Different capacity batteries in parallel?

[andyP]

Is it ok to put a 240ah battery in parallel with 4 120ah batteries?

All are LiFePO4, home built with 4x3.2v cells.

Any long term considerations?

I'm thinking of adding 4x240ah cells to my 4s4p (or is it 4p4s?) 480ah batt. (I have 4 separate 120ah batts connected in parallel)

 

[chrisski]

Some have done it and claim its only an issue at the bottom 20% when the smaller banks start to feed off the larger banks; however, for me, I would really look at either:

1) Ordering 8 X 120 ah cells and build two more batteries
2) Ordering 4 X 240 ah batteries and configure the other 16 X 120 ah cells to be 2P4S

Mismatched is supposed to be OK, especially the closer the AH rating is. You’d certainly be in the minority the bigger the mismatch in AH of batteries you hae.

For me I’ve never been the first on my block to do anything when it comes to putting down money, but even though mismatched cells is not blazing new trails, its getting off the beaten path. SOmething I’d feel more comfortable with after using lithiums a lot longer than the three months I have been.

 

[MrM1]

Yes it can be done. It would b better if the capacities were more closely matched. But it is possible.

Parallel pack extreme part 1

Parallel pack extreme part 2

 

[Levo]

I am considering 2 or 3 100Ah batteries in parallel. I'd rather spend $1000 than $1500. I think 2 will suffice. However, I may decide after one season I need 300Ah in total. From what I have read here, adding a third identical battery later should not be a problem, right?

 

[chrisski]

I am considering 2 or 3 100Ah batteries in parallel. I'd rather spend $1000 than $1500. I think 2 will suffice. However, I may decide after one season I need 300Ah in total. From what I have read here, adding a third identical battery later should not be a problem, right?

If its a lithium battery No problem. If its a lithium battery, capacity need not completely match either.

 

[newbostonconst]

I have 280's in parallel with 55, 55, 55, 55, and 50's all in a 20 cell series and working great.....

 

[RV10flyer]

I have 4S 12V 240 aH LFE with Daly 250A BMS and 3P4S 12V 300 aH LFE with Daly 250A BMS, along with lead acid switched on occasionally for recharging. It works fine for me with proper wiring and current protection.

 

[chrisski]

I have 280's in parallel with 55, 55, 55, 55, and 50's all in a 20 cell series and working great.....

20 cells is different. Is that a 60 volt battery?

 

[Levo]

If its a lithium battery No problem. If its a lithium battery, capacity need not completely match either.

Yes indeed LiFePO4. Thanks for your answer.

 

[RV10flyer]

A good dc clamp-on amp meter will show you where those little electrons are going.

 

[HARG Hunter]

I can't speak for LifeP04, but my AGM battery bank is a Frankenstein of sorts (photo attached).
I've got (1) 100ah and (3) 35ah batteries in series. It struggled at first but I initially had the connections to the charger and inverter coming from the same battery. After feedback on this forum, I rewired the batteries with heavier gauge cable and made the connections to inverter and charger from different ends of the bank. Made all the difference in the world.

Not ideal, but if you are in the same position I was (Didn't have the budget to correct my purchasing mistake) it can work until you are able to balance things properly.

 

[darogue]

Some have done it and claim its only an issue at the bottom 20% when the smaller banks start to feed off the larger banks; however, for me, I would really look at either:

1) Ordering 8 X 120 ah cells and build two more batteries
2) Ordering 4 X 240 ah batteries and configure the other 16 X 120 ah cells to be 2P4S

Mismatched is supposed to be OK, especially the closer the AH rating is. You’d certainly be in the minority the bigger the mismatch in AH of batteries you hae.

For me I’ve never been the first on my block to do anything when it comes to putting down money, but even though mismatched cells is not blazing new trails, its getting off the beaten path. SOmething I’d feel more comfortable with after using lithiums a lot longer than the three months I have been.

Can I run 4 100 ah AGMs in parallel and then hook them to 2 310 ah AGMs. 1200 w -60 amp controller- 3000 inverter?

 

[chrisski]

For lead acid batteries, I would say never a good idea to mix and match.