Rewrapping 18650s hints and tips?

I've only done a couple of them. I tried a hair dryer and didn't get anywhere. But a lot of people have used them and got the job done. Maybe some hair dryers are hotter than others. I used a heat gun.

The hard part for me was getting the length right. The wraps I got were oversized so I had to cut off 1/4" or so. I wasted a few that I cut too short. You can't really tell if you got that right until it's shrunk on, then it's too late. Guessing after you've done a few you know how to get the length right.

And the scary part was getting the old wrap cut off at the Pos end. You have a blade of some kind right next to the narrow gap between the pos and neg. Got to have steady hands and nerves of steel.

I am also interested in hearing some opinions here. I used my girlfriends hair dryer and it wasn't hot enough.

Also interested. Just ordered 20 wraps to rewrap some of mine.

I'm a man, and I can change, if I have to, I guess.

Don't be afraid to get your hairdryer up close to the battery. I used a weak hairdryer the first few times had to put it pretty close. Having some oven gloves on helps. Let the battery cool down for a few hours.

Get (e.g.) this: $1.47 18650 Battery Sleeve PVC Heat Shrinkable Tube Wrap (50-Pack) 50-pack - 72*30*0.08mm / translucent at FastTech - Worldwide Free Shipping

...and that: $1.47 Paper Insulation Gasket for Flat 18650 Battery (100-Pack) 100-pack - 17mm diameter at FastTech - Worldwide Free Shipping

I prefer a normal lighter flame to shrink...works very easy.

englishmick said:

And the scary part was getting the old wrap cut off at the Pos end. You have a blade of some kind right next to the narrow gap between the pos and neg. Got to have steady hands and nerves of steel.

Click to expand...

(Cut it at the negative end and peel.)

Don't be afraid of using normal flame...it is he easyest way in my opinion. I just keep the batteries between my thumb and index finger.

Rewrapping 18650s hints and tips?

I actually Do. And I stumbled onto a New Tech the last time I did a Battery.

1 - Cut your wrap so there is about 3/16" - 4.5mm of Excess on Both Ends.

2 - Center the Wrap on the Battery and grip it at the Center of the Battery.

3 - Heat the Negative End of the Battery while Rotating the battery. When the Negative End shrinks flat, put the Negative End on something Flat and Heat Resistant like a counter Tile or a Diner Plate.

4 - Now with the Battery Standing Upright with the Negative End on the Tile/Plate, put the Insulator Ring on the Positive End. Now put your Index Finger on the Flat Top/Button Top to keep the Insulator from Blowing away in the next step.

5 - (Here's the New and Improved Tech) With the Battery still on the Tile/Plate, and your Finger still on the Flat Top/Button Top keeping the Insulator in place, Point the Blow Dryer at the bottom portion of the battery until you see the Wrap start to shirk. Now Move the heat Up the Battery chasing the Shrink until it gets to the Top and Curls over the Insulator.

6 - Now the Insulator should be trapped enough that you can just keep your Finger on the Top of the Battery just to keep it from falling over.

7 - Rotate the Battery about 90 Degrees or so and Repeat Step #5.

8 - Once the Sides are gone and the Top is Pretty much Curled Over, give the Top a Good Blast to heat it up and then Immediately press the Top into a Towel or wadded up T-Shirt.

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The Tech of Chasing the Shrink Up the Battery tends to keep Minimize Air Pockets and Wrinkles. And allows you to put More Heat onto the Wrap without Blasting your Hand at the Same Time.

ETA: Most of the Pre-Cut wraps I have bought come cut a Tad Too Long. And need to be Trimmed by .125"/3mm or so.

If you are having a hard time getting the Negative End or the Positive End (or Both) laying Flat, it is usually a Good Sign that the Wrap was Too Long.

All good answers. I've been fine with a hair dryer on high, no idea if it's considered a high power or not. To get the old wrap off, I use my ceramic tweezers, starting on the negative end. Once I get some plastic off it's easy to tear the rest with your fingers. Yes, you could use a blade so long as you're only touching the negative end, but I like a non-conductive something just because.

It's also a good idea to buy a little sheet of extra insulators. they're handy to have around for those times you either blow the insulator off and can't find it (you usually do, but not until the next day under the radiator) or it is somehow damaged.

Blow-dryers will work but can be time consuming, and ends up heating up the whole battery (not good). Heat guns heat a lot faster, but they also heat a lot of surface, and can be awkward, even dangerous as they do put out a LOT of heat.

What I found works best is a little soldering pen (butane) with extra heads, one head being for heat, and it works amazingly well. It provides lots of instant heat so it can be concentrated on the wrap, but you need to take the time to balance a proper distance to "activate" the shrinking and not melt it.

My little kit looks like one of these (link provided for example only) : Iroda SOLDERPRO 50 Cordless Butane Soldering Iron 4 in 1 Kit )

Tips:

1) cut the old wrap at the bottom and slide it out at the top. You should never go anywhere close to the positive with any tools. A wrap once cut or broken is very easy to pull off or apart. Make sure that the insulating ring stays on or ensure that you don't lose it. Try not to touch the top where the positive end is as this is when your battery is vulnerable. If the ring is damaged in any way, replace it. I have some that have a sticky side, which I prefer as it ensures that it'll stay in place.

2) measure your wrap first, cut it if needed, cutting extra length that would be in the way afterwards is a pain and can result in an "opps" and wrecking/wasting the wrap. You should have the wrap long enough to cover the two ends by a couple of millimeters as it folds.

3) The goal is to heat the wrap fast so that the shrinking happens while not heating the battery itself ( or as least as possible), nor end up burning the insulation ring.

4) The higher the heat source, the faster you should move it, you do NOT want to melt the wrap, nor exposed the battery to the heat. Start on the top end where you should make sure that you have the insulation ring in place, shrink the wrap so that it holds the ring in place, then start moving downwards, spinning the battery evenly as you do it. Once you figure out the correct speed to rotate the battery while figuring out the distance from the heat source, you'll balance things out and get to the bottom area where you'll flip your fingers to hold the battery from the top, and finish the bottom. The important part here is learning to spin the battery as you do it as you want the wrap to be evenly shrunk.

5) you need to ensure that the wrap is snug, as if loose, it can rip a lot easier.

Joergl100 said:

Don't be afraid of using normal flame...it is he easyest way in my opinion. I just keep the batteries between my thumb and index finger.

Click to expand...

It's not dangerous to use flame? Just want to be sure before I try

ChelsB said:

It's not dangerous to use flame? Just want to be sure before I try

Click to expand...

To an extent it shouldn't be but it still can be it you aren't careful...you have to move it around a lot, if you stick to one place, you'll melt the wrap very easily, expose the battery to heat in a bad way, and the closer to the positive end, the more you have to be careful, insulation rings can be paper, and they'll catch fire.

Just hold the battery with the wrap at the other end that you're doing, and rotate the battery while you move the lighter (and use a regular flame lighter only, NOT a torch type) back and forth in a fairly rapid way, and it should be fine. Just don't hold it too close. The goal is to not stick to a single spot at all, lots of movement to get the right amount of heat to get the wrap to shrink, and no more than that.

Forgot to mention a little silly warning about using a lighter: it can be fine if you do it right, BUT the lighter can get quite hot in your hands, and metal guard on it can become quite a hazard as it can take a good minute or more to get a wrap done when you aren't used to doing it.

Because of a lighter getting very hot, you might rush and end up melting the wrap, so be aware that you might end up needed a few extra wraps to practice with.

IF you really mess up and the battery does end up overheated, as if you ever get to the point of not being to hold it anymore, recycle that battery (or get it tested by someone that can test it properly), don't take chances.

ALSO (very important): Make sure that you do this is a safe environment, and have safeguards in case something does go wrong, fire catching, battering venting. etc.

ALWAYS SAFETY FIRST!!!

Personally, I would never advise using a lighter. Too much potential for things to go wrong and if you heat up the same spot for too long then you run a much greater risk of causing internal damage.

A medium powered hair dryer should be plenty of heat to shrink the wrap. If the dryer is kept moving and far enough away from the cell then I feel it's far safer than an open flame next to a battery. I also like to do a few cells at a time and do them in stages. First do the bottom halves one at a time. Then starting with the one that was done first do the top halves one at a time.

I use a torch also, hold cell in the palm of my hand ( between middle fingers )and start in the middle and work down to positive end, rolling it with my thumb.
Spin it around and work down to negative end.
Never gets too hot, moving it in quick back and forth motion.
If I can feel the heat in my hand I'm doing it wrong.
Takes seconds.
Also have had to trim off about 1/8-1/4" of any re-wraps I have used.