Can I connect 2x 12v in series and then parallel 1x 24v battery ??

[golfreak12]

I finally went 24v and it's something I should have done from the beginning.
So I have 2x 12v Valence 138ah in series. No way to expand this unless I can find 2 more of these and I really don't want to.
Now If I buy one 24v 140ah battery and hook them up in parallel, will they work well together ?
Seems like in theory they would but what do the experts in here thinks ?

 

[MurphyGuy]

Consult the battery's manual to see if putting them in series is allowed.

 

[golfreak12]

Consult the battery's manual to see if putting them in series is allowed.

My 2 12v are already in series.
If I get 24v battery I would connect these in parallel.
The 2x 12v are around 130ah in capacity, the 24v I would purchase has 140ah capacity.

 

[MurphyGuy]

The capacity difference is only a minor issue that can generally be ignored because its such a small difference.

Manufacturers of these cheap battery products use different types of BMS's so you'd have to ask them. Either that or just do it somewhere safe and see how it works out..

 

[The Good Package]

Yes, you can connect the existing 24v (2 x 12v) and a new 24v battery in parallel, but I highly recommend using high amp bus bars instead of direct terminal linking and make sure both are at same SOC / voltage when connecting in parallel unless you like lightning. Make sure the conductor lengths to the bus bars are (close to) the same to prevent uneven current draw. I also wouldn't drain an old / new parallel set below 25-30% SOC and I wouldn't charge past 90-95% SOC.

EDIT: I'm assuming these are lifepo4 chemistry. If lead acid, then don't drain beyond safe levels.

 

[golfreak12]

Yes, you can connect the existing 24v (2 x 12v) and a new 24v battery in parallel, but I highly recommend using high amp bus bars instead of direct terminal linking and make sure both are at same SOC / voltage when connecting in parallel unless you like lightning. Make sure the conductor lengths to the bus bars are (close to) the same to prevent uneven current draw. I also wouldn't drain an old / new parallel set below 25-30% SOC and I wouldn't charge past 90-95% SOC.

EDIT: I'm assuming these are lifepo4 chemistry. If lead acid, then don't drain beyond safe levels.

Thanks.
I've look through YT and haven't seen a video of anyone who has done one.
My eventual plan is to have 2 of these 24v 140ah Lifepo4 but I'm getting just 1 now.
Will do a brief test but a bit scare to leave this running long term.

 

[The Good Package]

Thanks.
I've look through YT and haven't seen a video of anyone who has done one.
My eventual plan is to have 2 of these 24v 140ah Lifepo4 but I'm getting just 1 now.
Will do a brief test but a bit scare to leave this running long term.

I've paralleled batteries that are years apart in age, 16s with 15s configs, different amp hours, etc. As long as chemistry is the same, you aren't mixing different model / age batteries in *series*, you aren't over charging / discharging the array, and resistance is managed properly, you're fine.

 

[JWLV]

It should be no problem. I also started with 12v and moved on to 24v. Now looking back, I probably should have started with 48v in the first place.