Short battery life on A620

Hi, I have a Canon A620 since april and it works fine, but in the last weeks I noticed that batteries lasts for a few shots only. I'm using 4 Sanyo NI-MH 2700 rechargeable batteries.

Last week I was able to take only 50 shots (all with flash) until the camera says "low battery" and turn it off automatically. I tested the batteries at that moment and they had 1.3 volt (2) and 1.1 volt (other 2).

Is this normal? I read that this camera can take much more pics with one charge. Is this a camera problem or a battery problem or a charger problem? How can I test them?

Thank you all.
Christian