UK-NHS, Oticon Engage BTE. I’ve had them for 3 weeks, and today the battery levels on the app are L:60% and R:20%. I thought they connected to my phone independently but maybe only one talks to my phone. I changed both batteries about a week ago, turned them on/of at the same time. It was uneven when I changed them but I put it down to the night I didn’t open the battery door enough, I think it was a smaller difference too. They can’t stream so it’s not that. Might I be doing something wrong with them? I clean them every night with a mini isopropyl wipe before I put them back in their case, I have them connected to Oticon Companion so I can change the volume on my phone, and if they have a mute function in the volume control I haven’t found it yet (always struggled the hoover being loud, now I can turn my ears off).
Changed the right battery this morning (~3 hours ago), now the app is saying L: 10% & R: 70%. I have come to the conclusion that the app doesn’t know what the batteries are doing, and I’m not going to change them till they bleep and/or die.
Many battery chemistries result in voltage curves over the life of the battery that don’t reflect in a way that can easily determine remaining life. I’d suggest in these cases it is just a guess as to how much is left.
WH
I thought that you can only get battery remaining % status on rechargeable, I didn’t know you can get the status on hearing aids with disposable batteries.
My NHS Nathos Nova doesn’t show % on my phonak app.
Do you have unequal loss? If so, one aid will always use more battery life. Also, most aids use one as the “master” and one as the “slave” sometimes causing the master aid to have less battery life. And, did you check the staus when batteries were new to assure they both were at 100% to start?
I think it’s about the same. The lines on the chart look very similar. I ended up changing the left one a couple of hours after the right. I think the app just doesn’t know what it’s talking about.
I think OP said these are oticon aids, not phonak.
WH
Yes, that’s the explanation and you have found a good strategy to manage your batteries 
.
My new audi (very good) explained that with disposable HA batteries, it’s not possible to get a reliable measure (%) of remaining capacity.
Different for rechargeable HA batteries - with them you can get a fairly reliable approximate measure.