GTE battery isolation

[Bigpie]

Anyone able to suggest a repair method for the cell wrapping?

Would electrical tape on the bottom be sufficient, I feel like some liquid coating would be a good method. E.g. https://www.amazon.co.uk/Ganbaro-Electr ... 0BLRJHD54/

I'm going to get my mate to bring his isolation tester again as I did with the other packs before they go in the car anyway.

[Pete9008]

If you can get tape in there then I'd be tempted to use polyimide (kapton) tape. If not then the liquid is the only real option.

Is the metal shell there connected to one cell terminal or is it isolated?

[Bigpie]

The metal around all the cells is isolated, at least with a multimeter on a single module. Will have to get my mate with his insulation test meter to know if it remains so at 400v.

The metal casing of each cell is negative.

[Pete9008]

Is that green film all the insulation or is there something else down between the cells?

You wouldn't want to get a bit of metallic swarf jammed in that gap

[Bigpie]

It's the insulation, like the shirnk wrap on 18650s but seems much flimsier. I'm not sure if there's extra between the cells that isn't present on the bottom, I'd hope so. I'm sure someone mentioned to me that VW did a recall on the GTE pack because of a breakdown of the insulation between the bottom of the cells and the cooler they are normally attached to, but I cannot find any details online.

No, I'd rather not get anything conductive jammed there

I'd want to get something extra in between the metal outer casing here, looks like potential to cause loss of isolation fairly easily

[Bigpie]

This is what Ive come up with, put kapton like tape on there. I've managed to slide some hefty overhead projector sheeting under the lip at the side that's missing the rubber.
I'll do this to all the modules, get the insulation tested, I think his meter goes up to 1kV. Assuming that gives a very large resistance reading, I'll stick em in the car boot.

[Pete9008]

That looks much better. Did you manage to get any tape down between cells?

Your first picture looks like there was a plastic strip between the frame and cells which is missing in the second, is it there on the other modules?

Are these modules the same construction as the ones you already have in the car?

[Bigpie]

It's seems each module is missing one strip. I didn't get anything between the cells. I didn't want to risk tearing what's there, and it seems to not be an issue at the moment.

They are the same modules as the other 2 packs, but those are still attached to the cooler plates.

[Pete9008]

Ahh, that makes sense now! Looks like nicely engineered cooler plate, seems a shame to lose them but it does look like they take up a lot of space.

Do you have the coolant loop connected on the other modules or have you found that it isn't needed (wondering what to do on mine)?

[Bigpie]

Not connected on the others. Newest lot didn't include the cooler, I did about 180 miles last weekend, which was 3 rapid charges up to 100a and some AC. Batteries were still under 30 degrees C when I got home.

Ive no plans on adding cooling based on this, current with be even lower to each cell with 3 packs.

[Pete9008]

That's good to hear. How did it cope with the cold weather, would cell warming have been worth having?

[Bigpie]

It would be a nice to have, they sag more when cold but I've read the GTE still does regen down to -20 degrees C.
I charge a little slower under 0 and don't rapid charge under 5 degrees just to be a little kinder but don't think it's worth the extra complexity and risk of leak unless you want to push the cells

[Bigpie]

Ive found this thread where someone pulls the modules apart https://endless-sphere.com/sphere/threa ... st-1517026

The look to have some thicker isolation matting between the cells so happy days.

[whereswally606]

hey big pie. do you mind me bring my pack to you in the env200 and applying your fix to the muxsan pack? I dont like the idea of taking the cells apart like the bike guy on ESphere, his soldering of the cell link left alot to be desired. (ok on a bike that you can jump off of and run away from though i suppose)

[Bigpie]

You can bring it if you want, we can hookup the isolation monitor and see what it recons the value is. All I've done is slide in some overhead projector sheets. Not sure if it'll fix your pack.

[whereswally606]

it might, its worth a shot i think. Its either that or retire it completely.