Rethinking my battery box

[ArthurEld]

You might try something like this to strengthen it where your screws go through.

Everbilt 1-1/4 in. x 72 in. Plain Steel Angle with 1/8 in. Thick 800937 - The Home Depot

This metal angle is commonly used for constructing bicycle racks, bed frames, motor mounts and many other utilitarian functions. Common types of angles include: solid, punched hole, slotted hole and solid

www.homedepot.com

 

[SparkyJJO]

I ordered a set of cut to size carbon steel plates from onlinemetals.com. Inside I'm using some short pieces of unistrut to reinforce the plate and give me a mounting location for my BMS using channel nuts and screws. I thought maybe I'd have enough to put on the outside, but between 2 boxes, not likely, so I think that angle will be a better (cheaper!) option to get the job done.

Again, everything will be lined with neoprene foam to keep things from shorting out.

I wanted to somehow keep it all contained in the box so nothing stuck out, but that would take a lot more work/parts/time, so I'll likely not try to be too fancy.

 

[SparkyJJO]

Over the weekend I stopped at the hardware and got some strut channel, angle iron, and a few nuts and bolts (I probably had some already but for 89 cents better to just buy what I know I need and avoid making another trip). Online metals shipped my plates yesterday.

One thing I need to do is figure out how to sufficiently flatten the two indents where the carriage bolts went. Big hammer? Doesn't have to look pretty, it'll be covered by foam and cells anyway.

 

[OffGridForGood]

If you have a bearing pulling set, use a couple of the flat plates and a bolt to gently pull those flat with minimum damage to the finish.

 

[robbob2112]

I ordered a set of cut to size carbon steel plates from onlinemetals.com. Inside I'm using some short pieces of unistrut to reinforce the plate and give me a mounting location for my BMS using channel nuts and screws. I thought maybe I'd have enough to put on the outside, but between 2 boxes, not likely, so I think that angle will be a better (cheaper!) option to get the job done.

Again, everything will be lined with neoprene foam to keep things from shorting out.

I wanted to somehow keep it all contained in the box so nothing stuck out, but that would take a lot more work/parts/time, so I'll likely not try to be too fancy.

Black neoprene can be conductive if it contains carbon as a colorant. Lots of black things use carbon in some amount. Might not be enough to just measure with a meter, what about a short?

 

[robbob2112]

Over the weekend I stopped at the hardware and got some strut channel, angle iron, and a few nuts and bolts (I probably had some already but for 89 cents better to just buy what I know I need and avoid making another trip). Online metals shipped my plates yesterday.

One thing I need to do is figure out how to sufficiently flatten the two indents where the carriage bolts went. Big hammer? Doesn't have to look pretty, it'll be covered by foam and cells anyway.

View attachment 215318

4x4 or 6x6 and a sledge on flat concrete

 

[SparkyJJO]

Black neoprene can be conductive if it contains carbon as a colorant. Lots of black things use carbon in some amount. Might not be enough to just measure with a meter, what about a short?

........

I had no idea. How do I find out?

i guess I can return it.

 

[robbob2112]

........

I had no idea. How do I find out?

i guess I can return it.

To find out for sure takes a megger meter. Basically if it doesn't say it is good as electricity insulating specifically you don't know.

 

[ricardocello]

To find out for sure takes a megger meter. Basically if it doesn't say it is good as electricity insulating specifically you don't know.

Some black neoprene labeled “anti-static” or “ESD protective” are definitely conductive (but probably about 1 MegOhm)

 

[SparkyJJO]

All it says is this

"The closed cell foam sheet is insulated, anti-slip, damp-proof, soundproof, buffering, corrosion-resistant, shock-absorbing, non-toxic, durable and environmentally friendly, and it be used from -50℃ to 150℃."

https://a.co/d/fQ44TmJ

 

[robbob2112]

All it says is this

"The closed cell foam sheet is insulated, anti-slip, damp-proof, soundproof, buffering, corrosion-resistant, shock-absorbing, non-toxic, durable and environmentally friendly, and it be used from -50℃ to 150℃."

https://a.co/d/fQ44TmJ

Electronics - EVA Foam

Explore the versatile applications of EVA foam in the electronics industry. Learn about its benefits, limitations, and how to choose the right type for your needs.

evafoam.cc

Assuming the description is right it might be ok, not sure I would bet on it.

 

[SparkyJJO]

Yeah can we trust these guys as to what it really is made of.
Is there something else that you'd recommend instead?

 

[robbob2112]

Yeah can we trust these guys as to what it really is made of.
Is there something else that you'd recommend instead?

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Maybe, maybe not.

 

[Brucey]

I think there was a thread somewhere where it was found that st gobain had a compliant foam available that was specifically used in EV battery packs. Various thicknesses etc. Minimum order was in the $200 range or soemthing?

 

[Brucey]

Another Cell Compression Thread, this time about foam

Hi everyone, been lurking in the shadows and finally decided to put up my first thread and post. I've read thru many of compression threads and can say there is much discussion about this subject. My background is automotive, I'll just leave it at that. This is how the EV manufacturers are...

diysolarforum.com

 

[Tulex]

Over the weekend I stopped at the hardware and got some strut channel, angle iron, and a few nuts and bolts (I probably had some already but for 89 cents better to just buy what I know I need and avoid making another trip). Online metals shipped my plates yesterday.

One thing I need to do is figure out how to sufficiently flatten the two indents where the carriage bolts went. Big hammer? Doesn't have to look pretty, it'll be covered by foam and cells anyway.

View attachment 215318

I actually put a large socket on the back side with a bolt and washers from the inside. Put it through the socket with a nut and pulled in into the socket.

 

[Tulex]

This is what I used to line my box and between cells. Couldn't go any thicker, as the cells just fit with what I used.

 

[SparkyJJO]

My metal arrived. Fits perfectly where I need it. Now to get some time to cut strut and angle iron, drill holes, etc.

Figure I'll dry fit the cells and brackets first, then get the rest of the layout done (shunt, breaker/fuse, wiring). I suspect I'll need to use a custom busbar to connect between the two rows of cells.

 

[Nobodybusiness]

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?

Used one of these for my Polaris connectors.
Got mine from Amazon.

https://a.co/d/hTT5Yqn

Used hydraulic punch to pop a meyers hub in it.

Pretty thick metal and gasket sealed so didn’t see any issues with it.

As long as it will fit what you need it should work.