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Building My First Pack
#1
I have acquired around 425 x 1865s that I plan to use for off-grid storage. I expect to get around 400 good ranging from 1700-2700mah after testing, which should be complete in another week or two. Hoping to get some opinions/suggestions on the best way to utilize these with my inverter and sorting them into packs based on capacity. The inverter is a 12v 1000w pure sine, BUT I would certainly consider a 24v inverter in the future given the voltage range of the 6s scenarios, but for now I am confined to a 12v setup. The trays I bought to hold the cells are 4x5, which is kinda throwing me off a bit as far making a few 3s packs-maybe I could just cut off or leave one row empty?



Thanks for any help/suggestions.
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#2
Trying to make 12V out of Li-Ion is very difficult. Try to go 4s if possible if the inverter/charger can handle the slightly higher top voltage.

For the holders, you could get some singles and then just clip them on to get a better arrangement.
However, for such a small setup, I would suggest using the holders to make all parallel packs, and then serial connect the packs. Don't try to make the 4x5 a 4s5p configuration.

If you insist on 3s, or the inverter/charger can't handle the top voltage limits, then just use the singles to make them fit. Make it 4x6 holders, which will be 3s8p (2 rows of 4 connected in parallel). Or you could get some of the 2 cell holders and go 5x6, which would be 3s10p (again, 2 rows parallel, but 5 in each row this time)
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#3
Renogy inverter spec sheet states over voltage shutdown is 15.5v. Data sheet also states low-voltage alarm is 11.0v but really activates at 12.1v based on what I am observing. Hard to put any load on this thing w/o it shutting down too early. I really need to find better products. Make do for now, I suppose.

Doesn't look like this inverter is a fit for 4S. Undercharging to 3.8 would defeat the purpose with this inverter it seems.
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#4
Been down this road myself...   suggest you scrap the 12v plans for Lithium-ion.  Neither 3s or 4s will work more than 50% due to incompatible voltage/DOD ranges - very unsatisfactory all around!    The bright spot with 18650/lithium-ion is that you can go 7s / 24v or even 14s / 48v and it works perfectly with most equipment.  

if you insist on 12v, then suggest LifePo4 cells and do 4s - this is very compatible with 12v 'stuff'.
Some LifePo4 cell examples....
-  https://batteryhookup.com/products/20-k2...teries-new
https://www.batteryclearinghouse.com/pro...-emc-packs
and of course there are brick/pouch LifePo4 as well Smile
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#5
(10-04-2020, 09:00 PM)OffGridInTheCity Wrote: Been down this road myself...   suggest you scrap the 12v plans for Lithium-ion.  Neither 3s or 4s will work more than 50% due to incompatible voltage/DOD ranges - very unsatisfactory all around!    The bright spot with 18650/lithium-ion is that you can go 7s / 24v or even 14s / 48v and it works perfectly with most equipment.  

if you insist on 12v, then suggest LifePo4 cells and do 4s - this is very compatible with 12v 'stuff'.
Some LifePo4 cell examples....
-  https://batteryhookup.com/products/20-k2...teries-new
https://www.batteryclearinghouse.com/pro...-emc-packs
and of course there are brick/pouch LifePo4 as well Smile


Did you mean 6s (25.2) or 7s (29.2) for 24v inverter? I was more thinking at least 2 separate 12v packs with these cells so I could go series and a 24v inverter in near future. I ordered a few 6s BMS boards to play around with.

EDIT: NVM I see Over Voltage is around 30v for 24v inverters.
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#6
7s (25.2-25.9) nominal works much better than 6s (21.6-22.2) nominal

later floyd
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