Laptop 18650 battery question

[bthrel]

New member and one of my first posts.

I have searched to no avail for the information requested so here goes.

Yesterday I salvaged a laptop battery pack from a IBM T60, inside were six 18650's labled as follows in green shrink wrap:

SF US18650GR

T SA1130G18L


Following another great post on dissembling laptop battery packs I measures all cells with my Fluke DVM to be 3.84v, so they appear to be usable. I have a Ultra fire wf-139 charger and have read extensively the precautions one should take concerning these batteries. So, my question relates to the lack of shrink wrap on the bottom (- side ) of these batteries (cant post pics yet so I will try and be descriptive). Browsing through the many 18650 threads, it appears that all batteries I see have the shrink wrap overlaping the bottom, on mine there is essentially a ring of unexposed battery at the bottom as the wrap does not round the bottom edge and partialy cover the bottom of the battery. In this state will these be safe to use (wont short out) or should I cover them some how. I plan to use them in a JetBeam RRT-2 I have coming soon.


Thanks much

Brian

 

[bthrel]

P.S. I cant upload attachments as of yet so I cant post a picture, but I did find a post with batteries shrink wrapped similar to the ones I have..

Below should link to post 12 of the thread which has the picture. Although not the exact same battery, the shrink wrap on the green and purple batteries looks exactly the same, short on the minus end of the battery.

http://www.candlepowerforums.com/vb/showpost.php?p=3037299&postcount=12

So the question remains, are they safe to use wrapped like this, no chance of shorts?

Thanks for looking

Brian

 

[linterno]

Some of my Panasonic batteries removed from Laptop battery are the same. I Used masking tape to isolate it before using in flashlights.

 

[alpg88]

Some of my Panasonic batteries removed from Laptop battery are the same. I Used masking tape to isolate it before using in flashlights.

+1

 

[Conte]

If the inside of the battery tube is properly anodized, you should not have a problem provided it does not get worn off over time.

Otherwise, if you just hit it with some tape, preferably electrical tape, you should be good to go.

Otherwise, if you are up for some adventure, grab yourself a sleeve of heatshrink and re cover the cells.

 

[SilverFox]

Hello Brian,

Welcome to CPF.

The lack of shrink wrap at the bottom of the cell is normal for many brands of cells. In a multi cell application where the cells are in series, you may have to take additional measures to insure that they don't short out. This is not usually an issue with single cell applications.

Another option is to purchase some shrink wrap and re-wrap the cells.

Tom

 

[bthrel]

Thanks for all the replies and thanks for the welcome Tom.

CPF is truly a massive wealth of information.

I'll be using these solely in a JetBeam RRT-2 single cell application, but I think I will look into some shrink wrap. In the mean time I will use some tape slightly overlapping the bottom just to be safe.

Thanks again for all the info

Cheers :thanks:

Brian

 

[kramer5150]

Those green cells are Sonys. I recently pulled some from an IBM T61 pack . I tested them in my 6P-MCE which draws almost 3A with an IMR 18650. The green sonys delivered about 2.45A, so they are OK for any application that draws less than ~2A. They're certainly good enough for any decent ~1.5A XPE, XPG or XRE single cell light.

They have been sitting charged on my shelf for 4 weeks. I will test them for their LSD characteristics soon. I have found that a 4-5 week self discharge test to be a good way to weed out the under-performing laptop cells. Most hold voltage at ~4.12V over this time. The ones that dip down to 4.05V or less get tossed into my recycle bin. Note also that even the ones I toss are perfectly serviceable cells, they just need to be topped off more frequently.

Oh btw.... welcome to CPF!!

 

[etc]

Also got a bunch of these green sony laptop cells, and more.

Run nicely in my FiveMega 1x18650 body, with Malkoff M60L.

Used them in the recent power outage.

 

[bthrel]

Thanks all for the replies, ** Question answered ** :twothumbs

Have a great rest of the week and weekend

Brian

 

[casebomber]

Another option is to purchase some shrink wrap and re-wrap the cells.

Can you recommend a source/type of shrink tube? Seems like pvc is the way to go?
The normal shrink wrap (black rubbery) is much too thick to recover cells and I have checked all local sources to no avail...

 

[bshanahan14rulz]

Wow, sorry you folks only got sony 2200mAhs. I took apart a "9-cell" R61 battery, found 7 Sanyo 2600mAh cells. Jackpot! One was at 0.02V, it was obviously the one that killed the pack. I looked at the cell cycle counter and it said that it failed in just over 40 cycles. Double-jackpot!

 

[Wilmette]

Can you recommend a source/type of shrink tube? Seems like pvc is the way to go?
The normal shrink wrap (black rubbery) is much too thick to recover cells and I have checked all local sources to no avail...

Old thread, but in case anyone searches with the same question...

Load this into the search engine of your choice: ultra thin wall pvc heat shrink tubing

You're looking for 3 mil or 4 mil PVC (not polyolefin) layflat heat shrink tubing in 34mm width. There is a source, but they will make you buy a spool of 750' so I hope you're serious, as it will run (with shipping) well north of $100. Maybe several folks would want to pool their resources and share, as long as you can all agree on the color. They will not sell a partial roll or cut one for you. 34mm x 2 = 68mm. 68mm / 3.14 = 21.65mm diameter, more than enough for a nominal 18mm cell to fit. Bigger sizes will work, but the extra material has to go somewhere and my preference is to keep it to a minimum.

If you cut it exactly 1/4" longer than the cell, and center the cell so that there is 1/8" past each end, and shrink the tubing with the cell initially held vertically one end at a time over relatively low heat with a heat gun, I think you'll be happy with the overlap outcome. Finish the shrink by touching up the middle of the cell with low heat all around.

If you don't do the ends first as described, the shrink job will likely end up uneven.

* CAUTION * CAUTION * CAUTION *

If you cannot hold the cell comfortably in your hand while shrinking about 8 to 10 inches away from the end of the heat gun, YOU ARE USING TOO MUCH HEAT. 18650 cells should never, never, never be overheated ESPECIALLY when they are in your hand. This technique has been successful for me. I am not a battery expert by any means. There are a number of battery experts here on CPF and I hope one or more will chime in with any other cautions or details I've omitted.

Perform at your own risk. Getting injured is not economical or smart. Personally, I don't use unprotected 18650s in ANY multicell flashlight application. For those I have a nice supply of AW's fine cells.

As an aside, I found that an 18650 stripped of its factory heat shrink will fit in a paper dime roller with the length adjusted; the kind without the rolled lip. But I would consider that kind of an emergency work-around. I am not much interested in ending up with an unprotected cell bypassing the tailcap switch and destroying its charge capacity (or much worse) because I was trying to save a few cents.

 

[casebomber]

Wilmette, you pretty much rock, thank you. Sometimes it is not the cost savings we are looking for, but the ability, as I have some AWs as well and love them. Now can anyone tell me why a manufacturer would make a single cell 18650 light without a low voltage cutoff? I am perplexed by this...