Not OP, but i remember having a camera that use AAs and would not support rechargeable. While it powered up, it would not take photos and instead shutdown. I think they used to be able to deliver less power, also when i put them in the gameboy the little led was a tad dimmer that non rechargeable one even when fully charged
Most of the old rechargeable aa or aaa batteries were NiCd, which would be 1.2V vs the 1.5 you get from alkaline. I believe the voltage drops off more slowly than alkaline, but since the starting voltage is lower some devices just can't handle it.
We had a set of cb radios when I was a kid, they had 12 aa battery spaces but two "blanks" installed. You used the blanks and 10 batteries for alkaline, but removed the blanks and installed 12 if using rechargeable to bring the voltage to an acceptable level.
