Please review my battery pack so I don't make a 🔥

Was that link braid pre tined or plain cooper.

I suspect the solder flowed to close to were it was flexing and stiffening it all up and putting the flex in one very small. space as it flexed repeatedly in this small area it started braking the strands. Increasing resistance increasing heat and work hardening the copper. This ends up been a self perpetual cycle that escalated untill catistrofick fault you end up with there. This is what I think most likely happened from working on large factry mechinary that vibrates and seen similar results with stranded copper.

I think your better of with the copper braid over the silicon wire just make sure there’s more space between the stiff soldered area. (I prefer the pre tinned stuff personally as I fined it easya and quicker to get the solder contained were I want it for a better more controlled concetion)

Disclaimer this is my opinion I’m sure otheres will have different or contradiction ones i recommend reading them all and making your own mined up to what you think is best.

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Just finished my 12S4P for my new project.

I ordered the 30Q with the Tags from nkon.nl every row of my holder has 8 batteries and there is a total of 6 rows (8x6 = 48 cells = 12s4p). I connected 4 of them in parallel and then connected to the next pair of 4. So it means each row has 2 parallel pairs. For connecting the parallel pairs I used a thicker wire because the tag only would not have a desirable amp rating by itself.

So I just soldered the parallel pairs together with the tags. If you have a soldering iron that can get hot enough and you sand the tags a bit then it will hold up quite well.

Just don’t want to invest in a spotwelder that I only use once every 2 years.

The case and everything is printed on my 3D Printer (Material PLA)

To improve shock absorption the cells have acrylic and hotglue between the cells.

image image image image image image

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What about fish paper? 🤷

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With sturdy spacers, imo not needed. But if the spacers are prone to cracking bending or melting… I still say not needed, and get better spacers.

Mechanical stress is a real thing that can be a strong factor to this; I’ve had big issues with it on my packs as well:

btw you can get neutral cure silicon amazon prime!

https://www.amazon.co.uk/gp/product/B005X685NK/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

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Here’s some pictures of my latest battery build- 0329191311 0329191229a 0329191316 0331192234 0329191315 0331192215a 0331191701 0401191900 0329191610 0329191616 0331191756 0401191901a 0329191610b 0331191704 0401191901

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Is there a reason why you out the fishpaper everywhere but not between the p-packs?

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There is fishpaper between the ppacks but only where terminals touch in the picture below there is fish paper where it’s red but not where it’s blue. Screenshot_2019-04-02-07-19-07~2

the blue one was my question.

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Where the blue is there are no terminals of the battery so nothing to touch and short.

but it´s the place where the battery flex. because of this flex the packs can rub on ech other and damage the thin plastic cover around the cells. as you for sure know the main part of the outer cell is the negative pole. so if two packs damage there isolation next to each other over time you short your packs.

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@Andy87 Thanks for pointing that it i will definitely take that into consideration for future builds and possibly add some fish paper there on this one. however there is kapton tape over the positive cap and there are 2 layers of shrink wrap one over each of the parallel packs that fold inward a bit and covers most of the positive cap and one over the 2 parallel packs that are next to each other so the chances of it shorting that way are very slim.

Andy’s talking about the cell bodies rubbing together and wearing through the insulation. Cell bodies are attached to cell negative.

He’s not talking about the caps/terminals.

Fish paper is more abrasion resistant than kapton or shrink wrap.

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@deucesdown I get that but the main problem would be the positve cap touching the cell body which is negitive but if the positive cap is covered it cant short on the negitive cell body.

If you have a connection from positive on one to negative on the next group in series, and the wrap wears between those groups, the cell bodies contact and essentially short positive of the first through the negative (body) of the next which is the negative of the first. It’d be like shorting positive to negative on the first group directly, just via the cell bodies.

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Issue still remains I believe because the cells that are stacked “further” into the series don’t actually have 0V on the GND side they have all the voltage from packs before them.

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@Andy87 @deucesdown @wafflejock There is a very slight chance this will happen but just to be safe i will add fishpaper in this area on this pack and in future packs!

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This is worth reconsidering. Imagine what happens if you connect cell negatives of two touching P-groups together.

The chance may or may not be slight. The consequence is pretty serious.

I’m only harping because this is the “review my pack” thread! :slight_smile:

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@Andy87 @deucesdown @wafflejock Fishpaper has now been added between the P-groups! 0402191830

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