Experts! I am working on a hybrid vehicle design and I have need to build a battery pack with a 14s configuration, multiple (4) 14s packs in parallel. Now I'm confused as to which configuration suits best. Please refer to the diagrams.

1. Config 1
I will need 4x BMS chargers for this. Benefit is that I can monitor each and every single cell (Although I am still trying to figure out how to connect those 4 BMS chargers to this configuration.

2. Config 2
I'll just need one BMS charger with each terminal charging a pack of 4 batteries connected in parallel. I save on BMS chargers, the connection is simple but I won't be able to manage imbalances in any one of the parallel packs.

Please share your inputs as to which one is better suited so that I can finalise the design accordingly. Thanks a ton in advance!

Regards,
Deepak

 

By battery do you mean cell??? are these 18650 cells ???

In your second diagram they all appear to be connected in series which will give 200 volts ..

This is a 4p 14s battery you are making ? with 18650 cells this is about 50V delivering 12A over 1 hr discharge , it's usual to have one charge controller for such a pack , no need to monitor each cell . this is the size of battery for an ebike many youtube videos on this,

Usual wiring is to connect 4 cells in parallel .... 14 times .. put these 14 3.6v blocks in series

 

If 4p = 1 pack, won't you need 14 BMS modules to ensure charge balance between the packs?

 

Ok, my bad for not being clear with the diagram. I've update the diagrams with little more clarity (hopefully enough). Apologies for the low quality of the diagrams.

- These are 18650 LiIon cells of 2600 mAh capacity, giving an overall capacity of 10.4Ah in my configuration
- Red line is for parallel connection and blue line is for series connection.

In Config 1, A-A is one 14s pack. So is B-B, C-C and D-D. Each of these 14s packs are connected in parallel. In this case as I understand, I'll need 4 BMS chargers charging each of the 14s packs. Total capacity is 58.8V (peak)/51.8V (nominal)/ 10.4Ah


In Config 2, A1-B1-C1-D1 is a 4p parallel pack (like in battery banks) and so are An-Bn-Bc-Dn. Each of these parallel packs are arranged in series connection, giving me the same capacity of 58.8V (peak)/51.8V (nominal)/ 10.4Ah. But here as I understand, I'll need only BMS charger, at the cost of not being able to monitor each cell in the 4p parallel packs (the whole 4p pack is seen a one cell by the BMS charger terminal connected to that 4p pack).

Hope this makes better sense now? I'm quite tempted to use config 2, but just need some more thoughts on the two configs before I decide.

Regards,
Deepak

 

If 4p = 1 pack, won't you need 14 BMS modules to ensure charge balance between the pack?

Since 4 cells are in parallel, voltage seen by the BMS terminal will be as good as 1 cell (averaged across 4 cells). With 14 such 4p packs, i'll just need one BMS capable of charging a 14s pack.

This is my limited understanding till date of how the BMS charges and the configuration used for the same.

 

Very strange wiring diagram , i still don't think the second one looks correct ...

But yes ... you have 14 , 4p packs , just wire these packs in series and use a 14s BMS , this is the only sensible arrangement .

 

Sorry for the bad diagrams. Little short on time to make a better one. Thanks for your inputs. I'll use the 4p parallel packs (Config 2) to built the whole config.