Rewrapping 18650 Batteries




Introduction: Rewrapping 18650 Batteries

About: Automation engineer that loves to make anything that needs electricity, hack and mod things or build anything AWESOME...

Using 18650s without wrap is dangerous since whole body is actually negative terminal. If you use it without wrap your 18650 could short and potentially caught on fire or explode.
If you salvage 18650s from battery laptop battery you could use this guide to rewrap your batteries since most of them are glued inside and only way to get them out is to damage wrap.

As a safety precaution do this when battery is not fully charged, that way if you accidentally puncture or short it it won't release all of it's energy and catch on fire or explode.

Do this on your own risk and please read carefully, if you don't know what you are doing read more about lithium batteries or ask for help.

Step 1: Tools & Materials

You will need :

Heat gun or hair dryer ( lighter might also work, but i wouldnt recommend it)

Ruler or calipers (be carefull if they are metal, so you wont accidentaly short battery)

Hobby knife or scissors

Wrap (i used PVC, 5m - 2$ on ebay)


Paper rings (if old one is damaged)

Step 2: Cutting Wrap

When flat it is 30 mm wide, inner diameter is few milimeters wider than 18650, so about 18.5mm. It is thin so it should fit in flashlights or e-cigs.

I like to cut them 3mm longer on each side, so about 71mm, maybe even 72mm (72mm in this guide)

Protected 18650 are a bit longer, they are not 65mm, they might be 67-68mm so just add 6mm and it should be fine.

Use ruler to measure 72mm and cut with hobby knife or scissors.

You can also make template, and use it to cut wrap instead of measuring 72mm every time.

Be careful to not damage wrap, if you damage it you would need to cut another one.

Step 3: Remove Old Wrap

When you remove wrap cut down on negative terminal, if you cut on positive you might short battery.

If your wrap is damaged you might peel it off with your fingers.
Try not to damage outer casing, or puncture it.

If it has protection circuit, it will have flat piece of metal that goes to top of battery, dont touch that metal and dont bend it. It is dangerous to touch that metal, if you remove insulation it will short battery.

If your wrap is not damaged you can leave it on, but it may not fit in some devices, or it may get stuck.

Only remove paper ring if it's damaged or if it just falls off.

Dont lose paper rings, they will protect battery to not short positive and negative terminal, if you lose it you can buy another one, or maybe even cut it from cardboard or hard paper.

Step 4: Rewrapping

If you removed paper ring, now it's time to put it back on top of battery and put wrap on it.
You should have 3-4mm on each end, depends on how much you left it (3mm in this case).

You can try this on old battery, or 18650s that dont work, even on 18650 that are working, you wont damage them if you dont heat them too much.

Once you put wrap on battery and align it, slowly apply heat to top of battery,swipe gun or dryer from top to bottom and rotate battery.
This should take few seconds, if you leave it too long it will melt wrap.

Try not to heat battery for long time, if you can hold it its not heated too much.

When you are done, you can put some stickers with original info, or maybe write with marker, its your choice.

Step 5: FAQ

Q: Where did you get wrap?

A: Ebay, just search "18650 wrap" and you should find it in many colors and lenghts.

Q: What will happen if i apply too much heat?

A : Wrap will melt, just as i showed on second picture

Q: Can i damage battery while rewrapping?

A : If you dont puncture it, or heat it too much you wont damage (if its protected dont touch protection circuit)

Q: Can i use electrical tape instead of wrap?

A : Yes, but it may not fit in some devices

Q: Can i use this guide on different size batteries?

A : Same thing, just make sure your wrap is right size (smaller batteries like AA need smaller wrap, i like to leave 2mm off each end)

If will maybe expand this, if you need anything, then ask me in comments

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    2 years ago

    Please wear mtb gloves or some other leather gloves and eye protection when you do this.


    3 years ago on Step 5

    My friend.

    My 18 years son hurt himself very badly by following your tutorial As he told me. We were lucky that he got fine after a couple of weeks, but the scars will still for life. And was about to burn the furniture.

    I read your tutorial it was very informing then asked him what he did. He just followed the pictures, unfortunately . Then I knew what happened he pulled out the plastic ring which supposed not to pull off in the first place. with a screwdriver, he managed to short-circuit it. then burned his hand and his chin . I hope you remove the picture for my son's scar sake. Many people do not read the written text they only follow the pictures

    Thank you


    Reply 3 years ago

    Thanks for information, sadly i don't think removing picture will do anything since you can clearly see that ring back on every picture in next step. Most of the times that paper ring is not holding on cell with glue so it will fall off, this is just precaution to not throw it away or forget about it. I am however gonna bold those important things and add warning.


    5 years ago

    well i don't Know

    Why the heck i should rewrap a battery,when it is already wraped.

    any way thats a good instructable.


    Reply 3 years ago

    I have two. The wraps on both were the same - green. I rewrapped them so that one is red and the other is blue. Now, if I ever mix them up, I will be able to tell which one I just pulled out of the vape and which one is fully charged.


    Reply 5 years ago

    if wrap is damaged, it would be nice to rewrap it
    or maybe you just dont like the color


    Reply 5 years ago

    I know, they are really cheap, i will order more colors since i have few different cells

    Should work with hair dryer (i think they shrink on 60-70c)


    5 years ago

    That's a lot of batteries to rewrap


    Reply 5 years ago

    And i will get more of them :D