Why does hearing aid battery life vary?

Only eight weeks in, but one thing I don’t understand is why batteries last six days some times and five days other times. Use time is relatively equal. And my loss is more in my right ear but the left battery ALWAYS dies first – what’s up with that? (Laughing)

Please post your exact HA model and battery type.

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Even in the same package each battery can have a different capacity. That is very normal.


Oticon miniRITE Open dome
Oticon 312s that came with the HAs

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Batteries are so inexpensive (48 for $8 US) at Costco that it is not worth worrying about.

Oh I definitely am not worrying, as I noted I just don’t understand & find it curious.

Thanks all.

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As others have said, normal variability, including having one hearing aid always die first. IF that bugs you, you could go the hassle of switching batteries every day, but there’s no NEED to. Oh, and are you leaving them open to air for a bit before closing battery doors? This helps bring the voltage up. Considerable debate for how long. Some people ignore the recommendation completely. Others recommend 1 to 5 minutes, with more agreement around 1-2 minutes.

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Thanks for the note. Yup, have experimented switching batteries and I do let them air when installing new ones. It’s just curious.

Just had a thought. Maybe part of the difference is in the voltage detector (I presume that’s how the aids detect low batteries) I don’t what the voltage cutoff is, but let’s assume it’s 1.0 volt. If one hearing aid’s detector instead alarms at 1.01 volt, it would be quite likely that hearing aid would always run out first. Just hypothesizing. I could be full of it. ;>)

Groovy thought. Works for me. Thanks!!

Main differences are the input levels, application of gain and feedback manager performance - plus streaming.

Assuming most paired Aids draw similar power to function, most batteries will sit within a spec (although they vary a bit) the main differences are caused by the dynamic output of the aids. Let’s also assume that streaming functions are jointly biased and you have a equal loss on both ears.

One ear will be more vented than the other or the eardrum will be more compliant - so even on the same fitting prescription on each side - to achieve a balanced output, you’ll need more power or lose more power in terms of feedback management.


Related Question: A few times in the past year or so I will go for a walk after placing my hearing aids in a small case (with the battery doors closed). I’ll come back an hour later and my wife will say they’ve been squealing with feedback while I was away.
It’s logical to assume this drains batteries?

A-ha!! No doubt that’s IT!! You remind me that the ENT said I have weak ear canals that tend to collapse. The answer must be that one is weaker than the other. Woo-hoo. Thank you so much.

The will be variability due to usage of the HAs and also due to the batteries. A few days ago, I experienced a new battery failing after a few minutes.

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I wouldn’t say you’re “full of it” but I don’t think this is the issue. The precision of the voltage detector is probably around a hundredth of a volt as you surmise. But a hundredth of a volt is not going to make a big difference in when the end-of-life is detected. Do your 13-battery HA’s alarm when the power is low? Or do they just shut off?

Anyway, I side with darylm, that it has much more to do with variability of cell chemistry and secondarily to do with HA usage as far as the particular sounds it’s driving.

I use 312 batteries in my KS7s. They give me an intermittent warning tone when batteries are low. I either replace immediately, or crack battery door open if I can’t change then to disable tone.

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Interesting. With the KS8’s I get a lower frequency “I’m dying” buzzer like tone, and then after 10 minutes or so, a more normal tone, couple of beeps, and not long after that, they are done. My normal practice is to air up a replacement battery when I get the first buzzer tone. For the first time the other day I was streaming when the buzzer tone came in for one aid. The interesting part is that it quit streaming to that aid, but continued on with the other aid. It obviously goes into a power saving mode, before it finally dies.

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I find if I change programs frequently the batteries don’t last as long. And if one goes out I just replace both at the same time.

Thank you cjpines. I do replace both at once. There are instances when I change the volume level frequently if that counts. I don’t have what I think of as “programs”.

I ran a battery life test earlier this year on size 10 batteries for my CIC HAs. I use tiny CIC/IIC Signia Silk NX HAs (Specsavers version), form over function, so there is no BT, streaming, T-Coil etc. So this was just plain old HA life. No complexities.

I ran the batteries 24/7 to get a better whole life calculation rather starting and stopping and adding it all up. I swapped the batteries left to right about half way as I found the left always finished 10 or so hours earlier than the right.

This is what I found:

Rayovac Proline Advanced: 73.5 hours average (three tests all very similar results)
Power One: 71 hours average (three tests all very similar results)
Rayovac Extra Advanced: 70.25 hours average (three tests all very similar results)
Sivantos Extra Power: 69.2 hours average (three tests all very similar results)
Specsavers: 70 hours average (two tests all very similar results)

I believe the Specsavers brand is Sivantos as the pack is absolutely identical and both made in UK.

Note also, the ‘70 hours’ is absolute ‘power on’ battery door closed time.

I always air up for about 5-10 minutes.

My take on the results:

There is not a huge variation acoss all batteries when you run a more controlled start-to-finish test. Although these are all top end or brand name batteries. I pretty much got 70 hours across the board with a slightly better result for the Prolines. But the cost for me for the Prolines does not warrant buying them (mainly because they are not common in Aus). I can get Power One batteries far cheaper and they give solid results usually for me. Or Rayovac Extra Advanced. I pretty much always get 70 hours if I swap once about half way through the cycle. I always replace both together.

Of the occasional variation I have got in the past, it is usually down to one of the batteries completely failing very early on. Likely because the air seal sticker has not sealed so I has prematurely activated. My take on it.