diy solar

diy solar

My DIY 14.3kwh EVE Battery Box Build

Struc

Collecting Parts!
Joined
Sep 20, 2021
Messages
223
Location
Oconomowoc / Land o Lakes WI
Going to chronicle my battery build. Hopefully I get it right the first time so that when I duplicate it for more storage (more batteries are on the way), it will be easier. Didn't want to completely build my own box, so found a nice plastic storage locker that fits the bill quite nicely. Got lucky because I wasn't quite sure of the measurements of the bottom when I purchased online.

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Putting some terminal protection together and took a chance that I could make these work:

Battery Terminal Boots - Amazon

You can squeeze a 20mm bus bar into them, and the final product looks like this:

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The amazon ones work out to about $1.40 per bus bar (1 red / 1 black). You can get these on Aliexpress for about $0.65 per bus bar - just have to wait a month or two (which I am buying more from them).


They actually make covers just for this, but are more like $4.30 per bus bar.


I may see if I can get some heat shrink instead of the electrical tape, but I'm not sure I'm that picky. ;)
 
Going to chronicle my battery build. Hopefully I get it right the first time so that when I duplicate it for more storage (more batteries are on the way), it will be easier. Didn't want to completely build my own box, so found a nice plastic storage locker that fits the bill quite nicely. Got lucky because I wasn't quite sure of the measurements of the bottom when I purchased online.

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wow, so nice, do you have a link for the box ;-). you may add insulation material between the cells, bcoz the cell case are not always isolated from + or -.
 
wow, so nice, do you have a link for the box ;-). you may add insulation material between the cells, bcoz the cell case are not always isolated from + or -.

You can find it other places, but I got mine from Menards. I know they aren't everywhere.
Menards Contico 23-Gallon Storage Locker

The picture is just for general fitment. I plan on securing them better and putting something between them.

Project is temporarily on hold because I'm out of town at my cabin. :)
 
Making progress again, albeit slow. Wanted to get the cells top balanced, so I've been setting them up in 4s config and charging them most of the way up. Takes about 20 hours to get them up where one of the cells starts running away and the BMS shuts it down. That's a real handy little BMS for doing this. Bought it strictly as a tool for charging in 4s config. It has a limit of 10A charging, which is fine. Only thing I don't like is that it doesn't shut down the charging until one of the cells hits 2.75v, and it's not configurable. For $15 though, not too bad. Each 4s group has been taking about 2.4kwh to charge it up, and then I split the pack and put them in parallel and finish the top balance.

Link to Amazon Generic 4S BMS

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Building the 16 batteries in packs of 4 in order to secure them slightly. I'm using some 1/8" high density foam between them to give them some space to expand a bit if they need, but provide a constant spacing for the studs. Using a ratchet strap to slightly compress the pack against the foam, and provide nice spacing between cells but will also isolate each from the next.

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Lesson Learned on the ratchet strap... put some cardboard or something under it when ratcheting. Cut the blue insulation in a couple small spots. Covered it over in tissue paper tape. No biggie. Next pack I'll know better.

Once it was compressed slightly, I wrapped around with the tissue paper tape, top and bottom. Since I have zero extra length across the box, I just covered the cells where they touched in tissue paper tape to insulate them from one another.


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Final config is going to look like this. Not exactly a standard battery design (modified snake??), but it will work well for me. I'm going to want to mount a few things in the lid, so having the main terminals on that side of the box will work nicely for fairly short wire runs. Standard bus bars (72mm) for north/south connections, 85mm bars for east/west. The long bars were off AliExpress and about $2/each shipped. I got 2 packs of 15 to cover future packs.
AliExpress Link to 85mm Busbars

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Been absent in my project, but things should start moving. Spent forever with the layout of this cover for the battery box. Still a couple things to tweak, but this is going to be the final layout. Yes, Class T and a circuit breaker. Only want that Class T to blow in the worst case scenario, so it's a 400A fuse. Circuit breaker is 250A, which is what the BMS is rated for as well. Switch goes through to the outside for On/Off. Still have to punch a hole for the shunt display and wire up the shunt, which will likely be next.

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May I ask the make and model of that dual DC breaker? Is it non-polarized breaker?
The whole thing looks heavy, how much does it weight? Wheel?
 
May I ask the make and model of that dual DC breaker? Is it non-polarized breaker?
The whole thing looks heavy, how much does it weight? Wheel?

I don't have it all together yet, but I would guess it will weigh in at 225lbs+. I do not look for this to be a portable solution. I plan on building it in place. Not even sure these containers I'm using could be lifted without falling apart honestly. I *think* they could, but they are not super heavy duty or anything. More of just a way or organizing everything you need.

The breaker is a Chcyzo. I would expect my BMS to shut down before this breaker would trip, but it's just an extra level of protection. It is marked for a + leg and - leg.

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Nice project. I'm looking to possibly build a similar large battery with 6 Signature Solars

EG4 8-Cell Pack Lithium Cells | 25.6V 100AH

Would you be willing to share what the project will cost?

Thanks
 
Would you be willing to share what the project will cost?

I can spew off a few numbers here, round about. Granted, I bought a lot of things cheap on AliExpress and waited for the slow boat to deliver. A lot of those items were about 1/2 off compared to Amazon.

Contico Case - $40
EVE 280ah Battery cells x 16 - $2450 (Paid $2112 for my cells shipped from China - These were shipped from the US).
BMS - $200
Class T Fuse holder & Fuse - $80
Circuit Breaker - $ 20
85mm Bus Bars - $2 each x 9 (other ones included with batteries)
On/Off switch - $25
Shunt & Display - $ 17
350A Anderson Style Connector Pair - $25
Battery negative Post - $18
Terminal Blocks - $3
1/0 Cable - about 5' - $17
Cable Lugs - $9

So, that totals $2922, round up to $3000 for misc other things (foam, tape, wire ties, small 18ga wire, etc). Hope I didn't miss too much. :)
 
That's a great setup. Thanks for sharing. I went the quick and easy way with 2 Bluettis, but I sure appreciate seeing great components and workmanship.
 
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