Tutorial: Rewrapping a battery

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HKJ
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Tutorial: Rewrapping a battery

Rewrapping a battery

DSC_1789

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.


Tools and parts needed

DSC_1801

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.
diameter

DSC_1802

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

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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.

DSC_1804

To cut the heat shrink I uses scissors.



Rewrapping

DSC_1790

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.

DSC_1792

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

Unwrapping

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.

DSC_1791

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

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Putting the new heat shrink onto the battery.

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There will be about 3 mm extra at each end.

Shrinking Shrinking2

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.



Final result

DSC_1798 DSC_1797

DSC_1799

DSC_1800

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.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

Edited by: sb56637 on 02/28/2013 - 08:17
ryansoh3
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Awesome tutorial, thank you very much!

I would just like to add that a very similar or even the same wrap used by HKJ is avaliable at FastTech at 1m units:
http://www.fasttech.com/products/1140200

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Richie086
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Thanks for posting this HJK. One of my Trustfire 26650 5000mAh cells is starting to loose part of the wrapping. I’ll order this shrink wrap and make the fix.

Also glad to see I’m not the only one that uses labels to print the purchase date on the cell Wink

Richie

ryansoh3
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Richie086 wrote:
Thanks for posting this HJK. One of my Trustfire 26650 5000mAh cells is starting to loose part of the wrapping. I’ll order this shrink wrap and make the fix.

Also glad to see I’m not the only one that uses labels to print the purchase date on the cell Wink

I’m not quite sure if the shrink wrap will be able to wrap a 26650 cell, might be too wide… 0:)

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Richie086
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ryansoh3 wrote:

I’m not quite sure if the shrink wrap will be able to wrap a 26650 cell, might be too wide… 0:)

Thanks for the heads up. I’ll take some measurements of my cell and find the correct diameter for a 26650.

Richie

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No problem, I’m sure you’d figure it out sooner or later. Silly

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That Ninja Guy
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Thanks for the great write-up!

HKJ
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ryansoh3 wrote:
I would just like to add that the same shrink wrap that HKJ used is avaliable at FastTech at 1m units: http://www.fasttech.com/products/1140200[/quote]

It is not exactly the same, the one I uses is without glue.

Richie086 wrote:
Thanks for posting this HJK. One of my Trustfire 26650 5000mAh cells is starting to loose part of the wrapping. I'll order this shrink wrap and make the fix.

You have to get something that is slightly above 26 mm in diameter

Richie086 wrote:
Also glad to see I'm not the only one that uses labels to print the purchase date on the cell ;)

My experience with pens is that the markings does not last, with these labels it will last.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

ryansoh3
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HKJ wrote:

ryansoh3 wrote:
I would just like to add that the same shrink wrap that HKJ used is avaliable at FastTech at 1m units: http://www.fasttech.com/products/1140200

It is not exactly the same, the one I uses is without glue.

Thanks for pointing that out.

Do you know how different it will be with the adhesive?

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That Ninja Guy
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HKJ wrote:
Richie086 wrote:
Also glad to see I’m not the only one that uses labels to print the purchase date on the cell Wink

My experience with pens is that the markings does not last, with these labels it will last.


I use an industrial Sharpie for all my cell writing, haven’t had issues with it yet…
HKJ
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ryansoh3 wrote:
HKJ wrote:

ryansoh3 wrote:
I would just like to add that the same shrink wrap that HKJ used is avaliable at FastTech at 1m units: http://www.fasttech.com/products/1140200

It is not exactly the same, the one I uses is without glue.

Thanks for pointing that out. Do you know how different it will be with the adhesive?[/quote]

I have not tried with adhesive, but I will not expect any different when rewrapping, the final result will probably be a bit stronger.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

Werner
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ryansoh3 wrote:
Awesome tutorial, thank you very much!

I would just like to add that a similar wrap used by HKJ (this one with adhesive) is avaliable at FastTech at 1m units:
http://www.fasttech.com/products/1140200

I have ordered this shrink and it is without adhesive glue whatever…just blue plastic which is a tight fight on a 18650.

pictures in another thread:
http://budgetlightforum.com/node/17907#comment-314389

I also rewraped a 16340 with the fasttech shrink, this worked but the wrap doesn’t get perfect plain…

ryansoh3
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Werner wrote:
ryansoh3 wrote:
Awesome tutorial, thank you very much!

I would just like to add that a similar wrap used by HKJ (this one with adhesive) is avaliable at FastTech at 1m units:
http://www.fasttech.com/products/1140200

I have ordered this shrink and it is without adhesive glue whatever…just blue plastic which is a tight fight on a 18650.

Thanks for the confirmation!

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Streamer
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Nothing but red x’s…can’t see the pics.

HKJ
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Streamer wrote:
Nothing but red x's...can't see the pics.

Looks like the server is down, it will probably not take very long before it is up again (I uses a hosting service).

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

CheapThrills
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Cannot see pics at the moment.

HKJ
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CheapThrills wrote:
Cannot see pics at the moment.

They are back again.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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Nice, thanks!
I have re-wrapped some batteries, did not bother to measure the wrapper before cutting. Just estimated it by eye.

I think after re-wrapping it feels at least as much if not more durable than before.

stevetexas
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HKJ gives good advice.

I use a Laundry Marking pen from the Office Supply to mark cells. This is better than the so called “permanent marker”. The Laundry Markers are the ones that never wash out of clothes, even in hot water. Don’t get it too oily before you mark it.

If you mark it….better check your spelling first, you ain’t gonna change it.

ek9cv5
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Thanks for the tutorial

Don
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I have several metres of green shrinkwrap suitable for 18650’s – anyone in the EU who wants some – PM me – the cost will be the postage plus a few pennies. The cells I needed to rewrap have been rewrapped. Happy to supply it in 75mm chunks. And don’t pay till it arrives. Experience there.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

arjay
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Thanks for the tutorial!

Question, isn’t the heat shrink too tight? I know that you need your heat shrink to be 3-5mm wider than what you intend to wrap. If the typical diameter of a 18540 is 18.5mm, how does your 18.5mm shrink wrap fit with a bit of room to spare? I was wondering if I should go a bit bigger by 3-5mm to be safe.

Don
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The internal dimeter (unshrunk is 18.78mm). “Circumference” of the flat stuff is 59mm. So 59/pi gives the “diameter”.

 

The numbers from my light tests are always to be found here.

https://spreadsheets.google.com/ccc?key=0ApkFM37n_QnRdDU5MDNzOURjYllmZHI...

Werner
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it is tight but it works, like i mentioned this shrinks not so much thats why my 16340(16mm diameter) is not so tight shrinked than my 18650.

HKJ
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arjay wrote:
Question, isn't the heat shrink too tight? I know that you need your heat shrink to be 3-5mm wider than what you intend to wrap. If the typical diameter of a 18540 is 18.5mm, how does your 18.5mm shrink wrap fit with a bit of room to spare? I was wondering if I should go a bit bigger by 3-5mm to be safe.

No, as long as it can be pulled over the battery it is fine.

I have added a table with diameter and minimum width of the heat shrink tube for the common battery sizes. If you buy from somewhere where they do not specify that it fits a specific battery, I would recommend to get at least 1 mm extra.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

NightCrawl
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The larger the heatshrink, the thicker it will get. So for most flashlights its best to use a heatshrink that doesnt have to shrink very much.

arjay
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Thanks for clearing that up guys. I didn’t want to end up picking up the wrong ones.

monanoke
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Thanks for the write up HKJ. Just broke the wrapping on one of my keeppower 18650 and was looking for the wrap to fix it.

a

C

ILIKEFLASHLIGHTS
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That is actually easier than I thought.

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nice crisp tutorial thanks!

Wink

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awesome tutorial

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