diy solar

diy solar

Shelves for 3x 280Ah 48v LiFePO4 Banks?

Sounds like a plan. As long as it fits. I have two sets of 8x8 for 32 280ah Lishen cells in a 48" box, with the cells upright, and it JUST fits. Plenty of room from the terminals to the top of the box, but just enough to squeeze in the insulation paper, and heating pads along the sides.
I didn't want to risk going with the 24" box. It would be nice and narrow, but the pack itself without insulation between cells is 24." With everything bound and insulation installed, I might need a maul to get them to fit. (If it doesn't fit, force it...if it breaks it needed replacing anyway. ?) The 30" box will give a bit of room, although I wonder if 36" would be better. I think the space available will determine what I do regarding compression.
 
I have a bunker with 6" concrete walls and ceiling in one corner of basement. Bunker is about 60" wide. I was thinking to pour a 60"concrete shelf and set batteries on that. A couple bags of concrete and some rebar shouldn't cost so much.
I would love more info on that bunker since I have no outbuildings would you be willing to share details
 
I would love more info on that bunker since I have no outbuildings would you be willing to share details
Wife and I built house from scratch. We had concrete contractor put in a 6'x16' room with concrete ceiling in one corner of the basement. Sorry that this probably doesn't help you very much.
 
Wife and I built house from scratch. We had concrete contractor put in a 6'x16' room with concrete ceiling in one corner of the basement. Sorry that this probably doesn't help you very much.
No, but it is very cool nonetheless. it is the ceiling that is the weak point I have a concrete slab, and could easily build block walls to the needed height, but how to cap it? Hmmmmm
 
Wife and I built house from scratch. We had concrete contractor put in a 6'x16' room with concrete ceiling in one corner of the basement. Sorry that this probably doesn't help you very much.
Man I would love one of those. I would add AR500 steel in the walls, or sand, to make it a real safe room. But it would need 2 exits.( I think I listen to too many SHTF / end times audio books). ?
 
No, but it is very cool nonetheless. it is the ceiling that is the weak point I have a concrete slab, and could easily build block walls to the needed height, but how to cap it? Hmmmmm
Contractor used corregated steel with 8" of concrete poured right on top. The corregated can take a lot of weight.
I would use caution when putting weight on an existing slab. My bunker used good size footings
Man I would love one of those. I would add AR500 steel in the walls, or sand, to make it a real safe room. But it would need 2 exits.( I think I listen to too many SHTF / end times audio books). ?
Yes, steel door is about 300 pounds :)
 
Very delayed update!

The build is currently as follows:
  • Went with the 30" boxes for my setup.
    • Was short on neoprene to line the boxes and couldn't find any replacements for a reasonable cost, but the areas that the cells may touch has been covered.
    • Drilled holes for power in, power out, switch, and button for priming the inverter.
    • I decided to space out the cells, as I have a few that are bulging slightly so they won't sit flush. (It looks like a cylinder vertically under the cell's tapped contacts.) Keeping even space was difficult due to them sliding easily on the starboard. *doh*
  • Built a shelf out of unistrut and had to wait for 90° elbows as there was no stock on the island. (1st delay)
    • Quick coat of paint to slow any potential corrosion.
    • Ordered 6 rubber feet for the unistrut so that it didn't dig into or slip on the concrete. (The unistrut essentially sits on a metal plate that's surrounded by rubber.)
  • Got some 1/4" starboard from a local supplier and cut it to fit under the cells in the box, and as a shelf liner so the boxes weren't sitting directly on the steel.
  • Built a small shelf out of wood to hold the BMS, balancer, fuse, and cell connection junction. (This will allow me to change the BMS and/or balancer without messing around with the cell's terminals.)
  • Cut and crimped cables to go from the cells to the junctions.
  • Put insulation between cells. (18650 Battery Pack Insulator Gasket) I might double up on the insulation later, but I'll see how I feel about it later.
  • Ordered 3 longer bus bars as the stock ones won't reach from short-side to short-side of cells.
  • Made up 1/0 cables. (Used to connect the cells to the BMS, fuse, switch, and bus bar.) I need an additional 53.5" for the top bank's positive line. I can only order 10' of cable, so I have more than I need on it's way...until it gets here, I can only run 2 banks.
  • Made up 4/0 cables. (Used to connect bus bars, shunt, and inverter.)
  • Ran conduit for the PV and AC lines.
  • Installed a 200A manual transfer switch. (I over-sized on it so that I wouldn't have to mess with it again in the future if I needed to up-size my grid feed.)
  • Installed DC breaker box to protect equipment and act as a cutoff switch near the main house supply.
I ran a quick charge and low draw test for 3 hours on the 8th and all was happy. Yesterday at 8:30am I turned everything on and threw the transfer switch for a long use test. I had 2x 12k btu split unit AC's running, the dishwasher, TV, NAS, computer, fans in every room, the 5kW water heater for ~1hour, and charged the car with a level 1 charger for ~4 hours. The batteries topped off and the BMS threw a fit due to a runaway cell. It threw the relay which caused all charging power to go solely to the remaining unit, which threw one cell into runaway. The process "rinsed and repeated" twice while I was checking to see wtf was going on. I ran inside and turned on extra load and turned on the active balancers for the two batteries. The top balance was finalized a little later, and I dropped the charge voltage to 55.6v (3.475v/cell) and set the float to 54.6v (3.41v/cell) to give the balancer time to balance before it shuts off at 3.4v. I'm very tempted to get the JK BMS with integrated active balancer that Andy from the Off-Grid-Garage has reviewed and is currently using in one of his batteries. Before doing so, I'll see how things go with what I've got after tweaking a bit.

Looking at the capacity draw and charge, I was able to pull 30kW from the array according to the Victron shunt. The GroWatt inverter reported 27.2kW pulled from the banks, which works out to about 90% efficiency...not bad for a top of 60% capacity for the 12kW unit. I estimated that I'd have just shy of 27kW available without accounting for inverter losses. To say I'm pleasantly surprised is an understatement! I'm excited to get the last bank up and running, but now my eye is on finding space to have more panels. ?

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I'll post a pic of the current situation when I can. I'm not finished with tidying the wiring inside the battery banks, and I'm contemplating covering all bus bars and contacts with kapton tape for an extra layer of protection from accidental contact.

Let me know if you have any questions or suggestions!
 
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