diy solar

diy solar

Rethinking my battery box

SparkyJJO

(un)Certified Arc Generator
Joined
Jan 31, 2022
Messages
2,166
Location
Ohio
I have:
32x 230Ah EVE cells. Supposed to be grade A blah blah. Bought from Docan about 2 years ago. Did not get them commissioned yet.
2x JBD BMS with 300A rated contactors (yes, I know, way overkill)
2x 250A class-T fuses
2x DIHOOL 200A MCCBs rated at ICU of 25kA and ICS 20kA
2x shunts with displays
A bunch of 10mil thick Mylar/PET sheets I was going to use as separators (but second guessing myself)

I was going to put them in plywood boxes using insulated threaded rods to keep them snug (I'm not doing some super crazy compression). These boxes were going to sit on open metal shelves that are bolted to the cinder block wall in my basement.
This hasn't happened yet. The end boards are cut and drilled but nothing is actually hooked up yet. Cells are just sitting happy waiting on me (I check them occasionally and no issues yet despite sitting this long)

After a recent big thread about someone's otherwise awesome setup going up in flames, I think about risks. Now I would think I'm covered against something going wrong pretty well between the contactors, breakers, AND class T fuses. Combined the breakers and fuses gives me the ability to quench 45kA in theory, and these packs aren't going to be capable of that much. But still, maybe an enclosed metal box is better.

Was thinking of Luyuan's DIY box, modified to fit my 230Ah cells, but then I saw @Tulex box here https://diysolarforum.com/threads/first-of-two-battery-builds.66085/

Raw box looks like this
1714676158113.png

It got me thinking a bit. I can buy those boxes for about $100 each.

I don't like the cells on their sides, so I'm now thinking take that box, lay it down, put cells inside, fab up a couple plate(s) with insulators of course to hold the cells in place. Stick the BMS in the end with the breaker, fuse, and my shunt/display.

Any reason I should skip that and just go with a prebuilt box, since I have to mod something to work anyway with my 230Ah cells?
 
I went with Buyer's "Underbody" toolboxes and I will keep using various forms of truck bed and body boxes I think. They cost more, like $200-300, and they're kind of a pain to modify but that's for the reason that I like them for which is that they're made of pretty thick steel.

 
I have:
32x 230Ah EVE cells. Supposed to be grade A blah blah. Bought from Docan about 2 years ago. Did not get them commissioned yet.
2x JBD BMS with 300A rated contactors (yes, I know, way overkill)
2x 250A class-T fuses
2x DIHOOL 200A MCCBs rated at ICU of 25kA and ICS 20kA
2x shunts with displays
A bunch of 10mil thick Mylar/PET sheets I was going to use as separators (but second guessing myself)

I was going to put them in plywood boxes using insulated threaded rods to keep them snug (I'm not doing some super crazy compression). These boxes were going to sit on open metal shelves that are bolted to the cinder block wall in my basement.
This hasn't happened yet. The end boards are cut and drilled but nothing is actually hooked up yet. Cells are just sitting happy waiting on me (I check them occasionally and no issues yet despite sitting this long)

After a recent big thread about someone's otherwise awesome setup going up in flames, I think about risks. Now I would think I'm covered against something going wrong pretty well between the contactors, breakers, AND class T fuses. Combined the breakers and fuses gives me the ability to quench 45kA in theory, and these packs aren't going to be capable of that much. But still, maybe an enclosed metal box is better.

Was thinking of Luyuan's DIY box, modified to fit my 230Ah cells, but then I saw @Tulex box here https://diysolarforum.com/threads/first-of-two-battery-builds.66085/

Raw box looks like this
View attachment 212902

It got me thinking a bit. I can buy those boxes for about $100 each.

I don't like the cells on their sides, so I'm now thinking take that box, lay it down, put cells inside, fab up a couple plate(s) with insulators of course to hold the cells in place. Stick the BMS in the end with the breaker, fuse, and my shunt/display.

Any reason I should skip that and just go with a prebuilt box, since I have to mod something to work anyway with my 230Ah cells?
This is a crazy coincidence. I just convinced myself that this is the way to go for my 8S setup. I think I can fit it into a 20"x12"x10" that costs $80.

I didn't even see that thread. If I had I might already have done it.
 
I went with a 16 X 24 X 12 box to have room in front of the cells. The boxes come in a bit undersize, my 304ah cells just fit with about 1/16 of rubber foam between the cells and on the ends and a 1/8 plate to cover the hole in the bottom.
 
I only need about 17 inches for my 230Ah cells, so there would be plenty of space for my stuff in there. But that's why I'd need to fab an internal end plate of some sort to bolt in.
 
Where are you getting these boxes at that price?
They're all over ebay. Couple different brands and sellers.

I think the hardest part for me would be cutting the holes properly for the shunt display and the breaker. I don't have fancy cutting tools so they'd probably be a little rough. I can drill holes (kind of) accurately (enough) for mounting stuff otherwise.
 
I am thinking about putting everything inside a server cabinet like this after reading that post.
CHEALON 12U Wall Mount Rack for 19" Network Equipment with Locking Glass Door and Universal Wheels Network Cabinet 2 Cooling Fan Mounting Holes on Top Black Network Cabinet https://a.co/d/0AkWFEX
 
Thought about those before. What gauge are they?

I just pulled the trigger on a pair of the Vevor boxes. They're 16 gauge think, should be sturdy enough. I'm thinking a couple L brackets with a rubber coated steel plate should work as the end plate provided I can get one cut the right size.

I wish I had better fab tools and skills to cut holes but I'll make it work.
 
The boxes come with a backer plate to mount things to. I took it out to make more room for the cells. I used a piece of that for my pusher.
Can't see it in my build, but there are pusher screws on the bottom. All I did was drilled a couple rows of holes to put flange nuts in from the inside. Then put bolts in from the outside. I put the plate in the bottom, filled it with cells with some foam spacers that compress 25% at 11 psi, then snugged the screws to just push the pusher plate to close the gap. So, no real compression. I don't push my cells, so the swelling should be minimal, hoping the foam compresses enough for that. Also what doesn't show in the picture is a 1" X 2" aluminum channel that runs across the bottom of the box. This was to help stiffen the bottom of the box and raise it so it wasn't sitting on those pusher screws.
 
Thought about those before. What gauge are they?

I just pulled the trigger on a pair of the Vevor boxes. They're 16 gauge think, should be sturdy enough. I'm thinking a couple L brackets with a rubber coated steel plate should work as the end plate provided I can get one cut the right size.

I wish I had better fab tools and skills to cut holes but I'll make it work.
When they come in, can you please post some pics of the box after removing the backer plate? I want to see what I’m getting into as the base. Thanks for letting me draft behind you on this.
 
The boxes come with a backer plate to mount things to. I took it out to make more room for the cells.
Do you remember how much room you gained when you removed the backer plate? If it gives me at least a 1/4" I should be able to go with a 10" deep box for my EVE 280s
 
It looks like those are exterior not interior dimensions. I measured my EVE 230Ah cells and frankly I just wasn't comfortable with how close it looked like the 10" might be to the top. Probably would fit ok, but it was minimal cost up to get the 2" deeper box and no other downsides really.
 
Right. From what I’ve found, the Interior dimension for the 10” is 8.5”. I need just a little more to make it work.
 
Do you remember how much room you gained when you removed the backer plate? If it gives me at least a 1/4" I should be able to go with a 10" deep box for my EVE 280s
I don't. There are dimples for carriage bolts that hold it off the back a bit, but I don't remember if there was a spacer. Overall outside dimension of the box is 11-15/16.
 
When I purchased a second set of the eve 230s, I had originally intended to duplicate the single box. Then for some reason decided a portable installation was better because I could yank an Andersen connector and wheel it out in to the driveway in case of a fire. So version 2 was in a larger truck toolbox on wheels.

 
So some boxes arrived. They're a bit heavy, which is good (and bad, if I ever have to move them after assembly lol).

20240506_111035.jpg

Nice and roomy. Remember these are the 24x16x12. The steel is plenty thick and sturdy.

20240506_111244.jpg

Some interior measurements real quick, without and with the mounting plate.

20240506_111321.jpg20240506_111336.jpg

A pair of my EVE230 cells, for reference. I'm planning on lining the inside of the box that makes contact with the cells with neoprene to insulate it from shorts and give a little cushion. Box will remain flat on its back and the lid will be on top for access. I'll need to do something to keep the cells in nice neat rows. There will be separator sheets between every cell also.

20240506_112705.jpg
 
Looking at this again I'm wishing I had a good way to cut steel plates nice and square. Would make life much easier if I had that ability. Was thinking maybe I could use some L brackets and something like unistrut or square tube or angle iron to provide some rigidity, and figure out how to countersink screws so the heads are flush and don't push into the cells through the insulating foam.

But in the end, I'm really not sure how best to modify these. I don't want to use wood in them, but I have near zero metalworking skills and a lack of tools. I didn't think this through very well.

Maybe I'll end up using these as connection/busbar boxes, and will get some Luyuan boxes if they can be made to work with my 230Ah cells without much fuss or extra time. Not sure yet. I just need some time to sit down with the boxes and cells, and do some brainstorming.
 
I’m all in following you down this rabbit hole. I've got boxes on the way and just about zero metal fab experience. I figured I'd buy something like this inexpensive 18" metal brake from Harbor Freight, and find some suitable sheet steel I can cut and bend into restraining brackets that I bolt to the sides of the electrical box. If nothing else, I get to dip my toes into a DIY metal work project to see if that's something I find worthwhile.
 

diy solar

diy solar
Back
Top