I read up on the 312 size Power One Accu plus NiMH batteries and it says the following:
Power One Accu plus Nickel Metal Hydride Rechargeable Hearing Aid Batteries Size P312, 1.2V 22mAh, 2 batteries. Made in Germany. Requires PowerOne brand Accu charger also available from Microbattery.com Disclaimer - Due to the limited mAhcapacity of NiMH rechargeable button cells, this rechargeable battery may not besuitable for high power demanding hearing aids. If your zinc airbattery lasts less than 5 days, the NiMH Accu rechargeable battery on afull charge will likely not last through an entire day’s use and it notrecommended for your hearing aid). THIS ITEM IS NOT REFUNDABLE. UPC# 4043752145557
So I think it’s not going to work for my HA which typically lasts me only about 4 days due to direct streaming.
Another way to look at it. The zinc-air battery is 180mAh capacity while the NiMH above is only 22mAh capacity, or 1/8 less. So if my zinc-air lasts only 4 days, the NiMH one will last me only 1/2 day, not even one full day. Not worth the trouble changing out and recharging 8 times more often.
Another way to look at it. It costs me about $32/year to buy zinc-air batteries for my HAs from Costco. The NiMH set will cost me $28 and will probably also last me a year (assuming 1/2 day charge so 365x2 = 730 cycles which is about the life of a NiMH under 1000 cycles). So from the cost perspective, the saving is negligible for the 8x frequency hassle incurred. This is not even factoring in the cost of the actual charger itself, which is $85 and we don’t know how long its own rechargeable battery will last? Maybe 3 year?