I have a 6yo laptop whose battery died within the first six months. I have been using on ac power since then. I read an article about repairing the battery by disassembling it and replacing the individual batteries which make up the laptop battery. I managed to pry the top off the battery and there are 8 3.7 volt cells inside (see picture). I check on the cost to replace the cells and it is reasonable seeing that I can no longer find a battery for the Toshiba. I also found a very sophisticated circuit boare in the battery (see picture). My question is, how do I know whether or not the circuit board is functional and what the heck is it supposed to do??

there are pictures at misterfixit.com/Toshiba

Message from this car mechanic's web page

I find it stange that you can't find a new battery for your old Toshiba. As usually most do exist somewhere. But if you have tried, that's that then.

Yes I'm aware that you can replace these internal cells yourself (as dangerous as it is)
I suppose try (at your peril) to see if the new batteries fix it. The internal board can be faulty too, but usually not. You might want to attach a clear small pic.

the pictures are there . . I had forgotten to add the .htaccess to the folder which resulted in the "forbidden" message . . sorry about that . . . Bob

The board looks ok (but it could still be faulty, ie they are usually double layered)

The circuit board regulates how the cells work for both the process of discharging and recharging. More here: http://www.priorityelectronics.com/batteries-howtheywork.htm

You could try to replace the batteries and hope for the best

What I was looking for was someone who knows about the circuit board and possible test points on it so that I could rule it out as the cause of the failure. Then I would be able to replace the cells with confidence. I have found a battery made by BTI Part number: TS-1100L that claims to be the replacement for my battery which sells for 129 plus s&h so I have an option - but being a tinkerer I want to know what the failure mode of this battery is so I am leaning towards replacing the 8 cells for between 40 and 60 dollars.