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Parallel or Series
#1
I have 48 Nissan Leafs modules.
For cell balancing, no BMS as yet, the question is would it best to have 6 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
Radian 8048A/GSLC, FlexNet DC, Mate 3s, HUB 10.3, FM80 (2), Hanwha QCELLS 320 (24), TechLuck SHHWC (3/24), Leaf Modules (98), Hyper Engineering Sure Start
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#2
(07-08-2019, 02:41 PM)gpearce52 Wrote: I have 48 Nissan Leafs modules.
For cell balancing, no BMS as yet, the question is would it best to have 6 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

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 8s you are back to a 6p8s anyway.

Sean likes this post
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



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#3
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.
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#4
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
Still learning English. Learning Li ion and solar technology.

1400 cells in packs Exclamation above 2500mah and 90%soh.
~400 cells between 1800-2500 and above 90%soh(sell?)
600 cells between 2200 - 3000mah, 80-90%soh (sell?)
2600 waiting for testing.
approx: 500 cells not safe for use: dead, heaters, to high ir or sd

Time is our enemy, must work to, the sun is our friend, must relax to.
With best regards
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#5
(07-10-2019, 01:12 PM)100kwh-hunter Wrote: 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

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
If 18 X 650 = 2200+mAh then we have power! 
May all your Cells have an IR of 75mΩ or less Smile
Last count as of 6/10/2019
Total Number of Cells                          5940
Cells  >80% of Capacity                      4334
Cells <80% of Capacity                       1605
Cells ≥2200mAh & ≥ 80% & ≤75mΩ    2800 +236
For Info Google Drive
Not your average Wolf       
            Cool



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#6
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.
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#7
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 a extra dimension.

@offgridinthecity, interesting data!

https://www.aliexpress.com/item/32883863...4c4dCY1Fol

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
Still learning English. Learning Li ion and solar technology.

1400 cells in packs Exclamation above 2500mah and 90%soh.
~400 cells between 1800-2500 and above 90%soh(sell?)
600 cells between 2200 - 3000mah, 80-90%soh (sell?)
2600 waiting for testing.
approx: 500 cells not safe for use: dead, heaters, to high ir or sd

Time is our enemy, must work to, the sun is our friend, must relax to.
With best regards
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