and squandered money in places where I needed to spend but all I'm really running is a 500 w air conditioner using a hvlv 2424 it just seems to do weird stuff so I thought maybe I could take some of my 40 amp charge controllers and charge each battery individually from a group of solar panels

 

[sunshine_eggo]

Im curious because I have a balancing issue sometimes. Until i can afford better batteries than fla walmart batteries. Technically im still experimenting and trying to figure out what system works for me and really I've only been doing this for about a year now
There's definitely made some poor choices and wasted money on things that I didn't need and squandered money in places where I needed to spend but all I'm really running is a 500 w air conditioner using a hvlv 2424 it just seems to do weird stuff so I thought maybe I could take some of my 40 amp charge controllers and charge each battery individually from a group of solar panels

Many marine chargers in 24, 36 and 48V variations simultaneously charge the individual 12V that are in series. They are crazy expensive, but as @cs1234 indicates, you should be able to attach two separate 12V chargers to the 12V in your 24V bank.

 

[73powerstroke]

Many marine chargers in 24, 36 and 48V variations simultaneously charge the individual 12V that are in series. They are crazy expensive, but as @cs1234 indicates, you should be able to attach two separate 12V chargers to the 12V in your 24V bank.

Do you think i can run 2 group 24 walmart dc batteries in series to my mpp hvlv2424 and have a 40a charge controller on it and safely run a 500w ac unit. Sometimes i run a second 600w unit also

 

[sunshine_eggo]

Do you think i can run 2 group 24 walmart dc batteries in series to my mpp hvlv2424 and have a 40a charge controller on it and safely run a 500w ac unit. Sometimes i run a second 600w unit also

So you're proposing using 2X 40A MPPT on each 12V wired in series for 24V.

Assuming you have overpaneled each a bit (+30%), you could come close to running both, one for sure.

Would also expect to use the LV2424 MPPT, but you could set that at a lower level like 27V to kick in only when the 40A can't keep the 12V @ absorption/float.

in fact, I would reverse that concept.

Use the LV2424 MPPT to its fullest, but only at a float voltage where it won't cause the individual 12V to exceed 12V absorption voltage. THEN use the 40A for absorption/full charge on each 12V.

This is mickey-mousey, but I think there's a workable solution in there.

 

[cs1234]

Im curious because I have a balancing issue sometimes. Until i can afford better batteries than fla walmart batteries. Technically im still experimenting and trying to figure out what system works for me and really I've only been doing this for about a year now
There's definitely made some poor choices and wasted money on things that I didn't need and squandered money in places where I needed to spend but all I'm really running is a 500 w air conditioner using a hvlv 2424 it just seems to do weird stuff so I thought maybe I could take some of my 40 amp charge controllers and charge each battery individually from a group of solar panels

Balancing issues aren't unusual when using multiple batteries in series. For 12v batteries in series, I use and recommend one of these. I have the four port one, but the two port one probably works just as well for two batteries.

 

[73powerstroke]

So you're proposing using 2X 40A MPPT on each 12V wired in series for 24V.

Assuming you have overpaneled each a bit (+30%), you could come close to running both, one for sure.

Would also expect to use the LV2424 MPPT, but you could set that at a lower level like 27V to kick in only when the 40A can't keep the 12V @ absorption/float.

in fact, I would reverse that concept.

Use the LV2424 MPPT to its fullest, but only at a float voltage where it won't cause the individual 12V to exceed 12V absorption voltage. THEN use the 40A for absorption/full charge on each 12V.

This is mickey-mousey, but I think there's a workable solution in there.

The wal mart batteries keep failing slowly. I think they are being over charged.
I just got 2 more new ones warranty replacement.

I have 10 panels on one charge controller and 10 on another. 2 series 5 p i guess. I have a 3rd group of 6 panels 2s3p.
Most get sun all day till 5pm
Originally I noticed issues with the mpp hvlv2424 so i let the tracers handle everything and just used the mpp hvlv2424 to invert only

 

[73powerstroke]

Balancing issues aren't unusual when using multiple batteries in series. For 12v batteries in series, I use and recommend one of these. I have the four port one, but the two port one probably works just as well for two batteries.

View attachment 155043

How much current are most of these design to handle?
I seems like my epevers and mpp solar hv lv2424 are over charging these poor walmart batteries to death

 

[cs1234]

How much current are most of these design to handle?
I seems like my epevers and mpp solar hv lv2424 are over charging these poor walmart batteries to death

They take current from the batteries with higher voltage and move it to the lower voltage batteries. The 4 port one does up to 10amps of balancing, the 2 port one does up to 5 amps.

The balancers can't overcharge a battery if they are all the same type of battery.. it's only moving current around that is already on the circuit.. either from chargers or the batteries themselves.

 

[73powerstroke]

They take current from the batteries with higher voltage and move it to the lower voltage batteries. The 4 port one does up to 10amps of balancing, the 2 port one does up to 5 amps.

The balancers can't overcharge a battery if they are all the same type of battery.. it's only moving current around that is already on the circuit.. either from chargers or the batteries themselves.

Ok i see. Any time the solar is charging the batteries they are under load running the window ac unit. So i was for some reason thinking the unit was in between the cc and batteries. I see now. So it just keeps them balanced. I dont think this is the real problem with the walmart deep cycle batteries. But im sure it would help.
I dont think these batteries like to see more than 14v so i think the settings for fla are too hot for these cheap automobile batteries.
I have went through 3 sets in 1 year. They used to be $79 a batteries (group 24dc) but now they are 89
It was a real hassle getting them replaced yesterday. They tested bad no problem. But the paperwork and the reciepts and stuff. And waiver of core charges too over a hour to get done. So i have 2 brand new group 24 batteries in the truck that i think om better off trying to sell on Craigslist for $100 for the pair and stop while im ahead. Right now im using two older batteries from my truck that are group 65 automobile batteries. Probably just as good. And since i dont use the system when the sun goes down or solar production drops below the load i should be fine. They should just act as filter capacitors lol ?

 

[JWLV]

Fact is lead acid batteries and even deep cycle marine batteries really suck for solar. Replacing them three times in one year is about right.

 

[73powerstroke]

Fact is lead acid batteries and even deep cycle marine batteries really suck for solar. Replacing them three times in one year is about right.

I geuss so. I figured ive seen car batteries last 8 years. I figured i would get at least 2 years from deep cycle batteries. I dont discharge them when there is no solar. So the worst they see is the sun starts to get low and solar cant keep up with the load and i turn off load. I never run any load after dark

 

[73powerstroke]

I think im just going to run used junk truck batteries for a while. The solar doesnt seem to care

 

[73powerstroke]

So far my old junk batteries are working. I wonder ifci can just use 2 really big capacitors instead for a battery less system?