24v 280ah battery config help

Famtraveler24

Solar Enthusiast
Joined
Jul 22, 2020
Messages
130
Hi all. From 24 280ah cells, I intend to build 3 batteries of 8 cells each and each with its own Overkill Solar 8s BMS.

Query: should I arrange the 8 in series and then connect the 3 batteries in parallel? Or something different?

Ultimate goal is to have 24v 840ah bank.

Thx.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Joined
Oct 29, 2019
Messages
5,792
Location
Rural NE Ontario Canada
KISS is always the best approach IMO.
3x 24V/280 in parallel will allow for sharing of both load & charge.
They should all be Top Balanced and at the same voltage when put into parallel.
Each Battery Pack should have its own fuse.
Wire runs from pack to busbar should be same length for ALL packs, both (-)&(+) as well. Try to keep the wires close together to prevent RFI/EMI from the DC.
 

Famtraveler24

Solar Enthusiast
Joined
Jul 22, 2020
Messages
130
KISS is always the best approach IMO.
3x 24V/280 in parallel will allow for sharing of both load & charge.
They should all be Top Balanced and at the same voltage when put into parallel.
Each Battery Pack should have its own fuse.
Wire runs from pack to busbar should be same length for ALL packs, both (-)&(+) as well. Try to keep the wires close together to prevent RFI/EMI from the DC.
So, 4p6s or 8s3p? Which is better? Will suggest wiring in parallel first, but I'm not sure I appreciate the distinction. Thx
 

Pyrofx

Flux capacitor builder
Joined
Jul 27, 2020
Messages
535
Location
Oatman Az
It can eat up 2/0 cable. My 16s 6p ended up using about 70 feet of welding cable.
Buy the Chinese lug crimped. They are pretty reasonable and make great ends.
 

DThames

Photon Sorcerer
Joined
Nov 22, 2019
Messages
1,780
Hi all. From 24 280ah cells, I intend to build 3 batteries of 8 cells each and each with its own Overkill Solar 8s BMS.

Query: should I arrange the 8 in series and then connect the 3 batteries in parallel? Or something different?

Ultimate goal is to have 24v 840ah bank.

Thx.
For $6 you can purchase the phone app for that BMS and set the BMS voltages the way you want to.....really great functionality. You can give each BMS a name so you can tell them apart on the app.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Joined
Oct 29, 2019
Messages
5,792
Location
Rural NE Ontario Canada
8S3P - Paralleling cells in a pack can be done BUT only with properly Matched & Batched cells and with great care, these are not small EV NMC cells, which are perfectly Matched Batched and Binned to be identical.

Straight simple 8S for 24V = KISS.
BTW: I use 4/0 Royal Excelene Welding Wire & Selterm Tinned Lugs. One area to never cheap out on is the grade of the Heavy Wire that carries the loads. Like Fuses & Breakers some things are best NOT to cheap out on. See the links in my Signature for more details & info. The about my system page will be updated again 1st week of April when I complete finalizing my LFP battery with the last 24V/280 going into place and the two 175AH's are converted to one 350AH pack. Yes I am paralleling those cells as they are used EV LFP cells and there is too much amperage difference between 175 & 280 which creates certain issues.
 
Top