View source for File talk:Battery T40 Series 3rd-party.jpg

The 28-pin chip is an InterSil X3101V28, which is supposed to take care of three cells only according to the datasheet :-)  I would not use this battery pack at all, it looks like the 3rd-party making it is cutting corners dangerously :-p.  Unfortunately, the really interesting chip is the other one, whose markings are illegible.   Hmm, I wonder if this thing really is 100% compatible with the original battery packs?