Hi,
Do not assume something isnt working properly just because you dont know the inner workings..
You need to calibrate your battery indicator. Go to the OSD parameters menu, choose the "Battery" submenu and enable "Show battery volts" (In my opinion thats better anyway).
Now you can read directly what voltages your batterys have when they are freshly charged, or near empty, and set those in the MAX and MIN voltage fields. I have an SX100, use NiMH batterys as well, and i have set 2550 mV for MAX and 2250 for MIN. You could use those values, i guess.
Then theres the culprit with NiMH batterys - they dont have a linear discharge curve. Meaning, freshly charged NiMH batterys have around 1,4V, which will drop quickly to 1,2V when its used. It will stay at 1,2V most of the time until its empty, at which point the voltage will drop again quickly. This cannot be displayed in percentage properly.
Rising voltages are normal as well. When a battery is under load (e.g. charging flash) the voltage will drop a little, due to the power drain. After returning to idle, the camera drains less power, the batterys do kind of "recover". Explaining that would be a little out of proportion here, i guess.. Its normal, so dont worry.
Last question: Additional features do consume a negligible amount of additional power, around 2-5mAh more. Dont worry about that either.
Regards.
