Shrink wrapping salvaged batteries

Batteries and Chargers Rechargeable Batteries
1

The process is new to me; just wanted to share.

In the picture, 18650 cells from left to right:

- Newly re-wrapped

- Ready to wrap - (with insulator temporarily in place)

- Cell inserted into wrap

- Bare cell (Sony IMR)

Note the marks on the + button are light sanding marks from removing the tabs and solder used in the oem pack. The bare cells were pulled from a Dyson pack which were so heavily glued it became easier to remove the old shrink wrap (lowest voltage was 3.96v which charged to 4.2v). The cells are very easily grounded/shorted in their bare condition, so they were carefully stored until the replacement wrap arrived.

Sourced the shrink wrap (0.25mm flat, or both sides combined) sold by the meter from Fastech

Process:

- Cut wrap to 70 mm lengths ($0.06 each @14 lengths + small scrap from a meter) using a Fiskars cutting board my wife keeps for hobby use

- Placed battery so that top would insulate and not cover the + pole

- Used hair dryer/blower to start shrinking at the top where it folds over

- Pushed battery out of tube, added (salvaged) insulator, put back in tube

- Finished top of battery, moved to bottom, finished body last

- Easy to fix your own [or make fakes |( ]

- After wrapping I use a permanent marker to label the + and - ends, add the date, a unique code for the cell, the initial voltage before charging, and also transcribe info printed on the cell (material I used in not very translucent)

Summary:

Much easier to do than I expected. After I found that I didn’t need to hold or fix the insulators it was - literally - a breeze. Finished cells compress to a hair under 65 mm and are ~18.15 mm in diameter with the material used.

70 mm worked perfect for these Sony IMRs - the bare batteries have a slight indentation where the wrapper goes over the edge (almost like a shallow negative button). With some of my pulls the bottom is completely flush and the wrapper is flush with the bottom and it does not wrap over the edge onto the bottom like I did these.

I’ll only use these in single cell lights with springs, so the over-wrap on both ends should help prevent accidental grounding and not create a problem. Otherwise, they might need a magnet between cells.

EDIT: The material is very slick inside, at least before heat is applied. I had thought it might be sticky or gummy and hard to slip the batteries in and out . . . but not at all.

2

I use a lighter to shrink them.
Wrap needs really just a gentle touch with flame, far less than shrinkable cable tube.

3

Nice work on the wrapping! For anyone doing this, be extremely careful. If you set them down positive side down with the wrap off that could easily short them out.

4

Nice job. You make it sound easy.

5

Thanks!

Everybody doing pulls that has or might nick a wrapper on a cell should keep some on hand because it is so easy. The 6 that I did so far were perfect.

Even if I were to screw one up, what an inexpensive mistake that would be so easy to fix! I feel a lot better about these than the ones I’ve used packing tape on. Those will soon get new skin, too.

As posted above by Cheap Thrills, it is just a light touch of heat vs the normal shrink wrap used for wiring. The hair dryer works surprisingly fast on the ends. I always melt stuff when using a flame, so I’d never even try that with the blow dryer working so well. Really wouldn’t recommend a heat gun just to keep the heat off the battery as much as possible.

As long as the price per meter stays fair at Fastech I’ll just add a more to future orders so that we both save on postage. I haven’t looked around there or anywhere else, but I’m wondering if there are good protection circuits to add to pulls, especially if it was just as easy to do before wrapping?

6

Adding protection circuits is not that easy. To do it right requires that they be welded to the cells.

7

Sounds like another challenge and torture test for Scaru! J)

Since the pulls are already tabbed, I’m thinking the risk is lessened versus direct solder to terminals.

http://www.lygte-info.dk/info/battery%20protection%20UK.html

Won’t be using that DX circuit . . . others?

8

nice job on the re-wraps, they look very professional. I’ve used PCBs from DX in several builds, although off the top of my head none of them have drawn more than 1A. I have one coming for a pack to drive a friend’s XM-L@3A light that I made for him, we’ll see how that works.

TBH, I’ve never tripped one, so I couldn’t honestly tell you even if they work or not, so take the recommendation with a pinch of salt. I’ll be checking the short circuit protection on the one coming and I’ll have to get my friend to check the over discharge protection, although PCBs tend to trip way lower than I’m comfortable with (2.5 to 2.75V I think).

To add one to a cell, just tin the ends with solder. Tin the end of the short strip with solder and solder it to the cell so that the PCB folds back to show the plain bottom. Put a piece of electricians tape over the bottom of the cell and tape the PCB temporarily in place. Tape the long strip to the side of the cell to measure how long it needs to be. Cut, tin, solder. Remove temporary tape and do your wrapping magic. You’ll probably have to apply some pressure to the PCB while doing so, to make sure you don’t leave any compressible space between it and the cell.

9

Nice work! Thanks for doing the measuring for me; I already had a roll of the FastTech Shrink Wrap ordered to do just this. I have several laptop-salvage cells that had the wrap nicked, and I've had to repair those with kapton tape in the past.

@ Mattthemuppet:

I've tried ordering the protection circuits from DX recently and they were unable to ship them; after waiting a very long time, I finally cancelled the order. If you've had success ordering them recently, let me know so I can order some for my cells...

10

last one I ordered was 5 days ago and it says “full shipment”, whatever that means in DX speak. I’ll have to check again in a week. Last one before that was a few months ago, I think.

11

Looks like you have the shrink tube down. I have been using the stuff from an ebay seller. Don’t know how it compares with the fasttech shrink tube. The ebay stuff is clear so you can see the original manufacturer label after you’re done.

After wrestling with goo-covered pack pulls for quite some time, I stumbled across two aids in removing just about any gooey glue used. Sometimes if it is a light sticky tacky glue, I’ll use isopropyl alcohol. That seems to clean most of it off although it may lighten the manufacturer specks printed on the original battery label.

But the REAL trick for getting all kinds of messy hardened glue off the batteries? (especially the caulk-like white stuff.) A small piece of wood with reasonably sharp edges.

I use a SQUARE chopstick with sharp wood corners. I have NO idea how this works and stumbled on it in a fit of anger: “How do I get this *&^%$# stuff off!”

Rub the glue vigorously with the edge of the chop stick and it curls or just falls off. You’re not scraping it off really. You’re just rubbing it HARD with the wood edge.

How does it work? Breaking the surface tension? Cracking the glue? Got me. But it works. I know it sounds crazy. And it doesn’t hurt the most fragile original battery wrappers. Yes, it does take a little work, but nowhere near as much as you would think. I have used this trick on probably 50-75 pack pulls at this point and it works great!

12

I had the most trouble with the hard black RTV-type of adhesive used on some of the older Dell packs I've taken apart. I ended up having to carefully shave the glue from the pack with an exacto knife. Difficult to do without nicking the original shrink wrap...

13

>>>>>hard black RTV-type of adhesive used on some of the older Dell packs I

Try a sharpish square corner on a small piece of wood. Takes that black stuff right off. Or it has for me. Once again, you’re not scraping with the wood. Just rubbing, pretty hard. It curls up in little flakes and falls off. I know it sounds like witchcraft, but it works.

Don’t expect it to just fall off in a sheet after you touch it with the wood edge. You DO have to rub it fairly hard.

Good luck!

14

The packs I’ve opened normally have a form of the sticky stuff or the black stuff. Just rubbing with my thumb has worked on almost all of them. The Dyson pack had something clear like an epoxy that dried very hard.

Thanks for the tip, I’ll give that a try on the two packs I’ll be working on next - a Dell with LGs (probably the sticky stuff) and a Compaq.

On the protection circuits, I’d really like one that cuts off at ~2.9 - 3.0v, or so. Would prefer not to go with 2.5v.

Oh, the Fasttech PVC is not solid, but it’s closer to solid than clear. I can read through it. It’s pretty similar to the blue LGs pulls.

15

>>>>> Just rubbing with my thumb has worked on almost all of them.

Yeah, that’s EXACTLY what made me try the piece of wood. My thumb didn’t have any skin left on it after getting the gummy goo off 30 of those suckers.

>>>>>Oh, the Fasttech PVC is not solid, but it’s closer to solid than clear.

This stuff is perfectly clear. Not fasttech speed in getting here from china but not too bad. Very thin but strong. Gone through three rolls already. Takes VERY little heat to shrink it, much less than shrink tube for wire insulation. Hairdryer would be fine. Might be too sensitive for an open flame. Looks PRO when done, like it was done in a factory, almost like there’s no extra layer there at all.

I sometimes make TINY TINY nicks in the manufacturer’s shrink wrap when wrestling cells outta packs, so I always shrink tube the pulls. But as someone pointed out, sometimes you can’t save the manufacturer’s shrink wrap. It gets too beat up in extraction. Then I just cover the silver cell.

Oh, btw, i put the pull info on the cell with a sharpie UNDER the clear stuff, so it’ll never rub off, like: HD, 1-2-13, 3.85 v. For Home Depot, found 1-2-13, 3.85 volts when pulled. Then i use a sharpie on the outside to write down charge dates and charge voltage. I let em sit for a while after 3-6 charges and see how well they held the charge. I’ve found that it can take 10-15 cycles before the cell stabilizes and really starts to hold a solid 4.2 volts. So few of the cells I find are truly bad, i wonder why people throw ’em out.

The panasonics and the pink samsungs and sometimes the green sonys are great. LG tans, gray and turquoise samsungs can be iffy, but the tan LGs can rival panasonics if you get a good batch. I rarely find the red sanyos people say they always find. I’ve had panasonic pack pulls hold 4.2 volts for MONTHS, which is better than some new panasonics I have bought from various online sources, so I wonder how “real” the real online panasonics really are.

I LOVE pack pulls. It’s like opening xmas gifts! Never know what you’ll get.

16

TBH you’ll have a hard time finding a PCB that cuts off that high, even the high quality ones in AW cells and the like cut at 2.75V. At the end of the day it’s just added insurance to prevent you completely trashing a cell as you should be able to tell when a cell is nearly completely discharged, at least in linear drivers. It’ll be a bit harder in multi series setups with buck drivers, although ideally those should have some kind of low voltage warning built into the drivers.

17

Requested better than the DX version at Fasttech. I could live with 2.75v as it’s not that far from ~2.9v. Don’t plan on running pulls in a multi-cell light, though I suppose I might try some good Sony IMRs once I’m set up to balance charge.

I’ve only ever tripped on the low side once as an accident, but that is what protection is for. Normally I won’t run lights till the battery dims or dies.

I’ve had an XML in a P60 light refuse to run high on a UF3000 for more than a minute, but that seems to be the driver and not the battery protection circuit. After several recharge cycles, the UF3000 does run the led on high in a different host - though at relatively low current compared to a KP3100.

18

>>>>>Normally I won’t run lights till the battery dims or dies.

Most lights on unprotected batteries are pretty darn dim (borderline unusable) by the time the battery hits 3 volts. Many of my lights lose high by that voltage or start blinking.

19

Thanks, for this thread.
I have the shrink on its way too. I have no naked Batteries, but sometimes I rip the wrap apart to see what’s underneath.

20

Yeah, I’m frequently recharging around 3.2v - 3.5v now that I have so many spares it’s just too easy to pop in a fresh cell and the attended recharges don’t take as long. I’ve done a few around 3.1v but that’s fairly rare - mostly with the LGs.

The only light I’ve run dead off alkalines is a SK68 clone on NiMHs. It dims somewhat and then dies. Lot shorter run time than I expected, but it’s pushing a bunch of current. I haven’t run my 3 mode version dead yet, so no idea of how long I’ll get with it on low.

Couple more salvaging first for me in this thread.