Hearing Aid Performance as Battery Runs Down

I’ve been told that digital hearing aids do not perform at full capacity (using throw away batteries) toward the end of battery life. Now back when I wore Starkey analog HA’s that didn’t seem to be a problem, since my Starkey aids seem to function fine up until battery died. Several years ago when I switched to Widex I did notice a decline in HA performance during the last few hours - or even day before my size 13 or 675 batteries failed. On the plus side (at least with the Widex aid) I always received a “warning tone” an hour or so before my battery died.

In any case I was wondering if rechargeable batteries also have an impact on HA’s, when they approach the end of their charge. So if a battery charge lasts say 18 hours, could a HA user notice a decline in HA performance when battery reaches 16, 17, or 18 hours of use? I’ve also read on HT that “heat” can impact the life of a battery and for users who live in warm weather, battery life (or should I say strength) will decline faster in warm weather than cooler weather.

Putting aside the pluses and minuses of rechargeable battery versus throw away, is it true then a person using rechargeable batteries will see a decline in HA performance every evening as their battery weakens, where someone using a throwaway battery will just notice power decline once a week, or longer if bigger battery is used?

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Both Zinc Air batteries and LiOn have a similar discharge curve. Both hold their native voltage until very close to the end of life, or charge, and then the voltage drops quickly. Both Zinc Air and LiOn will maintain native voltage through about 85~90% of it’s life or charge cycle. So it all depends on how much energy is being taken from your batteries during the day. LiOn hearing aid batteries are designed to last a day on a charge, but both will exhibit the same end of life, end of charge, characteristics as they drop below their native voltage.

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In other words don’t think of batteries in a flashlight where the light gets dimmer as the batteries get older. Hearing aid batteries hold their charge until they die. Otherwise we’d be putting in new batteries everyday.


I wear Oticon S1 and S3 using Costco batteries. I usually need to replace the battery in my weak ear after about 6 days. There are times when after 4 or 5 days, I notice a decline in clarity. When that happens, I just throw out the weak battery. Of course, since I change as pairs, that means sacrificing a possibly good battery.

Since the difference in the life of the battery in the better ear typically only lasts about 10-12 hours more, I change both at the first sign of decline. If I wasn’t so disorganized, I would swap L and R daily. That way they should die together.

With Costco batteries being so cheap and my HAs efficiency, I consider it money well spent to not have to ask others to repeat themselves just because my batteries are weak.

I also notice sound quality declining when nearing the end of the battery life. Depending upon my hearing needs, I will also change batteries early. Streaming also stops at a low - not dead - battery. I try to be proactive because I hate the inconvenience of dead batteries.

@MartinGale and @Mago what name brand batteries do you use?
The Power 1 batteries I use do not show weak signs until dead.

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I also use power 1 batteries and I never notice any weak signs until dead either.

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I use Duracell and Power One. Streaming stops at 20% (?) regardless of brand of battery (Oticon OPN1).

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Yes except for the streaming from the TV connect for me

Are you getting 20% off of an app?They are not known to be reliable.
If you are noticing a failure of sound, ok.

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I use disposables (Rayovac). Consistently get 9 days out of both sides. Stream telephone calls 5 out of 7 days at work for ~7 hours.

I use the batteries until the bitter end. The low battery chimes sounds half an hour before or so. When they turn off, I open and close the battery door and get another 5 or 10 mins before the battery is truly depleted.

Haven’t noticed any difference in performance at all with a new vs old battery. Sometimes change batteries mid-telephone call. Takes seconds to do.

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I use Rayocacs or Power One, and most of the time they are good right until they die, but once in a while I will think I am having a bad hearing day then the batteries die completely and I put in fresh ones and realize the problem wasn’t me.

It isn’t consistent and won’t happen with every battery in a given package, and I have never even paid enough attention to say whether it happened in both ears simultaneously (my aids have been close enough that I have always changed both batteries when one died).

I just always assumed that every now and then a less then perfect battery got out in the wild.

“Are you getting 20% off of an app?They are not known to be reliable.
If you are noticing a failure of sound, ok.”

The 20% will be on the iPhone. I agree it is not reliable, but it is the best we have - an estimate only. If I am streaming TV, I wait until it no longer streams to change batteries. If I am going to be on phone calls, I will change early. One aid not streaming prevents both from streaming. I have worn hearing aids 20+ years; changing batteries and keeping track of usage to avoid dead battery at an inopportune time, is a way of life for me (and so many others). That is why I was so disappointed in the colossal ZPower Rechargeable Failure. I am just really happy I could go back to disposables and my routine.

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@Mago sorry to hear about your Zpower issues.
Are those the batteries that can be replaced with regular zinc batteries?

I use Ray-O-Vac batteries and have also noticed that streaming tends to get wonky near end of life.

Just from reading replies I feel its might be best to replace (throw away batteries) four to six hours before they expire - if you want full HA functions. Of course there is no timer on a HA to tell you exactly when a HA will fail other than a warning tone/notice at the very, very end of battery life.

I’m also assuming with recharge batteries (which I have never used) it might be best to “recharge” an hour or so before batteries are fully drained. Of course no one likes to reduce battery operation time on a rechargeable, but I’d rather have an aid fully function-able (with fresh battery replacement) then wear and not hear as well due to reduced battery power.

ZPower Rechargeable Batteries can be replaced with disposable batteries. Thank Goodness! Because ZPower just simple DID NOT WORK as they were supposed to, I was never able to get an assessment, feel, or routine as to when they would fail-shutdown-or sound degrade. My experience was erratic, unreliable, and there was no way to work around it. Ultimately, I had my Audi change the drawers / doors back to the original and I only use disposable now. Battery life immediately improved over using disposables with the retrofitted ZPower doors.
I also want a fully functioning hearing aid. I keep track of exactly when I change batteries, so I know when I need to put in new batteries. Streaming does reduce the battery life,as does noisy situations, but I have a pretty consistent average day schedule. And I do pay attention to what it says on my iPhone battery % even though it is an estimate.

This paper page 3 graphs zinc-air battery life versus temperature. If you get much below freezing, or above body temperature, battery life is significantly less.

However most of us wear the battery ON (or in) the body. Even a 1960 under-blouse body-aid will be near body temperature, not room or wind temperature.

My over-ear location seems to be 34C, in-ear a bit warmer, so about 80% of what it would be in a cool room. This weekend, if I let the aid dangle in sub-freezing air, it could go to 50%; but my ear would break-off (I’ll wear many head-layers).

At least with my modest aid, I have very little interest in battery life. I should get a week, and batts are cheaper than a dollar. $30/year is VERY inexpensive for the benefit.