I read these posts when my Oticon minirites started saying the batteries needed recharging a few hours before I would normally charge them before bed.
I presumed a battery would be simple and inexpensive to change. I was wrong on both accounts the batteries were very expensive and almost impossible to source without using a repairer with a standard service charge which was £150 per aid in the UK.
After confirming that I couldn’t find a source at a reasonable price for the Z22A or the original batteries, I started looking for other alternatives.
The original battery size fitted is 7.8mm x 4mm at 20mah which in battery terms is 7840 (CR7840 LIR7840) or other versions depending on the manufacturer.
The first source I found was on alibaba.com listed as M7840S1/LIR78403.7V 15mAh from the Shenzhen Coincell Battery Co. I was able to buy 6 of these directly for 83 USD. These were simple to fit and I calibrated them through NOAH (I’m not sure how this does anything or how in engineering terms it can do anything useful). However, it was soon clear that 15mah would not meet my needs as I got about 14 hours before the aids switched off (About 3 – 4 hours less than I needed)
After searching some more I found several sources on 1688.com listing 18mah batteries under LIR7840 and also LIR840 which is 0.2mm wider than the original size. I decided to go for the LIR840 for no particular reason except there were lots listed from one manufacturer called LIDEA and it was easier to find one that had a minimum order of 10 batteries. I had to use an agent to buy and ship them to the UK but the overall cost was about 30USD for the lot.
So far they seem to be working well after 15 hrs use they are showing about 40% power. Only been using them for a few weeks so I will have to see if they perform over time. I’ve got plenty of spares if they don’t.
I hope someone finds this of some use.