Disassembling laptop battery pack and replacing the ones inside

Hi, so I've got an HP dv9000 laptop. the battery pack is old and only lasts for about 20 minutes when fully charged so I wanted to replace the batteries inside it. So I took it apart. But now I don't know which batteries I should buy to replace the old ones. Do they have to have the same voltage when put together?

Here are my battery pack specs:
Product number: hstnn-lb33;

8 batteries inside;
Li-ion batteries;
14.4 Volts, 63 Wh;
4400mAh;



The batteries in the pack are aligned after each other in a serial connection.

I would like batteries that last longer. Would that be indicated by the mAh or the Volt number?
I don't really know much about this.

Also I didn't really think about this before I took it apart. One side of the pack is open. It broke off when I opened the pack. I can't put it back. So is it dangerous to use the pack like this? The batteries are intact and the pack still fits in the laptop and works. Can Li-Ion batteries explode? If yes, are there other rechargeable batteries that I could put in there?

I got the idea to take the pack apart after watching this video.

I don't know if this was a good idea but I've got nothing to loose.
I didn't buy a knew one because they just don't last long enough even if they're new.

Thanks for replying,
Philip

 

The forum in the link below can give you a lot of information and help in getting replacement li-ion battery`s

Flashlight Electronics - Batteries Included - CandlePowerForums

 

They're all the same voltage, if you buy a li-ion battery cell, it WILL be the same voltage as any other li-ion cell. The figure you should be interested in is the mAh though, basically get the highest you can find/afford, this figure is how much charge the battery can take. I'm pretty sure the management chip shouldn't freak out if it has a higher than normal capacity.

 

any 18650 li-ion cells will be good enough. I would recommend protected 18650.
If you go on deal extreme.com . You can buy 6 of them for under 20 i believe.

 

Protected is not necessary since the circuitry in the laptop battery already has that covered.

 

I made the mistake of purchasing protected cells. They're bigger than the unprotected ones and didn't fit right.

 

Protected 18650 are exact same size as regular 18650 li-ion cells. "18650" is the physical size of the battery. It's like almost all AA batteries are the same size.

 

If you peel the plastic wrapper off the end of the cell, you can see and remove the protection circuit.

There are some cells labeled as 1865 that come a little longer than spec due to their protection circuit.

 

Yeah, protected 18650 are a little longer and slightly wider , the protection pcb is on the bottom of the negative end and there is a approx 4mm wide conductive strip running up to the positive end.

EDIT : a bit more information.

http://www.candlepowerforums.com/vb/showthread.php?t=277787

 

Be very careful, repacking a battery is dangerous. Your battery can catch fire and/or explode at anytime if its not done right. Lithium batteries pack a lot of juice! I've done this before and will only do it again if I have free cells. Because its cheaper to just buy a chinese battery off of ebay. Often the control board can be bad or corroded with battery acid or you touch something when soldering and boom! so proceed with great caution if you have never done this work before!!

 

The cells won't explode the minute you touch them with an iron, secondly they won't explode in the first place as they have a fail point in the casing which simply makes them go poof in a ball of flame. The tabs on the batteries are usually long enough that you shouldn't have to worry about the cells heating up.

 

Yeah, the batteries are supposed to be soldered together. They won't get hot during soldering unless you hold it on a lot longer than it needs to be.