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[RECOMMENDATION] The perfect battery box for DIY 8s EVE 90/105Ah ?

meetyg

Solar Enthusiast
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Jun 4, 2021
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After a long and frustrating search for a battery box for my DIY 8s pack, I think I've found the best one (for my needs at least).
For my solar needs, I am building 2 x 24v Lifepo4 batteries that will be in parallel, each with its own BMS.
I'm using EVE LF90K cells.
I originally bought some boxes designed for 280Ah cells. It works out well with these, but they are a bit big for my needs. The place where I plan to place the inverter and batteries in the house is somewhat constrained. The 280Ah boxes were too deep (obstruct a door) at around 19cm.
Here is how the cells look in the 280Ah box:
20221016_120954.jpg

So then I bought some other slimmer boxes, but they were too short for the 20cm height of the EVE cells (which doesn't include the terminal studs, which are around 1.0-1.5cm), so the lid doesn't close.
Frustrating...

But recently I found these on Alibaba:


Their total height (lid included) is 23.5cm, and depth is 17.2cm.

Here is how the cells look in the new box:
20230323_161454.jpg20230323_161458.jpg20230323_161506.jpg20230323_161556.jpg

I had to use some force putting them in, because originally I had attached adhesive 1mm thick EVA foam to each cell (as a separator/isolator). But it helps keep the cells compressed and tight in the box, so no other compression is needed (I suppose).

As you can see the lid fits fine and there's room for a BMS alongside the cells.

The only downside to this box, in my opinion is that you need to glue it shut (no built in threads/screw holes for the lid). This is important because the strap that came with the boxes is only attached to the lid. So you need to be careful carrying it around, as these batteries are heavy. I wouldn't count on it even if glued. In my case they will be stationary (other than maintenance or re-balancing if needed) so it's not critical for me.

BTW, those marks on the inner side of the lid terminals are not burn marks, just some excess epoxy or whatever they use. Not major, I will scrape it to get a clean terminal.

I know many on the forum have been looking for a battery box for these EVE 90/105Ah cells and I think this is a good solution.

It was shipped in a few days and seller accepts PayPal. The downside to this order was the expensive shipping (to the Middle-East) without any cheaper options. But it came super fast via FedEx, so it was worth it.
Do note that they have a minimum order of 2 boxes. The boxes themselves were pretty cheap. All in all it cost more or less like the boxes I previously ordered from Aliexpress.

Beware that there are similar looking boxes available online (Amazon, Ebay, Ali, etc...) but thier total height is only around 21-22cm, but the inner dimensions of the box is only 18cm, so not suitable for these cells.

Hope this helps some of you...
Happy DIYing!
 
Last edited:
Just a note, after trying to complete the build with one of these boxes:
Depending on hardware used (busbars, wire thickness, and screw sizes) you might find that the height still isn't enough. It turns out that while the lid fits perfectly when just the cells are inside, it might be a problem when connecting the positive/negative wires to the lid terminals. It's just so tight, that you could potentially have the M8 screws touching one of the busbars/terminals of the cells, while closing the lid.

I did some improvisation for now, but I think that for the long run, I might have to 3d print some "stilts" for the lid (which I was trying to avoid in the first place). Kinda like what SunfunKits did in early builds of thier kits.
20_20210806175018656.jpg

Anyways, here's how it looks like now. But now the lid doesn't fully close:
20230324_145526.jpg
 
looks like they are making an 8s version using 105 cells:
That's nice!
The thing is, they are using those bulky boxes for the 8s too.
I have some space constraints so I couldn't use the 280Ah boxes. I actually started out with those just to discover that thier width was problematic for my use.

Just an update: A friend at work 3d printed a "riser" peice for my boxes. It allowed me to use these more compact boxes, and made all the wiring fit nicely.

20230420_200635.jpg20230420_200710.jpg20230420_200559.jpg

If anyone is interested, I could ask him for the 3d files. Due to size constraints of our 3d printer, it had to be printed in two halfs.
But it's still fine. I silicone glued the risers to the box.
 
How will you keep the cells secure so they don't move around in the case? Will be stationary?
It will be stationary, but I still used some EVA foam (with one side adhesive) between the cells. This creates some compression on the cells and they don't move around.
 
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