I have a feeling that most laptops use NiCd battery packs, or at least those I have seen did. You probably don't need to balance NiCd packs, or it does not make that big difference as it does in lithium batteries, where unbalanced pack can lead to big fire easily.
NiCD batteries in laptops ... what, 10 years ago?
I'm pretty certain that laptops use Li ion or Lipo batteries.
till today they are still using 18650s 3s2p arrangement with individual discharging leads at least for a 7.4V system with about 4AH, not sure about the larger packs but probably 6.2AH if they are not cheaping out and making the user pay a bomb for cheap chinese cells (The ones i have came out of a ACER laptop ala 2006, a single core AMD Turion 64 MT-40 Acer laptop that was smashed ... don't ask why)
I'm pretty certain that laptops use Li ion or Lipo batteries.
Oh well, forgot that LiIon sometimes look like NiCd cells.
That's a grevious mistake ...
Here is a picture of the guts of my Acer 14.8 V 4800 mAh battery pack (Model P/N AS07B42) that came with my Aspire 5920G 5 years ago. I cracked it apart last week to replace the 8 18650 Li-Ion cells (4S2P, I guess). The cells are connected as shown on picture with main voltage tap at CL1 and CL5. In addition there are connections to PCB inside battery labeled CL2, CL3 and CL4 as well. The connector to the laptops has 7 pins. There are 2 temp sensors connected to two of the rightmost cells in the photo.
The 18650's I ordered claim to be 4250mAh. Yeah right! If that was correct my battery pack would increase in capacity from 4800mAh to 8500mAh
That would be a 77% increase. I just hope I didn't waste $32.
http://www.ebay.com/itm/350546818332What does the following text on the battery pack mean: "
Never attempt to disassemble or reassemble"?!?
EDIT: Original cells are SONY US18650GR (2400mAh)