# Rewrapping a battery



## HKJ

[size=+3]Rewrapping a battery[/size]







The above battery cannot be used anymore, it will short and might explode. 
The wrapping will sometimes break, luckily it is a fairly simple operation to fix it.



[size=+2]Tools and parts needed[/size]






I am using shrink wrap to repair the battery, due to the heat gun I uses, I have selected a low temperature type.
When flat it is 29.5 mm wide, the inner diameter is 18.5 mm, it will shrink at 80 Deg. C.
I bought a roll with 25 feet (7.6 meter) on ebay for $11 (Sellers name is atop_authentic_auction). This roll will last for more than 80 batteries. Fasttech has heat shrink in 1 meter pieces for less than $1.
This heatshrink is also fairly thin, this is an advantage for some lights.
Often heat shrink is specified in width of the flat tube, the table below shows the minimum sizes for different battery sizes.










As a heat gun I uses a hair dryer, it is not the perfect tool for the job, but it can be used.






I do also need something to measure with, my digital caliper is fine for that (A ordinary ruler could also be used).
With a caliper, remember to cover the jaws or it will short the battery.






To cut the heat shrink I uses scissors.



[size=+2]Rewrapping[/size]






I want the heat shrink tube to be about 3 mm longer than the battery at both ends, with a 68 mm battery this means 74 mm tube.






The new tube for the battery has been cut of the roll.






I uses the fingers to removing the old heat shrink, using a knife or scissors is unsafe.
If there is two layers of heat shrink, only remove the outer layer.






The "naked" battery, do not try to bend the protection pcb out to get a look.






Putting the new heat shrink onto the battery.






There will be about 3 mm extra at each end.









Applying heat, rotate the battery and swipe the heat gun back and forth. If using a real heat gun, be careful with the fingers holding the battery!
It is possible to increase the temperature by covering part of the air intake on the heat gun (This might also melt the gun if overdone).
The battery must not be heated much (As long as it is possible to hold it, the temperature is fine). This is usual not a problem, the heat shrink will shrink long time before the battery is heated.



[size=+2]Final result[/size]



















With a new covering, the capacity information is gone, to fix that I have added a label with capacity. I also included the date I got the battery.


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## cyclesport

Thanks for the excellent tutorial HKJ...I always learn something useful from your posts!


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## Dubois

Brilliant! I just bought some battery shrink wrap from Fasttech, just in case. Now I know how to use it should the need arrive. Thank you HKJ.


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## jaycyu

I found both sellers. Fasttech is a website. I'll order some and see how it goes. Thanks for the picture tutorial.


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## Colonel Sanders

Great info! Thanks! I have a few 26650s and a couple of 26500s that need to be put back in service.


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## gradio

Very nice & clean looking results.


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## jaycyu

Success!
Thanks for the picture tutorial, HKJ.
I bought the shrink wrap from FastTech's site, though they didn't have caution-yellow that fits 18650's.


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## RWeis

I rewarpped a couple of 18650 as per your directions and it was extremely simple and very effective.

Get the material, used a heat gun on low, cut the correct length, get old wrap off, slide new wrap on, center the physical battery, slowly heat shrink wrap, done.

Thanks

Bob Weis


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## Derek Dean

HKJ, thanks for putting together this little tutorial. I've got an 18650 cell that really needs to be re-wrapped, and with your thoughtful directions it now looks easily doable.


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## HotWire

Nice tutorial! I've used Fasttech's 18650 shrink wrap and it's ***perfect*** (and inexpensive). Some automotive shrink wrap is too thick.


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## Norm

This is now a sticky.

Norm


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## walterwitt

Just rewrapped my first cell from an old laptop battery. Got some black heatshrink from Fasttech and it arrived this morning. a few wrinkles and it's a tiny bit off center, but it's a lot better then the electrical tape I had on it before.




















Thanks HKJ.


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## mhanlen

This is a great tutorial. I know for some this stuff seems obvious, but these sorts of step by step tutorials really help a lot of people (and potentially) and help to curb questions.


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## tatasal

So far I have not seen any vendor selling the thicker, clear plastic wrappers used in most protected cells. Any information would be greatly appreciated.


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## HKJ

tatasal said:


> So far I have not seen any vendor selling the thicker, clear plastic wrappers used in most protected cells. Any information would be greatly appreciated.



You can find clear shrink wrap on ebay, but I do not know the thickness of it.
Generally you want a fairly thin shrink wrap or you might have problem with fitting the battery in some lights.


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## kosPap

indeed...the clear wrappers are thicker. I think they are also available from fasttech



walterwitt said:


> Just rewrapped my first cell from an old laptop battery. Got some black heatshrink from Fasttech and it arrived this morning. a few wrinkles and it's a tiny bit off center, but it's a lot better then the electrical tape I had on it before..



what method of heating did you use? I think yuo can work on it a bit more with a hairdryer. the off center is iether because of too uneven heat or not-squared cutting of the wrap


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## jaycyu

kosPap said:


> the off center is iether because of too uneven heat or not-squared cutting of the wrap


: o 
I see


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## LuxLuthor

It's too bad you can't find the typical 1 or 2 mil thick shrink that original cells are wrapped with. Most of the typical wrap sold is 5 mil (=0.005 inch)


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## tatasal

Received from FastTech the 18650 transparent and black shrink wraps. While the transparent are great, the black ones are crap, poor quality. First of all, they are a little loose when fitted, and when heated, it does not shrink cleanly like the blue, yellow (aa) and the transparent ones. Avoid their current black 18650 wraps.

Btw, how do you eliminate the crease on both sides of the wrap to make it look just like from the factory?


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## kosPap

How did you heat it? It makes a difference if you used a good hair dryer or a lighter

I make the main shrinking with the dryer and then work the creases with a BIC lighter. fast and not very close, if you overdo it the transparent wrap will tear on the crease.


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## tatasal

kosPap said:


> How did you heat it? It makes a difference if you used a good hair dryer or a lighter
> 
> I make the main shrinking with the dryer and then work the creases with a BIC lighter. fast and not very close, if you overdo it the transparent wrap will tear on the crease.




I only used a good hair dryer. You never had the hair dryer remove the crease, only with the use of a lighter?


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## kosPap

On the Clear wrap i used yes...you need a bit more localized heat there


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## vectrexer

Excellent tutorial. Thanks!


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## tatasal

kosPap said:


> On the Clear wrap i used yes...you need a bit more localized heat there



It worked! Thanks


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## LuxLuthor

You can get a better result with an inexpensive heat gun than a hair dryer.


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## tatasal

LuxLuthor said:


> You can get a better result with an inexpensive heat gun than a hair dryer.



Saw your link...What noozle type do you use and do use the high or low mode? What is its advantage compared to a hair dryer? I can't seem to remove the crease with the hair dryer...


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## HKJ

tatasal said:


> Saw your link...What noozle type do you use and do use the high or low mode? What is its advantage compared to a hair dryer? I can't seem to remove the crease with the hair dryer...



You get higher temperature with a real heatgun, this is better at shrinking the wrap.
On a hair dryer you can also partially cover the air intake to raise the temperature, you will not get as high temperature as a real heat gun and you might damage the hair dryer.


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## tatasal

HKJ said:


> You get higher temperature with a real heatgun, this is better at shrinking the wrap.
> On a hair dryer you can also partially cover the air intake to raise the temperature, you will not get as high temperature as a real heat gun and you might damage the hair dryer.



Really? I even thought that the heat from a hair dryer's was too much! Ok....

Heads-up: The black shrink-wraps that I got from FT are really bad. It does not shrink evenly..not even properly. Never had any 'successful' finish with it.


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## HKJ

tatasal said:


> Really? I even thought that the heat from a hair dryer's was too much! Ok....



No, hair dryer is at the lower limit. The reason I uses a hair dryer in the above tutorial is because I expect most people has easy access to one.
Usual when I uses heat shrink I uses a real heat gun or sometimes a lighter (It can be a bit tricky).



tatasal said:


> Heads-up: The black shrink-wraps that I got from FT are really bad. It does not shrink evenly..not even properly. Never had any 'successful' finish with it.



It might be because you do not have enough heat.


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## RI Chevy

Try and use a little flame on it. Like a lighter.


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## tatasal

HKJ said:


> No, hair dryer is at the lower limit. The reason I uses a hair dryer in the above tutorial is because I expect most people has easy access to one.
> Usual when I uses heat shrink I uses a real heat gun or sometimes a lighter (It can be a bit tricky).
> 
> 
> 
> It might be because you do not have enough heat.



Using the translucent and even the ordinary blue ones yield good results. The black ones I have are really of poor quality material.


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## Olympus620

I bought some pre cut heat shrink a few months ago and now I am almost out of it. I cannot find anyone anywhere selling pre cut pieces. Anyone out there have a supplier? Sorry for posting on this thread but it seemed like an appropriate place.


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## kosPap

HKJ said:


> No, hair dryer is at the lower limit. The reason I uses a hair dryer in the above tutorial is because I expect most people has easy access to one.
> Usual when I uses heat shrink I uses a real heat gun or sometimes a lighter (It can be a bit tricky).
> .



then there are dair dryers and Hair Dryers. With a good (nominal 2000W) one I have managed to over shrink a wrap in the front of the battery


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## degarb

I have had a few rips in the insulation. Most rips are from getting the cell in and out of poorly designed lights. So, alot just comes down to learning how to workaround lights with too tight battery compartments.

Obviously, this should be a big part of a flashlight review. 

That said, is there a super tear resistant heat shrink? What about double heat shrinking to preempt rips? I hear bedliner spray is tough stuff. What does the fenix arb l2 2600 cells do that we could learn from to better protect their cells?


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## RI Chevy

The batteries that are a tight fit will be even tighter if they are double wrapped. I think one just needs to keep extra wrap on hand to deal with each battery tare as you go.


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## degarb

RI Chevy said:


> The batteries that are a tight fit will be even tighter if they are double wrapped. I think one just needs to keep extra wrap on hand to deal with each battery tare as you go.




I think the scariest was when I tried to put a brand new Trustfire into a tight holder, where the protection circuit sheared off causing a short and the battery to heat up and a sprint to take the cell outside. I still am a believer in protected cells, since once I figured out how to insert properly (or modify holder for more flexibility), the problem should go away in theory. While, a short in the light, water penetration, cord short, or over/under discharging, in real world is more likely, actually a certainty.

The incident does make me appreciate the need for some JB weld to reinforce things and make this near impossible. I sounds like the fenix cells arb l2 may do something like this at first read.

I do wonder if several thin coats of some epoxy over a bare protected cell would offer more "cut" and impact resistance than vinyl tubing. It would be easy to test if I had the time, materials, and cell that really needed repair... As far as epoxy paint goes, there are some good ones, but I am guessing a glue would be better where cost per gram is less an issue.


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## RI Chevy

Maybe you could try and use some very fine sand paper and smooth out rough spots and enlarge the opening a little? I have a few hosts that will only accept unprotected cells. Only my Solarforce hosts will accept the double wrapped protected 3400 mAh cells.


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## LAMPARITA

Old thread but maybe somebody can respond to my question since I'm not familiar with batteries and how they work.

My question: Will like to know if batteries will discharge or get damage if I wrap (using shrink wrap) two CR123A Lithium batteries, one on top of the other, for an easy carry and faster replacement?


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## HKJ

LAMPARITA said:


> Old thread but maybe somebody can respond to my question since I'm not familiar with batteries and how they work.
> 
> My question: Will like to know if batteries will discharge or get damage if I wrap (using shrink wrap) two CR123A Lithium batteries, one on top of the other, for an easy carry and faster replacement?



No, except they may be to thick to fit in the light.

Some companies does sell CR123 batteries wrapped like that, I once got some from foursevens. The foil used was very thin and clear.


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## rc4u

most local hobby shops should have or can get withing two days like my store the battery shrink wrap in various diameters..we stock it for lipos and sub c cells in various sizes...its not expensive and shrinks nice..of course the regular more rubber like shrink does work fine just not as many sizes..but for the most part i guess here the batteries are cr123 or 18650 ect...but just letting you know where to get it and if you need or want WAY better chargers than the wallwart go there also...jeff


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## Richwouldnt

I used precut lengths of wrap from Illumination Supply (illumn dot com) and hit one difficulty. The groove behind the head of the unprotected pack pull batteries I was rewrapping is deep enough so if the shrink wrap is heated too much it shrinks excessively and splits when it shrinks into the groove. Very little shrinking is required which means minimal heat and taking care.


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## kosPap

good point made....happned to me initially.
excess is seldom a good choice


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## Ana

Hi All readers

Great shown with pictures and text, but this material called Layflat heat shrink (if looking for some) is best heated from the middle outwards, so it grips the middle to avoid cold spots appearing to make it unsightly. Make sure you get the right Layflat wall thickness as these PVC heat shrinks start from 0.07mm up to 0.20mm, a general standard is 0.15mm which will accomodate the heat the batteries will give off.

cheers

Ana


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## LetThereBeLite

Just stumbled upon this very helpful post. 

I dropped a 14500 battery from waist high a month ago and the tight manufacturer black wrapping split/tore at the positive terminal side of the battery. 

It was a little annoying as I had just purchased this high quality Panasonic cell. I used a little bit of electrical tape but it's not working that well. Will give this fix a try. 

Thanks for posting this *HKJ*. :twothumbs Very helpful!


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## Arizona_Mike

Thanks for this great post. I've used a lot of shrinkwrap over the years but did not know about the low temp stuff and knowing the needed size and excess length saves a lot of experimentation and money.

I actually have quire a bit of re-wrapping to do. I found a great deal on non-Chinese protected UN 83.3 2600mAh 18650 cells but they are almost 73mm long and fit . . . absolutely nothing! I have had to de-button them to make them usable and I have a little bit of thin vinyl cleanroom tape keeping the original shrink wrap form opening up more where I make the small incision.


Mike


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## 202BIGMIKE

In case of some tears and nicks in battery wraps and you are where you don't have access to wraps and a heat gun to shrink

the battery wrap replacements , you can use Kapton tape. (Google: kapton tape) They make lots of different tapes for electrical 

items. Check them out , see if they have something that fits your quick repair needs. I hope this helps someone in need.


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## Rick NJ

I redid most of my 18650's lately. I used to use regular heat shrink tubing, but with the re-do, I switched over to *fasttech's pre-cut transparent* wrapper for my 18650's. It works out much better for me then the thick heat shrink tubing.

The FastTech pre-cut are *72mm* long and works very nicely when *without a protection board*. With the transparent wrap, I wrap it over the original battery wrap and I know I got good coverage and yet see the original battery markings/labels. I add my label (battery ID, date I salvaged it, and where from) under the transparent wrap. With the original wrap under the transparent new wrap, any scraps/wrinkles made during battery extraction causes the new wrapping to have a bump. This increases the battery diameter just a bit. It works very well.

*72mm is a bit short when a protection board is added*. If the wrapper is 74mm or even 75mm, they would be perfect. The protection board adds 1.5mm. The top-cover also adds another 0.5mm or so even while it is not a button top with a protruding nipple. Room to sneak the wire in (to connect to the protection board), insulation...

[topCover 0.5mm] & [insulation and wire to protection board 0.8mm to 1mm] & [battery 65mm] & [insulation+tape 0.5mm to 1mm] & [protection board 1.5mm]
Total= 68.3mm to 69mm

With redoing the wrapping this time, I am more experienced than the first time and I generally get it down to just around 70mm long. So, *72mm wrapper is too short to grip both ends well*. I usually let the top loosely grip (saving more length for the bottom) and add another layer - this time grip bottom poorly saving more length on top to grip the top well. The *two layers grip both bottom and top well* and (double) protects the bare-wire (that goes from + to protection board) from external scrapping. This triple layer (original+two new layer) battery is not just long, it is also a bit on the fat side. The round wire from + to protection board adds 0.5mm to the diameter plus 0.1-0.2mm insulation paper under it. So my protected batteries (newly rewrap ones) are 69-70mm long, and 18.7-19.2mm diameter.

_*EDIT: updated - with more suitable material to make it shorter and thinner *_diameter *18.54-18.57mm* and *69.25-69.70mm* long

For the *protected batteries*, I decided to redo it one more time since the thick diameter is *not fitting into my (new) second 18650 flashlight*:
- use *fasttech's NON-pre-cut transparent* wrapper
- use *copper foil* instead of wires to connect B+ to protection board

The *fasttech's NON-pre-cut transparent* works well (cut to 75mm+-1mm) so *one layer* will do. With the *copper foil (5mm wide 0.03mm thick) plus kapton tape under and over (total 0.15mm max). * The *copper foil *is *very difficult to handle but far superior to wire*. It is not as thick as 26AWG wire even with kapton tape under and over it. I cut down on the diameter by at least 0.5mm.

With twelve 18650 redone, all diameter range *18.54-18.57mm* and *69.25-69.70mm* long. Now all twelve fits into my flashlights.


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## lumensearch

cracking post, I tend to doubt wrap mine, for a snug fit/no rattle


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## Nazo

I'd been wondering about heatshrink wrap. One thing I've been wondering about though: heatshrink wrap basically appears to be a type of rubber and some is quite thick. Companies generally wrap their batteries with some sort of plastic that seems to at the very minimum be less thick. But I've been wondering: is there anything maybe we could be using that is better than heatshrink wrap for the battery? Specifically, I'm wondering about all the heat that can be generated in some applications (such as many high powered flashlights that can use 2+ amps from the battery) where the battery can get quite warm. Obviously it's not in any sort of danger zone in any reasonable application, but I worry about really long term wear and tear on the batteries due to the extra wear from the heat. (This is partially just a sort of OCD thing for me really. Like I said, I realize they are nowhere near exploding or anything, but they do get fairly warm at least.) Specifically I'm wondering if there might be something that's at least somewhat thermally conductive or at least less resistant than these materials.


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## markr6

lumensearch said:


> cracking post, I tend to doubt wrap mine, for a snug fit/no rattle



Exactly!

I received 20 precut clear sleeves from Illumn last night. I used them to wrap some bare NCR18650GA cells since they're way too loose in most lights and rattle. It drives me nuts. I usually buy button tops to solve this AND to work with lights that require them, but I got a deal on these without button tops. So I just slipped the sleeve on, trimmed a few mm off, and hit it with the hair dryer. Perfect results!

They fit my H600w, just barely, whereas the mtn electronics button tops do not. I'm guessing it's a slight difference in wrapper thickness.


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## Joe Kidd

delete


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## Niconical

Firstly, thank you to HKJ for this, and for all the other amazing and helpful tests, reviews and advice he gives.

I just thought I'd post to say that if you're undecided about rewrapping, it was a lot easier than I expected. I just did 14x 18650 (Eagletac protected and Panasonic NCR-B unprotected) with no problem. I used a hairdryer with directional nozzle thingy, and it was fast and simple. 

I use the Panasonics in various power banks, and constantly removing and swapping them meant each cell had more electrical tape than wrapper. Although they haven't been used that much (maybe 50 cycles each) I was going to dispose of them. Now though for a few $$ I have 10 Panasonics ready to go.

The Eagletac 3400's (green/white) were pretty much cracking and peeling from day 1, so it's great to have them as-new, or actually better than new. Good batts, bad wrapping.

The only downside is that I discovered this thread AFTER ordering and receiving 8x LG MJ1s as replacements, but I'm sure I'll find a use for them.....  

For the record I bought from the same seller as HKJ, atop_authentic_auctions, a strip that I cut to size myself.


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## nitebrite

Thank you hkj! i did not heed your warning even though i have seen this. just a little rip and a 18650 vented. let me tell you, it sucked! very lucky i was not hurt. there was a guy here that was very seriously harmed. since batteries are expensive and they tend to rip there is no reason not to wrap them. i even have the tubing,heat gun, everything on hand but no i did not listen to you. count myself lucky right now
plus in the other thread we see 18650 is harder to get now. so this is very good info.


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## Matt Berne

tatasal said:


> So far I have not seen any vendor selling the thicker, clear plastic wrappers used in most protected cells. Any information would be greatly appreciated.



Hi there, try fasttech, there are some shrink wraps on.


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## Matt Berne

Thank you HKJ, great information!


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## JamisonM

I'm sorry to revive an old thread, but I'm curious how well the PVC heat shrink used for wrapping 18650 cells will shrink onto a AA battery? The only appropriately sized heat shrink for AA cells I can find is from Amazon. I can get quite a bit more if I get this 18650 heat shrink on Amazon and for not much more.


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## Timothybil

Check IMRBatteries. They have a lot of different shrink wraps available in various sizes and colors.


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## JamisonM

Looks like I wasn't searching hard enough. I found a seller on Ebay selling shrink wrap sized for AA batteries. They're also clear which is what I was looking for to keep those darn adhesive labels from lifting up from the sides of my batteries.


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## caram

thanks for this info. I have few batteries that nwed it


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## Arizona_Mike

I got great results with this guide a couple years ago but my cells are a little too thick for some applications. Where are you guys buying your thin/hard heat shrink. I've only found the thick somewhat rubbery stuff which is intended to flex with bundling wire. I have more to re-wrap and I'll probably redo the ones I did before so they fit more applications.

Mike


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## vicgarbutt

tatasal said:


> I only used a good hair dryer. You never had the hair dryer remove the crease, only with the use of a lighter?




You can also use an electric stove elem,ent to generate the heat needed for a nice tite clean wrap


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## Lampas

Nice tutorial, thanks HJK!


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## Mikelights

Thanks for the tutorial, great pics


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## WalkIntoTheLight

Good tutorial. I'll just add a couple of things for flat-tops:

1. Save the plastic insulation ring from the positive end of the battery, assuming it's not damaged. You can re-use it. Otherwise, you'll have to get a replacement ring.

2. If you're using a blow-dryer, you'll have to hold the plastic ring down with a finger, until the positive end starts to shrink (so do the positive end first). Otherwise, the ring will blow out of the tube, and you might have to use another wrapper and do it all over again.


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## POCKET DEBRIS

can a 16340 be rewrapped?and if so where can one find appropriate wrap?


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## HKJ

POCKET DEBRIS said:


> can a 16340 be rewrapped?and if so where can one find appropriate wrap?



Of course it can be rewrapped, you just have to find some shrinkwrap of the right size. You may not be able to find it precut, but may have to cut it to length yourself.
Look for shrinkwrap on Ebay, in Vape shops and electronic parts shops.


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## barthchris

Not as pretty but I just wrap mine in Kapton tape.


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## Slumber

I picked up 2 meters of clear 16340 wrap for less than $2. I use it to add some width to a few CR123's in order to reduce battery rattle on lights that don't require frequent battery swaps. Works well.


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## vadimax

No comments: https://www.aliexpress.com/i/32876306672.html...


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## peter yetman

I see what you mean.
P


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## fmc1

vadimax said:


> No comments: https://www.aliexpress.com/i/32876306672.html...



Thank you for posting this, very informative but unfortunately no surprise.

Frank


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## thermal guy

So I have a few keeppower 18650 that the tail springs on my light have eaten away at the negative end of the battery making for not so good contact. I remember seeing replacement brass “I think”disks for this. But can’t remember where can anybody point me in the right direction? Thanks


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## chrissybabe

After much experimentation I found the best way (for me anyway) to re-wrap a battery is to cut out several pieces of heat-shrink using a guillotine and they all end up being the same length with the ends square.
I use a proper heat gun and try and stick the battery vertically on a small flat spacer so the heat-shrink drops down lower and covers the spacer. Then I get a consistent overhang of the tubing around the ends of the battery. Careful even application of heat is required so that wrinkles don't develop. I saw a comment earlier about how do you get the side creases out. I take the un-shrunk tube, open it out flat so the creases are in the center of the flats then on a flat surface run a fingernail over the crease to 'iron' it out. This seems to work fine on all the different types of tubing I have tried.


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## desert.snake

Shrinking and Kapton tape are very cool solutions, but if nothing is at hand, then ordinary stationery tape also works, only 1 minus, in the heat the glue can ooze from it and you will have to rinse the flashlight from the inside with alcohol, if stickiness bothers, of course. Medical adhesive plaster as well


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## mccririck

Anyone know good places to buy the shrink wrap in UK?


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