Can anyone tell me what the extra contacts are used for on flat pack lithium-ion batteries? I'm trying to jury rig a charger for a spare battery for my iPAQ. The charger works fine on a similar 3.6 volt lithium battery from an old cellphone, but does nothing when connected to the iPAQ battery in the same way - directly to the plus and minus tabs.
I'm guessing that the additional two tabs on the battery are involved in the charging process in some way.