diy solar

diy solar

First time DIY case

It was 32F this morning and I used a chinese diesel heater to warm the pack. The beauty is it warms my tent too. The black/aluminum tube is the heat output.

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What’s with the odd imperfections on the back top plastics covering the cells?
 
What’s with the odd imperfections on the back top plastics covering the cells?
Great question, I wonder that myself. The cells seem to be working fine like that. I need to add a BMS but for now I'm not too worried. Problably some rejects from China, they stuck me with them and profited handsomely.
 
A few years ago I purchased some Ev breakdown cells. They rewrapped them and put on new tops.

The key thing the customer seems happy with their purchase.
 
Be mindful those cutting boards while seem stiff, will bend and flex over time, just keep an eye on them as they age.
Yes I agree,

i tried to make a compression fitting out of even thicker and harder plastics and it just tends to bend, which places all the pressure on the corners of the cells and not in the middle where you actually need the support.

I suggest running the stainless rods through some cheap aluminium angle iron on the outside of the plastic upright boards to support the bending tendency of the plastic.

Angle iron example:

 

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Yes I agree,

i tried to make a compression fitting out of even thicker and harder plastics and it just tends to bend, which places all the pressure on the corners of the cells and not in the middle where you actually need the support.

I suggest running the stainless rods through some cheap aluminium angle iron on the outside of the plastic upright boards to support the bending tendency of the plastic.

Angle iron example:

The angle iron could also serve as a handle to pickup the pack.
 
I have 3/4 ply but think I should reinforce with angle after seeing that stuff bow over time in shelving applications.
 
I looked at angle iron today and started to think maybe I should use proper material that doesn't need reinforcement. But then I might end up with steel plates 1/2" thick and increase what is already 50 pounds by 20 pounds.
 
I looked at angle iron today and started to think maybe I should use proper material that doesn't need reinforcement. But then I might end up with steel plates 1/2" thick and increase what is already 50 pounds by 20 pounds.
I use 1/4 aluminium plates for end plate compression , mostly because I am very space constrained. I would stay away from steel or AL plates however as they are electrically conductive, so a potential shorting hazard.....
 
Based on feedback from this community I covered the stainless allthread and used plex tubing. It wasn't a simple process because I bought 1/4" inner diameter tube and the 1/4" rod didn't fit through lol. I made it work by running a cut down the pipe and that allowed enough flex to fit the rod through. Ideally I would use proper size but I didn't want to go to the store again and waste the tubing.

Next suggestion was to put something between the cells and for that I'm going to buy the acrylic sheets aka plexi glass and put that between the cells. I inspected in-between each cell and there were some abrasions but nothing even remotely bad.

The blue plastic has tweaked some and I was looking at other materials to use in conjunction with the threaded rods to compress the cells together instead of the 1/2" cutting board plastic. Wood tweaks some too and guys have springs along with the wood so to me that says flexing is fine. So why not let the plastic flex? Do the cells need to be flat, if not why are the corners rounded? I'm curious to hear from those who mentioned the plastic being a problem because of flex.

The local hw store had steel plates but I don't have tools to cut it to size and drill holes. That really would be the best option because the steel won't bend as easily, if there is payoff for preventing a bend. Is there a benefit to preventing the end plates of the battery box from flexing? I checked out some options for wood and there was 3/4" maple plywood which sounds pretty strong, but if the plywood is going to flex then does it make sense to spend $45 when I could just let the plastic flex?

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This 1/8" sheet of plastic is starting to look like a good piece for the top where two grooves could be cut in the blue pieces to slide the black sheet over the cells. When maintenance is needed, the sheet could be pulled out to provide access to the cell terminals. It would also protect from small pebbles getting between the cells when maintence is finished. I had one pebble fall down in there between the cells that needed to be removed because when the pack swells it would pinch the pebble.

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