It probably is true that the chips they’re using these days draw more power, intermittently or continuously, than available zinc-air batteries can supply.
But are there chip technologies available today with low enough power draw, perhaps at a higher cost? If not, will they be available in the near future? Will costs drop, and if so, when? Could higher per-chip costs be made to work with the economics of hearing aid production and distribution?
I think one would have to be in the chip business, or the hearing aid design and manufacturing business, to come up with a reliable and actionable answer to those questions. Technology moves very fast, and companies aren’t giving away their secrets online.
Power draw also depends on the firmware. Is hearing aid firmware as efficient as it could be? I’m led to this question by the user who reported here that his Phonak aids’ runtime was half as long when running a saved program. Are there other inefficiencies like that, that the manufacturers are throwing power at, rather than fixing the software (which can be very difficult)?
None of the manufacturers are willing to promise that, right? And we’ve seen reports here about aids coming back from service with batteries that don’t perform at the level of new batteries.
If the refurbish goes well then, yes, you get a few years extra life out of them. If you have money or benefits then you probably want a new pair anyway by then. But there are plenty of people with hearing loss and neither money nor benefits.