[pjphilli (Peter)]

Hi

I have a Canon 400D with a battery pack type NB-2LH.
The battery has three terminals. The outer ones are marked +ve and -ve
and the normal about 8 volts appear across these. However, there is a third (middle) terminal which appears to be at the same potential as the -ve terminal. What is the function of this middle terminal? I suspect it is a battery charge sensing function that the camera recognises.

The reason I am asking is that I have a 240 power pack which is specific for the Canon 400D and which delivers the required approx 8 volts to the + and - terminals as above. I have checked that this is so when the power supply plug is inserted in the back of the section which slides into the Canon like an ordinary battery. I have ensured that the power supply plug sits fully in when the insert is in the camera. However, the camera does not switch on. I notice, however, that bench tests show that the middle terminal of the slide in section is open circuit (ie no connection with the -ve terminal as per the normal battery). Is this my problem?

Cheers Peter