PARALLEL THEN SERIES VS SERIES THEN PARALLEL BATTERY

Hi,

New here, I want to ask your expertise regarding lithium-ion batteries.

Lets say I want to build a 12V battery or a 3S battery with 2x the capacity of single cell.

Example: battery spec = 3.6V cell with 2.1AH capacity.
Target: 12V 4.2AH capacity

To get a 12v we can do a configuration below:

1.) 3 batteries in Series to get 12v 2.1AH and then parallel another pack of 12V series to get the 4.2AH.
2.) 2 batteries in parallel to get 3.6V 4.2AH capacity then connect 2 more set of these in series to get 12v 4.2AH.

which is the best configuration and why?

Thanks!

There's a number of threads that go thru the info you're after in some detail. Some of them are in the list linked below. Not everything there is relevant, but you can see from the thread titles which ones probably are.
https://endless-sphere.com/forums/search.php?keywords=parallel+series&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

Will you be using a BMS?

Option 1 & 2 is the same... both will give you 3S2P.

In general, add battery in series will give you more voltage, adding battery in parallel will give you capacity.
This is what most of the battery pack are made off..

Unless you're going for very big battery pack that need to spit the battery separately.

markaugust30 said:

Hi,

New here, I want to ask your expertise regarding lithium-ion batteries.

Lets say I want to build a 12V battery or a 3S battery with 2x the capacity of single cell.

Example: battery spec = 3.6V cell with 2.1AH capacity.
Target: 12V 4.2AH capacity

To get a 12v we can do a configuration below:

1.) 3 batteries in Series to get 12v 2.1AH and then parallel another pack of 12V series to get the 4.2AH.
2.) 2 batteries in parallel to get 3.6V 4.2AH capacity then connect 2 more set of these in series to get 12v 4.2AH.

which is the best configuration and why?

Thanks!

Click to expand...

Pretty much, you can do whatever you want if a bms is not involved. So for no bms, it can be less trouble to connect in series first, then make parallel connections. Particularly, this is true if you are starting out with factory assembled 1s strings of cells in the first place. ( Roomba packs, drill packs, RC lipo packs, laptop packs, etc)

But if you are making all connections yourself, like spot welding them, parallel first makes more sense. Why? because instead of checking the voltage of 2 cells as you would in series first, you need only monitor the voltage of one set of paired cells. And, it is bms ready, if you choose to bms later, or right now.


But if you are going really big, it is very possible to make two packs with bms, and still parallel them later. They need not be the same size, just the same cell count. Example, 5 ah 13s can parallel with 10 ah 13s no problem. But in the example, you would still need to separate the packs to charge each one separate. There is a way to connect two bms permantently btw. So in a way, everything is possible.