I’ve been reading the Oticon Real miniRITE manual
which covers rechargeable and disposable battery models. It’s interesting to see differences which go beyond the logistics of supplying power to the instrument. The following comments apply directly only to Oticon Real miniRITE, but AFAIK technology is similar throughout the industry.
Temperature (pages 73-74):
Minimum operating temperature of rechargeable is 41°F vs. 34°F for disposable. Yes, aids can be protected from the cold with a hat or whatever, but 41°F is balmy for some places, and an extra margin of 7°F isn’t negligible.
Minimum transportation temperature of rechargeable is -4°F vs. -13°F for disposable. Extra margin of 9°F.
Maximum storage temperature of rechargeable is 86°F vs. 140°F for disposable. Big difference, and the limit for rechargeable could have implications for storing a set of spare aids even at home.
Explosive atmosphere (page 63): The explosive atmosphere warning applies only to rechargeable, the opposite of what I would have guessed. Irrelevant for most people, but really important for a few.
Water and dust resistance (page 72): Both are rated IP68. Disposables do require extra action if they come into contact with water, namely wiping off inside of battery drawer and leaving it open for half an hour before installing a new battery. Arguably a slight advantage for rechargeables, but not nearly as much as been speculated on this forum.