I have a device that uses a pair of 1.2 volt NiMH rechargeable AAA batteries at 550 mAh (Philips HB550L).
Would it be harmful at all to replace these batteries with rechareable 1.2 volt AAA Duracells (or other brand) at 800 mAh or even 13000 mAh? Would it be safe, would it affect longevity of the device or batteries?
Are there other considerations when using higher amperage batteries?
The unit "mAh" is not amperage but is, instead, electric charge (the product of electric current and time).
Further, the product of the battery's voltage and the electric charge rating is the amount of energy the fully charged battery can (ideally) supply.
In short, using batteries with extra energy capacity will not harm your device, but would, instead, power the device for a longer time (all other considerations unchanged).
To avoid confusion, I would like to add to the first answer that the voltage of the new battery must be the same even though the capacity or amp hours can be increased. In other words, don't change out your nimh battery with a li-ion which could give you an even higher capacity, but at a much higher voltage.
Voltage must stay the same!
