40 new Grade A 100AH 3.2v matched prismatic cells, building a 24v 500AH setup.

plaidcabin

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May 3, 2021
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40 cells

8 cells per battery in 24v series

5 batteries in parallel setup for 500AH.

New to solar, and never built a battery before, so bear with me but I think I've almost got this figured out. I plan to test each cell and carefully assemble each battery, using solder for BMS leads if needed, and Hot Glue for wire management - make it look real nice just like I would with a PC build. Polyimide tape to hold them together, and I will build enclosures for them as well. By the fifth one I should be a pro!

I plan to use 5x Daly 100a 8S 24v BMS (one per battery). These seem to be the practical choice for a beginner. This way if one battery is weak it can be easily removed and repaired or replaced, at the cost of shortening the life of any replacement cells once they are balanced into the system. Not really a major concern at this point.

My real concern is this: Will these BMS be damaged if the inverter draws more than 100A from the battery bank? I am using a Giandel 4000w (8000w peak) 24v inverter, it can pull quite a lot of amperage. Will the load be pulled through each bms in this configuration, or is it balanced between them?

edit: It's possible to cause damage when setting up this way, but only if configured incorrectly. I will be using 600A rated bus bars to put the 5 batteries in parallel, and a diagonal connection for the inverter and MPPTs. Following this guide I should be safe!

https://diysolarforum.com/attachments/screen-shot-2021-04-05-at-1-29-59-pm-png.43908/



Thanks for all the help, this website is such an incredible resource!


For those curious, I am planning to run 2 strings of 3 335w mono Canadian Solar panels to 2 Epever Tracer BN 40A MPPT's with this setup for charging. Solar cabin, no grid tie!
 
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Supervstech

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parallel connections split the total amperage load across banks.

so, 5 banks of 100AMPS totals to 500A of potential. Assuming your bussbars are connected well, and sized for the load, there shouldn’t be an issue.
post pics of your build!
 

plaidcabin

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Thank you, I certainly will post updates as it progresses. Right now I am just finalizing all of my parts and trying to figure out the wiring and layout.
I can't get all of my lumber until July, and the system won't be installed in it's permanent home until the cabin is built, in the mean time I am just acquiring components and intend to do plenty of testing once I have enough put together.

Should the inverters connections to the bus bars be at the same ends as the MPPT'S, or the opposite ends, to maintain the diagonal approach to balancing the load?
 

Northernchateau

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Did you already purchase the batteries?
If not I might suggest you look at the 200 ah, 280 ah or 310 ah.
You would need less of them and as far as I see the cost per amp hour is less.
 

plaidcabin

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They are difficult to get at this time, I would have preferred it but have to work with what is available. I got a great price on the 100AH cells.
 
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