Hooking up SOK batteries of different amperage in parallel

[Hikerguy]

I have 2 100 AH SOK 12v batteries I want to hook up in parallel with a 206 AH SOK battery for 406 AH total at 12v, which I then want to hook up in series with 2 206 AH 12v SOKs which are connected in parallel so I can have a 24 v system with 818 AH to connect to my 3000W Growatt 24v controller/inverter.

I know ideally I should use 4 206 batteries, but that is not what I have. Will this work since all the batteries have their own BMS?

 

[rmaddy]

FYI - If you were to have 4 206Ah batteries hooked in 2S2P, you would have 412Ah @ 24V, not 824Ah @ 24V. Remember, in series you add the volts and keep the amps the same. In parallel you add the amps and keep the volts the same.

So even if you can manage to combine the 2 100Ah batteries and the 3 206Ah batteries as you describe you would end up with roughly 406Ah @ 24V, not 818Ah @ 24V.

There are some threads on this site about connecting batteries of different amp-hours in parallel. See if you can find them through some searching.

But I highly doubt you could connect the mismatching battery sets in series to make a 24V system without lots of issues. Batteries is series need to be matched very close in voltage and SOC. Trying to combine the 406Ah string (made of the 2 100Ah and 1 206Ah) with the 412Ah string (made of the 2 206Ah) will never balance. You are likely just going to ruin one or two of the batteries over time due to over charge and discharge while others never fully charge properly.

 

[Hikerguy]

Thanks so much for your reply! I had heard the BMS in each battery would insure proper charging/discharging. Once one get charged it shuts down and passes the current along. "Highly doubt" and "likely" are somewhat helpful but I hope someone could give me a definite answer as I've read both it won't hurt and it "might" hurt but probably not since they are not lead acid.

 

[Hikerguy]

Please disregard. I sold my one 100AH SOK battery and SOK is canceling my order for another 100AH battery and I'm buying another 206 AH SOK battery so I will have 4 12v 206 AH SOK batteries to hook up 2 pairs in parallel then hook up each pair in series for 24 volts.

 

[rmaddy]

Good plan! 412Ah @ 24V is great. I have two 206Ah SOK connected for 24V with a 2000W inverter. Runs my 5000BTU A/C nice and easy.

 

[solar kid]

I have 2 100 AH SOK 12v batteries I want to hook up in parallel with a 206 AH SOK battery for 406 AH total at 12v, which I then want to hook up in series with 2 206 AH 12v SOKs which are connected in parallel so I can have a 24 v system with 818 AH to connect to my 3000W Growatt 24v controller/inverter.

I know ideally I should use 4 206 batteries, but that is not what I have. Will this work since all the batteries have their own BMS?

get another cc and keep the battery sets seperate

 

[CravinR1]

FYI - If you were to have 4 206Ah batteries hooked in 2S2P, you would have 412Ah @ 24V, not 824Ah @ 24V. Remember, in series you add the volts and keep the amps the same. In parallel you add the amps and keep the volts the same.

So even if you can manage to combine the 2 100Ah batteries and the 3 206Ah batteries as you describe you would end up with roughly 406Ah @ 24V, not 818Ah @ 24V.

There are some threads on this site about connecting batteries of different amp-hours in parallel. See if you can find them through some searching.

But I highly doubt you could connect the mismatching battery sets in series to make a 24V system without lots of issues. Batteries is series need to be matched very close in voltage and SOC. Trying to combine the 406Ah string (made of the 2 100Ah and 1 206Ah) with the 412Ah string (made of the 2 206Ah) will never balance. You are likely just going to ruin one or two of the batteries over time due to over charge and discharge while others never fully charge properly.

If you parallel the 2x 100ah to make a 200ah 12v and then parallel/series the main leads of that battery to the 3x206ah battery it would be seen as a 200ah battery so you would have 2x400ah 24v.

 

[rmaddy]

If you parallel the 2x 100ah to make a 200ah 12v and then series the main leads of that battery to the 3x206ah battery it would be seen as a 200ah battery so you would have 4x 200ah 24v.

I don't follow your logic or understand what your final result means. Combining a 12V 200Ah battery in series with a 12V 618Ah battery does not result in a 24V 800Ah battery (if that's what you meant by 4x 200Ah). In series you add the voltage but the amps stay the same. In parallel you add the amps but keep the voltage the same. And all of this ignore the fact that when putting batteries in series they really need to be the same capacity (Ah) and they must be at the same SOC (state of charge). If would be a big problem to put a 12V 200Ah battery in series with a 12V 618Ah battery.

But that's not what the OP was describing and what I was answering. The OP wanted to combine the 2 12V 100Ah and 1 of the 12V 206Ah batteries in parallel making a 12V 406Ah battery. Then combine the other 2 12V 206Ah in parallel making a 12V 412Ah battery. Then combine those two in series which would make a 24V 406ishAh battery.

 

[CravinR1]

I reread op thought he was trying to get a 48v so it wouldn't work

 

[CravinR1]

I don't follow your logic or understand what your final result means. Combining a 12V 200Ah battery in series with a 12V 618Ah battery does not result in a 24V 800Ah battery (if that's what you meant by 4x 200Ah). In series you add the voltage but the amps stay the same. In parallel you add the amps but keep the voltage the same. And all of this ignore the fact that when putting batteries in series they really need to be the same capacity (Ah) and they must be at the same SOC (state of charge). If would be a big problem to put a 12V 200Ah battery in series with a 12V 618Ah battery.

But that's not what the OP was describing and what I was answering. The OP wanted to combine the 2 12V 100Ah and 1 of the 12V 206Ah batteries in parallel making a 12V 406Ah battery. Then combine the other 2 12V 206Ah in parallel making a 12V 412Ah battery. Then combine those two in series which would make a 24V 406ishAh battery.

So answer me this. Why can't you:
100ah + 100ah 12v parallel = 200ah 12v = battery 1
battery 2-3 = 206ah 12v

Series 2x 206ah 12v = 206ah 24v = series 1
series 1x206ah + 1x200ah (100ah+100ah bat 1) = 200ah 24v = series 2

Parallel Series 1 + series 2 = 24v 400ah

Parallel connecting the 100ah batteries makes them a 200ah 12 volt battery. Add the parallel main terminals into series with a 206ah battery will make that series a 200 ah 24v

Series connect the other 2x 206ah batteries for a 206ah 24v battery

Parallel series 1 (parallel 100ah x2 + 206ah) and seires 2 (2x 206ah) for a 400 (or is it 406)ah 24v battery

 

[rmaddy]

series 1x206ah + 1x200ah (100ah+100ah bat 1) = 200ah 24v = series 2

I just don’t think it’s a good idea to try to series like this. Batteries in series should be identical and at the same state of charge. If not then things will get out of balance and the separate batteries will get charged and discharged at different rates and eventually one will fail.

 

[CravinR1]

I just don’t think it’s a good idea to try to series like this. Batteries in series should be identical and at the same state of charge. If not then things will get out of balance and the separate batteries will get charged and discharged at different rates and eventually one will fail.

Per Currentconnected the 100ah and 206ah are identical except for capacity.
https://www.currentconnected.com/product/sok click specificiations.

All charging and discharging performance is the same. I didn't say it was a good idea but in theory 2x100ah in parallel should perform identically to a 200ah 12v battery which is basically the same as a 206ah 12v battery

And 2x100ah 12v wired in series will charge the same as 1x 206ah 12v per the spec sheet