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Old 12-12-10, 06:39 PM   #1
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Can these 18650's be saved?

18650's are held together by the thin plastic film coating. I dropped one on the concrete today and the film broke and the end of the battery is now exposed. When I checked the other battery the film on it is cracked and ready to give way. Both of these batteries still have a charge.

Any way to fix the film coating so that I can continue to use the batteries?
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Old 12-12-10, 09:17 PM   #2
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I'll be more worry with the condition of the electronic protection board. Dropping on it may have damaged them. Although you get a voltage reading from them, there is no telling if it will still protect from over discharge drain, over charge voltage or short circuit.
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Old 12-12-10, 09:54 PM   #3
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Well, luckily I only dropped the one. I was going to pitch it but thought I'd see if it was still safe to use. If so, I was wondering if anyone has experience fixing them....................
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Old 12-12-10, 11:16 PM   #4
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The board on one of mine failed so I removed it. I know it is no longer protected, but the lights I use it in have low voltage cut off at about 3.2 volts. The charger has never charged over 4.19 volts on my Fluke.
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Old 12-13-10, 09:40 AM   #5
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coat the exposed area with crazy glue (don't get it on the conductor end-area)
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Old 12-13-10, 09:19 PM   #6
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Is there any way to know if the cells are functioning properly? I have no reason to believe they aren't but I want to be careful. The broken one tests the same as the good ones, with the voltmeter, anyway.
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Old 12-14-10, 01:04 PM   #7
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Test it by plugging into light and monitoring voltage & amperage as it discharges. If the light has a constant-current regulator, output from the battery should be constant. Then see if battery shuts off at 3.2v, that's typically where the protection boards cut off.

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Old 12-14-10, 11:32 PM   #8
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Clean off the dirt, the wrap some electrical tape around the area to insulate it again. Perhaps use super glue to glue the tape to the shrink wrap so the sticky stuff doesn't stop working as it often does.

If you can find shrink tubing large enough to fit over the battery (stretching it can make it somewhat bigger), put it over the bottom of the battery, then shrink it, then cut off the excess. This might leave you with a battery that doesn't fit in the flashlight, however -- if the tubing is thick anyways.

If you want to get fancy, use some of that rubber stuff they sell to coat tools to give them rubber handles and paint that on and let it dry.

You could rip the protective circuit out entirely. But if you do that, you'll need to make sure your charger shuts off properly and you'll have to turn your light off before it gets too dim, or it will ruin the battery.

Or just order new ones from DX -- they're only $4 per battery.
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Old 12-15-10, 09:29 AM   #9
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You can go to a hobby store, especially ones that deal with remote control cars, and get the heat shrink for batteries/battery packs and redo the shrink wrap around it.
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Old 12-15-10, 11:29 AM   #10
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You can go to a hobby store, especially ones that deal with remote control cars, and get the heat shrink for batteries/battery packs and redo the shrink wrap around it.
Bingo.

Thanks
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Old 12-15-10, 03:39 PM   #11
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You can go to a hobby store, especially ones that deal with remote control cars, and get the heat shrink for batteries/battery packs and redo the shrink wrap around it.
I did suggest that already, but there's one problem here ...

I deal with R/C airplanes, and I've never found heat shrink at the hobby shop -- they always sold assembled battery packs and not the materials for making your own. Perhaps other hobby shops are different, but none around here seem to cater to people who make their own packs. I always had to order it, or get it from somewhere else. Here's a place you can order it, and I've always been very happy with radicalrc. Of course, the problem here is that you'll pay as much for this as you paid for the battery, even with their reasonable shipping costs, though you will have enough to fix several batteries.

The local Fry's sells shrink tubing, but I'm not sure they sell anything wide enough to cover a 18650 battery (but they come close -- by stretching it out, it might work.)
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Old 12-16-10, 09:46 AM   #12
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dougmc, That is why I suggested a shop that deals with RC cars specifically. The electric racers almost always build there own packs (take a bunch of batteries, run them through tests and pick the matching cells, etc.). I did it a couple of times but man what a pain. Maybe we just had a good hobby shop where I lived (funny that it was run by the guys that built there own planes also...hmmmm). I know that now-a-days it might be harder to find a shop like that with our national chains and margins being what they are.

Heat shrink tubing isn't something that will stretch and work, If it doesn't fit, don't force it.

Here is a quick find:
http://www.batteryspace.com/78-3widthpvctube.aspx
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Old 12-16-10, 12:11 PM   #13
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dougmc, That is why I suggested a shop that deals with RC cars specifically.
The local shops don't specialize in anything -- they have cars, planes, etc. Some are national chains (a franchise, to be precise), some are run by individuals. None of them really deal with building your own packs.

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I know that now-a-days it might be harder to find a shop like that with our national chains and margins being what they are.
Well, we are talking about now-a-days, aren't we? And R/C car racing has changed lately as well -- the old "six cell NiCd with can motor" has largely given way to Lipo and brushless, hasn't it? Lipos are a bit harder to make packs for, I just don't think it's done like it used to be.

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Heat shrink tubing isn't something that will stretch and work, If it doesn't fit, don't force it.
Oh, it absolutely is. If your tube is too thin to fit around your wire, you stretch it out a bit with a hemostat and then it'll fit. You can't stretch them too much, but yes, you can stretch them out with no problems. Of course, you'll have to find a better way to stretch something bigger -- a hemostat won't work.

OK, let's do the math here.

$0.79 for the shrink wrap itself.
Their cheapest shipping option for this to my house? $8.53.

So we're looking at $9 to fix a $4 battery. Granted, you'll have the materials to fix more batteries than just one, but you won't have to do this repair very often. At least the link I gave only wanted $3 shipping.

If this is a one time thing, just use some electrical tape, and super glue it to itself and the existing heat shrink rather than relying on it's own stickiness. If that's too thick to fit in, then just replace the battery.
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Old 12-16-10, 12:46 PM   #14
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Feel better now?

Smile man...I didn't mean anything.
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Old 12-16-10, 01:22 PM   #15
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Smile man...I didn't mean anything.
I didn't see anything to be offended about, if that's what you mean. I just disagreed ...

The idea is good, it's just that ordering shrink tubing just for this isn't cost effective. (Which is sad, really -- throw away a battery just because some plastic like stuff broke, and tape won't stick too effectively? But I think electrical tape with super glue will do it.)
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Old 12-16-10, 02:38 PM   #16
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I had the wrap begin to peel on a brand new 18650 and nothing worked well to fix it. Some thin electrical tape and section of shrink wrap all made the diameter too large - it would slide in but not out. It might work in a device with different tolerances, but none I have. Super glue might have worked but the piece has since torn off.

The Batteryspace shrink wrap is meant for packs and so is thicker than that used on cells, so aside from the cost it remains a roll of the dice whether it would also make the diameter hard to work with.

Unless they are nice AWs or some mid range cell, they really arent worth messing with unless you have some of the stuff on hand to try.
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Old 12-16-10, 07:41 PM   #17
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Unless I can get it directly from a supplier. I'm close to St. Louis. Maybe I can find some there. Or maybe Radio Shack can order me some.
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