Server rack batteries (48v) vs series sets 12v (48v)

[SCmountainman]

Looking for insight on expanding my battery bank after Christmas. I have (2)-5kwh 48v ARK lithium pre built server rack style lifepo4 batteries already. I’m wanting to expand my battery bank to 30kwh.

I’m thinking of using (2) parallel sets of (4) chins/zooms/lossigy etc. 12v 200ah lifepo4 packs in series instead of going with more server rack style batteries. This would give me 20kwh more capacity for +/- $5200 not including disconnects, fuses, cabling, etc. They are readily available and ship free.
Pros-cheaper, arrive faster, seem to have decent build quality. I have a 12v system as well, so if something happens to a series set, I can break down and keep good batteries for my 12v system.
Cons-I have to add additional fusing/breakers, extra wire cost, shunt to monitor, could lose a bms and lose a series set dropping my bank down in capacity if something went wrong. Extra components are extra points of potential failure.

VS. EG4 or similar batteries, which I would need (4) of the 5kwh pack which would be +/- $7400 with shipping. Not including cabling and accessories. They also go in and out of stock rapidly and I don’t want to pre order.
Pros-fast wiring and integration into my existing system. LCD displays. “Gold standard” of affordable pre built batteries.
Cons-way more costly, go out of stock often, dealing with freight shipping so I would have to drive to a terminal for pickup which is 45 miles away.

Just looking to get more autonomy for rainy days. I can run 2 days on my current setup with no sun. Trying to get at least 5 days. Want to reduce my generator usage during extended rain/snow/cloud events.

Anything I’m missing? Anything I’ve overlooked? Please advise. Thanks!

 

[Samsonite801]

I would always typically go for best serviceability, like a pack or setup that has screws to easily disassemble it, readily available common cells and common BMS type, I would rather not have to use a Dremel tool to cut open a pack in the event troubleshooting is required (unless it has a 10-year warranty or something, where the company can just replace the whole module for me upon failure).

To me, that is the biggest factor on buying a blackbox battery vs a DIY battery is the warranty duration. On DIY, the component-level may have warranties but the whole assembly is serviced/warrantied by you .

But it seems the server rack style 4U (or whatever they are), like GYLL/EG4 might have screws and be able to be taken apart, not sure how easy replacement cells are to come by or BMS or anything. Those do have a 5-year warranty.

DIY is still way cheaper to build your own, and that's the way I personally went.

The other factor one might consider is if they want to have inverter-to-BMS communication to get SoC data, if you're fine using a shunt or clamp solution to get SoC, then I guess it doesn't matter what kind of BMS you use. Like for example, MPP inverters can work with Pylontech or Seplos BMS (amongst others), or GYLL/EG4 offer native BMS communication with Growatt inverters, etc...

 

[Don B. Cilly]

Want to reduce my generator usage during extended rain/snow/cloud events.

You got the Solstice Blues? So do we all, I guess. :·)
But, is it worth it (to spend all that money, set it all up, maintain it, monitor it...)
A lot less money/effort will get you a better generator (and charger) with remote/automatic start, petrol/propane for... pretty much ever, a sound-proof box with ventilation, a couple windmills to take the edge off... work it out, if it's worth it, it is. If it isn't - really...
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