Parallel or Series

I have 48 Nissan Leafs modules.
For cell balancing, no BMS as yet, the question is would it best to have6 modules stacked in parallel, then 8 in series or 8 modules stacked in series then 6 in parallel. Both would be charged to 64v,

Thanks

gpearce52 said:

I have 48 Nissan Leafs modules.
For cell balancing, no BMS as yet, the question is would it best to have6 modules stacked in parallel, then 8 in series or 8 modules stacked in series then 6 in parallel. Both would be charged to 64v,

Thanks

Click to expand...

Voltage wise it would be the same result as you know.

If you do 6p8s The BMS solution would be the easiest. 1 8s BMS
If you go pure 8s you would need to get 1 8s BMS for each string so in essence 6 BMSs
If you tie the junctions together in the 8syou are back to a 6p8s anyway.

Check out this post from Stephen Kunkel and the link he posted about parallel battery packs. A single BMS is easier and more secure. I'm using parallel packs with parallel BMS'es, but each BMS can disconnect its pack from the main bus - a setup which slightly differs from your second drawing.

Little off topic, sorry, but i would like to know.

@ Wolf, how do you do those drawings.
Probably a stupid question, but the only stupid question is the one that you never asked.
I am also not much of a computer person.
I stopped after c basic ...

Thanks

100kwh-hunter said:

Little off topic, sorry, but i would like to know.

@ Wolf, how do you do those drawings.
Probably a stupid question, but the only stupid question is the one that you never asked.
I am also not much of a computer person.
I stopped after c basic ...

Thanks

Click to expand...

Basic MS progie called "Paint" and a little bit of patience.
There are others but for a quick representation of a concept it works well




Wolf

One of the interesting things about Batrium is that it is a 'single BMS' that monitors / balances either configuration. You can put 1 longmon per cell (as in bottom picture) or 1 longmon per parallized cell (upper picture)... BUT as demonstrated by @HBPowerwall you can put multiple longmons on a single cell... and choose to achieve a wide range of balanace amps per cell regardless of how you build the battery.

The main driver for me (these days - after a year of operation) is how to detect and replace individual 'cells' (packs) as the battery weakens over time. So its a matter of 1) detection and 2) physical 'ease' to unhook/replace/rehook individual cells my guiding design.

Thanks Wolf, I tried but it's not my thingy, I will keep on using paper and pencil.
Not patient enough, I am a person that gives computer aggression an extra dimension.

@offgridinthecity, interesting data!

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https://www.aliexpress.com/item/32883863452.html?spm=a2g0s.9042311.0.0.f5524c4dCY1Fol

I bought this one, to monitor every year the deterioration of the pack(s)
I am planning(for now) to take out next year, every year a whole pack(14 of them) and test them