@zimon
Interesting point - honestly, I have no idea if pascal's law is also applicable to voltage and batteries. Honestly, even if You're right, i would hesitate to connect different batteries, due to different internal resistance - as daniel_m said - and overall, subtle differences in chemistry (even if battery is of same type).

Following Your logic, it would be like measuring drop of two different types of water - one very "hard", and one distiled. flow won't be identical.

Still, i'mwaiting eagerly for dr_frost_dk's results, as real life can be different, from both Your (i.e. water comparison not applicable) or mine (differences too small, to impact real-life usage) theories.

@stlpaul, awazix, thanks a lot, will investigate those.

/Estel