Re-celling battery packs

A search of the forums reveals just a little discussion here and there about re-celling the battery packs of various H/PCs, but no thorough discussion. I'd like to hear people's experiences - good and bad - with re-celling battery packs. This can be helpful in two ways: 1) by giving users here a general idea which packs can be rebuilt successfully; and 2) giving those with the right tools and skills how-to guides for rebuilding specific packs.

The idea for this thread came from my own experiences attempting to rebuild a few packs. After successfully rebuilding a dead pack for my Hitachi ePlate (which uses four 14650 cells in two-by-two configuration), I've had less luck with LG Phenom Express and NEC 900 packs, both of which use the more common 18650 cells. I'm getting better at soldering connections, and was able to solder the cells' tabs successfully to the packs' PCBs (much more difficult in the case of the Phenom, where the PCB runs the length of and is affixed to the three cells, which are connected in series). But so far the 900 pack and the two Phenom packs are all running down within 30 seconds. I'm hoping that they just need to be recalibrated, but since neither device has a battery calibration utility, is there a faster and more reliable way to fully discharge the batteries than just letting them sit in the device (which may take days)?

(BTW, I've also tried re-celling the dead pack in a Sharp Mobilon Pro PV-5000 that I recently picked up - again three 18650s in series - but so far it doesn't even seem to be taking a charge. )

Edited by CE Geek 2009-07-04 1:17 AM

I've recelled about 30 Book Digital G138's with 2100 and 2600 mAh 18650's. The process was fairly painless, although getting the tabs to connect safely to the charge circuit was a little fiddly as the CC is rather long. In the end I used a little wire to extend the length of the tabs and make the circuit cleaner.

General Tips:
- Do not attempt to replace NiMh or NiCad with Li - Just DON'T
- Invest in low heat, low toxin solder - you don't want any unexpected reactions from the stuff you found in your garage draw
- Some sort of padded vice - be VERY gentle - to hold the cells still is better than your hand (or someone elses)
- If you're using Li Cells always ensure that you're reinstalling the charge circuit correctly - take photo's of the thing from difference angles before you start
- Li + Heat from soldering iron = bang. Do not take risks with Li cells and bad soldering iron control
- Get some heat shrink wrap to finish off your new battery package
- Once you're done, prime the battery. don't try and use the device. Charge it then fully discharge it, then fully charge it. You can now use the device. In my experiences, the charge circuit will not have a clue what it is doing until after a second full discharge (but you can use it). After this second discharge standard Li best practice applies - see the CESD on battery use best practice

I have recently rebuilt 900c battery pack sipped with two 18650 Li battery.
It was quite simple. You have just to pay attention of battery directions and circuit soldering (heat on Li battery is dangerous). after rebuilding I have full charged the pack and the used it untill discharged completely. It did work an still does perfectly.
There is a detailed guide on Rich's site on how to rebuld NEC 900c battery pack.

Now, I am looking for an how to guide on rebuilding Sigmarion III battery pack.

I just found a nice tutorial for the Netbook here: http://linux-7110.sourceforge.net/howtos/netbook_new/LIbattery/LIbattery.html
My question - is the battery in the Netbook Pro the same?

my experiences were OK in the past.

jornada 7xx batteries mainly. also smartbook and a JVC MPC33.

all 18650's, I didn't do the rebuilds myself, but afaik they went OK without any special problems. Rich's guide would be good enough

slycarter: sigmarion 3 needs 18500's iirc. matrixcore knows more

Edited by cmonex 2009-09-09 7:49 PM

I'm sure many of you know of dealextreme, but I figured this would be a good place to indicate that they sell 18650/18500 (and many other formats) batteries with free shipping from Hong Kong (though it sometimes takes a while). I have a couple of question though - should I go for the "protected" or "unprotected" battery? Are they the same size?

Here's a link to their battery section: http://www.dealextreme.com/products.dx/category.400

Edited by jigab00 2009-09-10 5:19 PM

Ok n/m I figured out the difference between protected/unprotected (protected has small undercharge/overcharge/over-discharge circuit breaker under the negative cap). However, it adds a little length to the battery, and thus will make it a little tighter than the original. Impossible to say if it's a go or no go without trying, I guess.
Also, Ultrafire has a new "3000 mAh" 18650 (it's been tested to ~ 26-2700 mAh) which is a slightly bigger (both circumference and length) - so be careful as it might not fit your original battery pack.