Is a double layer of shrink wrap on individual cells ok?

Doc3G

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Apr 18, 2021
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Sorry if this has been answered, I tried to search and found a couple of folks who mention that someone could "try it" but no definitive answer on safety.

I have been reshrinking my cells with clear shrink over the original shrink. My thought process was that this is faster than stripping and reshrinking, it ensures no exposed parts of the cell were missed when inspecting the original wrapping, and that it still allows me to see the original battery markings such as date codes.

However, I got to wondering last night if this might contribute to excess heat?
 

daromer

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Oct 8, 2016
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Its ok for apowerwall use. It wont create any extra heat unless you are doing something wrong. Just note that 2x layer shrinkwrap may cause them not to fit in normal holders.
 

Doc3G

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Apr 18, 2021
Messages
56
Its ok for apowerwall use. It wont create any extra heat unless you are doing something wrong. Just note that 2x layer shrinkwrap may cause them not to fit in normal holders.

Thanks. I did double-check that they would fit in the holders and they do, so I'll just keep on shucking batteries for now :D
 

italianuser

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Feb 25, 2020
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Really... I didn't wont to get into this rewrapping business, no no no. @Wolf explained well why it's so important to rewrap cells... but really, no, it already takes so much effort to make a powerwall...
Conclusion: I bought wraps from an online seller, now I'm waiting for them to do my first rewrapping yee! LOL ☺️
 

Wolf

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Sep 25, 2018
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I rewrapped all my frankenstein battery pack cells because all the cells came out of older batteries. Mostly laptop but some medical packs.
One reason was when removing cells from some laptop and medical packs the wrapper was damaged and compromised. Also as the cells were older and who knows where these batteries were stored before I got them. As I opened many batteries that had some form of corrosion, physical damage, possible water intrusion, and some of them had a strong hint of coffee that someone spilled on the laptop and had migrated into the battery. Although many of these cells tested well, once I found 1 cell that had corrosion on it (the cell tested just fine) I was convinced that all cells needed to be checked. So I went about rewrapping all the cells. Good thing I did as I found several others that had severe corrosion on the top (pos) side although there was absolutely no external indication. I had spent way too much time on sorting and picking the best of the best cells to have a corroded cell give me a problem in the future. The additional bonus of the rewrap was a clean and protected cell and of course a nice color combination for my frankenstein pack.
The cells I am processing now all came from clean ninebot scooter batteries and they are 2 to 3 years old. The enclosures in which they came in was clean and didn't look to have been environmentally compromised. Those Cells extracted very well without any tearing or damaging the wrapper so I am not rewrapping them.
 

Doc3G

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Joined
Apr 18, 2021
Messages
56
I rewrapped all my frankenstein battery pack cells because all the cells came out of older batteries. Mostly laptop but some medical packs.
One reason was when removing cells from some laptop and medical packs the wrapper was damaged and compromised. Also as the cells were older and who knows where these batteries were stored before I got them. As I opened many batteries that had some form of corrosion, physical damage, possible water intrusion, and some of them had a strong hint of coffee that someone spilled on the laptop and had migrated into the battery. Although many of these cells tested well, once I found 1 cell that had corrosion on it (the cell tested just fine) I was convinced that all cells needed to be checked. So I went about rewrapping all the cells. Good thing I did as I found several others that had severe corrosion on the top (pos) side although there was absolutely no external indication. I had spent way too much time on sorting and picking the best of the best cells to have a corroded cell give me a problem in the future. The additional bonus of the rewrap was a clean and protected cell and of course a nice color combination for my frankenstein pack.
The cells I am processing now all came from clean ninebot scooter batteries and they are 2 to 3 years old. The enclosures in which they came in was clean and didn't look to have been environmentally compromised. Those Cells extracted very well without any tearing or damaging the wrapper so I am not rewrapping them.

The ninebot cells sound about like the ring cells I'm using. They have 2019 date codes and supposedly have never been cycled. So far (unlike the modem batteries I started with), they have all tested at 100+% of capacity. I don't have a problem pulling the old shrink off, it's not like it costs me anything extra (other than a bit of time), but I just figured that clear shrinking them would allow me to ensure that I don't miss any penetrations in the wrapper while preserving the battery labeling. I also figured that the extra wrapping might make it less likely to have something tear it, which is what got me to thinking about maybe it wouldn't let the cell dissipate the heat, but that doesn't seem to be an issue is what I'm understanding?
 

Wolf

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Sep 25, 2018
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1,461
which is what got me to thinking about maybe it wouldn't let the cell dissipate the heat, but that doesn't seem to be an issue is what I'm understanding?
I think an extra layer of shrink wrapper is the least of your worry as far as heat is concerned. Proper cell selection like the Ring Batteries that are good quality including sizing your powerwall to accommodate your load without drawing excess amperage from each cell will keep your cells and battery cool.
Wolf
 
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