280Ah Battery, Just Beginning

Getting ready to start a 280AH 48vdc battery build. Batteries have been ordered from Docan, JK-B2A24S20P BMS from Hankzor. Nothing else has been ordered/purchased. On to the list, what was forgotten, what is not needed, alternatives? This will be connected to an AC-Coupled (to 4kw Enphade M215 system) 5-8kw inverter yet to selected.

4 position switch (1 On, 1&2 On, 2 On, All Off) either 1 or 2 will be pre charge circuit.
2/0 Cable & Lugs
250A DC breaker
350A DC T-fuse and holder
100w 10 ohm resister for pre charge circuit
Victron Shunt
1/4x20 all thread
1/2” poly board

Battery Box metal, 24”w x 15”d x 12”h
Thru Panel Terminal Connectors
Terminal Covers
1/4” Hardiboard/Durarock to line box
Peel & stick neoprene/rubber lining to cover cement board
Drok Volt/Amp meter?

I don't know how well the peel & stick will work directly on the backer board. I'm starting a project to create a lid for my battery bank using 1/4" Hardie Backer Board. I'm going to paint it first, hoping that peel & stick vinyl will stay where I put in.

Make sure that your components are rated for a 48 volt system. There are a lot of components out there that are rated up to 48 volts, but not beyond that.

What version are your M215s? The reason I am asking is because if they are not UL1741 SA compliant your AC coupling may be constrained. Also the capacity of your future Hybrid grid forming inverter needs to be able to accomodate the GT micro total output or you might have to split off some of the micros from that hybrid. These are just planning considerations and not an attempt to be critical. I have a working AC coupled system with micros. Here to help.

Good idea on sealing the backer board, had not considered that. Yes, a lot of the components I have looked at are only rated to 32 volts, really have to dig finding 60vdc.

@Ampster please be critical, this is going in my attached garage so I want to be cautious and over spec every thing.

My M215’s are from 2012 so they are binary, on or off. I have 20 M215’s paired with CS 250w panels. On a good day I can get about 3.8kw peak output. The highest monthly output was 849 KWh and 129 KWh being the lowest. Daily averages over 12 months are 30 KWh consumed and 23 KWh generated. Planning for 5-8 kw inverter (prefer LF to handle back feed surges), TBD.

Batteries (16 LF280N) have shipped - only 30-40 days to go!

Advice/opinion on capacity testing:
1. Don’t worry about it, top balance, build battery and discharge/charge thru BMS monitoring cells.
2. Capacity test each cell prior to build.

On compression, to compress or not. My plan is to install the cells in a 4x4 arrangement Inside a 14ga welders toolbox (30Lx16Wx12H). Each group of 4 cells held in place with 1/4x20 all thread and 1/2” cutting board (poly) torqued to 4-5 ft/in. Thoughts?

I'm just building my battery. I just got one set of 16 cells top balanced. Going to reposition them into parallel, snug the fixture (just a 2x8 layout with 6 threaded rods and plywood end plates and bottom). Done. I'm not screwing around with measuring pressure but I don't want them sitting free. Just snug so the bus bars stay unstressed is fine, IMO. I'm no expert though.