Battery question

Hi fellow babies!

I was wondering about the following... everyone here is saying laptop batteries have 18650's in them... well my batterie is currently dead (lasts about 15 minutes or so...)

Would it be possible to remove the 18650's, buy new ones and then put them in the batterie case? :d

somehting like this seems good..

anyone has any idea what the difference between dx 18650's and these ones are.? Because they look different..

(and no you fools i'm not talking about the color! :p )

Already made packs seems cheap enough not to mess with.

Agreed. Having taken apart more than a few packs I'll tell you it's not easy. It would involve carefully opening up the case (which is epoxied together), Removing the old cells (which are taped together inside), and soldering the tabs of the new cells correctly and trying to remember where all the balance charging connections need to be landed. In an emergency it can be done, or if you are unable to source a replacement battery. But to me it's just a big PITA with a lot of frustration and little to no cost savings.


You may be able to find someone in Belgium who rebuilds laptop battery packs. There are several in the UK. If you have a common laptop it may even be reasonably cheap.

You need specialised equipment to build the packs such as battery welders (Attempts to solder lithium ion cells are very unwise, even dangerous), access to the protection circuits used and so on. And there is no point unless you use good-quality cells, laptops are very, very hard on their cells. It is very unwise to try to do this yourself.

These days a lot of higher-end laptops use specially shaped lithium-polymer packs which are not repairable, just replaceable - in the case of Apple, with one that can only be replaced by the manufacturer.

I've taken apart 3 different laptop battery packs and the li-ion 18650 batteries were pink samsung's, blue lg's and red sanyo's. I tried to take them apart without breaking anything but it's imposible to do so. They are glued, taped and soldered together just like Match said but they use some super tough industrial strength/heavy duty glue and tape. J)

You're going to need like 8-10 18650s to make up the pack, it's rarely worth it to rip apart a pack to replace them unless you can:

1. Get them apart without destroying the batteries (which is difficult)

2. Be sure you're only replacing a few and not all of them (laptop batteries will generally trip a protection circuit if 1-2 fail)

3. Know which batteries you need to replace and can match the existing batteries in the case in terms of actual mAh rating and output voltage.

Otherwise, it's worth it to just get a new battery, unless you can find someone to rebuild it for you on the cheap.

I've actually had very good luck in that regard - I got one of those external laptop battery packs for $15 on sale, took it apart and managed to get 4 (out of 6) good, undestroyed IC protected 2400 mAh Samsungs out of the deal.


I've actually had very good luck in that regard - I got one of those external laptop battery packs for $15 on sale, took it apart and managed to get 4 (out of 6) good, undestroyed IC protected 2400 mAh Samsungs out of the deal.


I never thought about that as a source. I've got oodles of unprotected, but if those external packs actually have protected cells in em I'll have to keep an eye out for one.

This is the one I bought -

I'm not sure they're available any more as I got mine at a clearance store, but it did provide IC-protected cells.

Thank you for the link and confirmation on the cells, Jekostas!

4 of 6 good and protected? Lucky you.

Here's something kind of weird. Last August 8, 2010, when I opened up the battery pack that had 4 red Sanyo 18650’s in it, the first thing I did was to check the voltage. They were 1.45v, 1.45v, 1.48v and 1.42v which are very bad (from what I have read and learned) for li-ion batteries. I’ve also read that the best thing is to do is to get rid of them or recycle them because they are pretty much worthless.

So of course I went ahead and charged them all up. Undecided After a full charge they were all around 4.20v/4.21v which was cool but I figured they would lose their charge very quickly after a day or 2. I am glad to say that I was wrong. Smile Since then, I’ve checked and logged the voltages about once a month and today, after almost 5 months, the voltages are 4.14v, 4.15v, 4.15v, and 4.14v.

So what gives? Is this normal? Did I just get lucky?

Inquiring minds wanna know.