I'm trying to replace the AAA batteries that came with my BT cordless phone, as they are terrible quality and have quickly degraded (they now only last about 20 minutes after full charge). They are 1.2V Ni-Mh, 550mAh, and similar to these.
I have some good Duracell AAA rechargeables, also 1.2V Ni-Mh, 750mAh. My question is, why don't these work as a replacement? Putting these into the phone does not give power to the phone, whereas swapping them out with the old batteries turns the phone on straight away.
As far as I can see there are no listed properties of the batteries that differ apart from the mAh, and I know enough about electronics to know that it shouldn't make a bit of difference to compatibility.
Is there some unlisted property of batteries that is causing this?