Pictures - Battery bank clamp assembly

Sanwizard said:

I used the Facon heating pads attached to an aluminum plate that i covered with Polyimide tape. Seems to work well. Between each cell, I used thin heat resistant rubber floor matting. I covered the inside of my aluminum toolbox with felt, and used cutting boards on top to protect each cell and house the BMS.

Click to expand...

Samsonite801 said:

I made more progress on the 48v banks today. They are both fully operational now. I'm glad I added those 2a active balancers since they come with bluetooth management app, where the two BMS (I bought originally), are unmanaged. It is nice to be able to log into the balancers and see each cell voltage.

It's a challenge to make the wires all pretty because there are just so many (and being all the same length). Oh well, at some point you just give up and accept that it works, not worry as much about a few wires, I guess I could build a cover if I really cared about it that much. Most of the tangled up mess is hiding under the modules there.

View attachment 55079

View attachment 55080

View attachment 55081

Click to expand...

Samsonite801 said:

An important discovery to make note of here in my implementation of a home brew clamp assembly. A fatal flaw in my design...

As I connected up my bus bars, on one pack (seen on right in picture), when I connected the bridge cable (little red cable) on the right-hand side 48v pack, to connect the 2 halves of that pack, I was getting a spark, and could hear a rapid discharge (like a boiling sound from one of the cells). I quickly removed it. The red bridge cable was fine if I bridged the pack on the other end (bottom end in picture). But connecting the 2 halves on the top end between the 2 halves would get a spark...

So I removed all the bus bars, did some voltage testing and found that 12 of the cells across my 3 battery banks, the negative conductor of the cell is grounding to the aluminum clamp chassis. Wow, this is bad. I disassembled all of the clamp assemblies, and found that due to the sharpness of the threads on the threaded rods, some of the cells got pierced (the blue wrap on the battery cells is very delicate, and there is aluminum casing under the blue wrap of the cells, which is apparently the same conductivity as the negative terminal).

So my advice to anyone who is using metal/aluminum clamp assemblies and fasteners which are conductive, check each cell and make sure the blue wrap is fully intact with no breaches, and negative of the cell chassis is not grounding to the clamp chassis in any way. This can cause one or more cells to have impedance or dead-shorting in relation to other cells causing a drain or short on a cell. I had some cells which just had some impedance but not like a full dead-shorting condition. This kind of thing could cause a behavior like you have a malfunctioning cell, or in my case the one which had a dead-short making it obvious for me to find.

So now to regroup in my plan. I am going to put silicone tubing along all the threaded rod sections where they run along the cells, drill the end-plate holes a bit larger to give the wiggle room for extra clearance required with the tubing installed, put some blue electrical tape over the nicks on the cells, and confirm that each cell is insulated from the clamp chassis.

So I just thought I'd mention this, as others may have the same problem without necessarily knowing about it.

View attachment 48146

View attachment 48147

View attachment 48148

Click to expand...

alvirtuoso said:

There's a discussion somewhere in the forum saying something about not to trust the blue casing and use a board separator like capton sheet board or epoxy sheet board. Thanks for the idea and website to order precut materials. I've been looking to do something like yours that's portable enough to fit in a handtruck. I'm thinking of using a liquid electrical tape or liquid rubber like plasti drip to insulate the rods and perhaps the metal plates.

Click to expand...

curiouscarbon said:

silicone tubing to insulate threaded rod is what i will use in upcoming 300Ah cell build, also.

this thread has definitely inspired me to aspire :D

Click to expand...

Samsonite801 said:

Yeah, here is the exact link I bought mine from, it was just the perfect size to fit the 3/8" threaded rod, not too tight to be annoying to put on, but not too loose to flop around, when I put those tubes on, it was one of those times in life I just thought how that was just meant to be

https://www.amazon.com/gp/product/B083TT9TDD

And I have plenty of tubing left for other homesteading projects like pumping water in a greenhouse or something...

Click to expand...

Samsonite801 said:

BTW, finally starting to install the 12v pack in the basement of my Serengeti... This weekend will start wiring it in along with a 250|100 Victron. About time I'm finally getting somewhere... Still aways away from getting the 48v system installed though...

View attachment 71378

View attachment 71379

View attachment 71380

Click to expand...

Sanwizard said:

I still looks like there is no isolation between each cell and between the cells and the frame. Take a look at the yellow panels in the Seplos Mason DIY build for what I mean.

Click to expand...

Samsonite801 said:

Just in case anyone would like to use the same dimensions I came up with on the plates, I posted this screen shot in another thread and though to maybe stick it here as a reference.

The first item is the qty:2 bottomside plates for the two 16-cell (longer) 48v packs

The second item is the qty:1 bottomside plate for the 8-cell (shorter) 12v pack seen in above pic

The last item is the qty:6 end plates which are compatible size for all of the banks (use 2 of them per bank/pack, on each end)...

View attachment 76418

Click to expand...