Batteries in dryer?

I have a Phonak D-Dry dryer that I use in summer when I need to dry my HAs. They’re not super wet but I want to look after them nonetheless when moisture is high. My HAs are CICs with size 10 batteries. The Phonak manual says remove the batteries from the HAs when putting them in the dryer. I have heard a few people don’t remove batteries when putting HAs in a dryer. Any views on this? I would have thought if the drying temp is ok for the HA then it is ok for the battery? Or is it the UV-C cycle that is the issue? I’d prefer not to keep removing the batteries if possible.

I’ve figured that the extra wear and tear by opening the battery door all the way is not worth it for removing the batteries.

I go away a lot with work and use a D Dry. I use a Dry and Store when I’m at home as I like the longer operating time.

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I leave my 312 batteries in the aids and just open the door a bit when I put them in my desiccant dryer. I get about 5.5 days from each set.

I do the same with others above. I open the battery doors a bit to turn the HAs off, and leave them over night in the Dry & Store. I get 10 days to 2 weeks from 675 batteries.

You have to be careful I have found that if I do not open the battery doors all the way the batteries are still making contact with my ITE hearing aids. I do leave the batteries in the aids while in the dryer but I make sure the battery doors a completely open.

I concur with cvkemp. Some of the dryer suppliers have also decided it is not necessary to remove zinc air batteries. Obviously, you cannot remove the rechargeable Li ion. I also open the door slightly to disconnect the battery. No problem.

I think if you don’t at least open the doors, the batteries will wear out sooner.

I don’t know exactly how zinc-air batteries work, but for lead-acid, carbon-zinc, alkaline, lithium ion and any other battery or cell I know about, leaving them on and working will drain them faster.

A couple of hearing aids ago, I did an experiment. I put the tab back on one battery at night and not the other. The battery with the tab lasted longer.

Then I put in new batteries and switched the ear that I put the tab on overnight. That battery lasted longer, so it wasn’t a right vs. left aid thing.

How much longer? Back then I was using Resounds that lasted about 10 days. I got an extra day out of it. Not significant but not insignificant either.

Over the course of a year that’s a few batteries and packaging not going into the landfill.


Over the years of using Dry & Store and now the Costco dryer, I have never removed the battery. I was told I did not have to and it makes sense. The batteries are powered by the chemical interaction with air. With the battery doors open there is nothing draining the batteries. Putting the tabs back on makes no difference as they have already been triggered by air and have air in them already. There is no switch turning the batteries ON or OFF. But the open doors keep the aids from draining them by usage.

For a desiccant dryer I can see it would not matter. For a ‘heater’ dryer (usually running on USB) I suspect the heating temp is minimal. I am not sure of the temp in my D-Dry but when I open it I can just feel a very mild warmth come from the chamber. I might try and measure it. But I would be surprised if it is above 45c. Either way it doesn’t seem hot or damaging. Based on the above comments I’ll give it a go with batteries in and doors open.

I use a Phonak charger every night for the rechargeable batteries so does this dry the aids as well? I was told to leave them in there overnight.

This is what I’m talking about. A purpose built dryer and UV steriliser. Just there simply to remove condensation in the HA. Particularly for my CICs where they sit completely right inside my ear. On a hot day sweat and humidity can build up inside the devices.

I’m not sure if the charger has that feature.

The Costco dryer is outlet plugin, not usb. It is more powerful that the old Dry & Store I used to use. My HIS suggested it as the D & S stopped doing the trick. This one runs only 30 minutes and leaves the aids warm and dry. It has solved moisture problems I was having with my previous aids. I do not take the batteries out. Air activates them, not uses their energy. Only the closed doors and connected contacts use power. I’ve been using Costco batteries, though in the past I swore by Power One from Germany. Initially mercury free didn’t generate enough power for streaming aids. They have been fixed now though and work quite well with power hungry streaming aids.

You can leave batteries in dryer with no damage to batteries. You might lose a very limited amount of battery life due to dryer heat exposure but its relatively insignificant. I leave mine in every night, but I do open HA battery compartment when drying aids out.

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It’s not the heat exposure, it’s the drying effect.

Zinc-air batteries use a wet electrolyte that’s involved in the chemical reaction. See the Wikipedia page below. In a nutshell, if you dry them, they will fail sooner because they lose the water in the electrolyte which is chemically involved in the reaction, although it is conserved in the reaction. It is removed by drying.

" During discharge, a mass of zinc particles forms a porous anode, which is saturated with an electrolyte. Oxygen from the air reacts at the cathode and forms hydroxyl ions which migrate into the zinc paste and form zincate (Zn(OH)2−4), releasing electrons to travel to the cathode. The zincate decays into zinc oxide and water returns to the electrolyte. The water and hydroxyl from the anode are recycled at the cathode, so the water is not consumed. The reactions produce a theoretical 1.65 volts, but this is reduced to 1.35–1.4 V in available cells."

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I use a heat / uv dryer branded Phonak. I open the battery doors just as I would at night anyway. They go in the dryer which runs at low heat for 3 hours. The battery life is not affected compared to the dessicant dryer I previously used. BTW, that trick of taking the tabs off the battery for 5 or more minutes before they go in the hearing aid seems to maximise life. There must be some activation process that benefits from time before current drain begins.

Be it heat or drying effect, it all plays a minimal role on decreasing the life span of a HA battery. I do agree its best to take batteries out when drying aids. But if one leaves them in dryer, night in - night out it’s not the end of the world. From my experience you might lose an hour or two on throw away batteries over the life span of the battery. Basing that statement on size 312, 13 and 675 batteries. Smaller batteries might be impacted more by aid dryers.


Damn it… this is not what I wanted to hear. :sob::sob::sob:

According to that then, desiccant dryers are probably even worse for zinc air batteries than the powered heat dryer?

I use size 10 batteries.

Further quote from the article: 'The operating life of a zinc–air cell is a critical function of its interaction with its environment. The electrolyte loses water more rapidly in conditions of high temperature and low humidity. ’

Well I’ve had more then one Audi tell me leaving batteries in dryers does no damage at all, except slightly reducing battery life. Personally I don’t like touching batteries a lot, so I just leave them in at night when drying aids. But as I said earlier, you do need to open battery compartment flap to properly let HA’s breath. A lot of older folks who know longer have the hand coordination they used to have, are better off leaving batteries in HA, when drying.

Now I can’t speak for rechargeable batteries but we all know rechargeable batteries can’t go in a dryer. Of shall we say why would someone want to spend hours recharging their rechargeable battery to then spend hours drying their rechargeable battery? And don’t be fooled. Desiccant tabs are not the proper way to dry a HA with moisture issues.

Here is a somewhat dated article that claims based on Eveready Energizer studies, zinc air batteries will last 10-20% longer if put in a dryer at night. Moisture is said to be detrimental to the life of the battery.

To Dry or Not to Dry?


Which fits that hearing aids die from sweat. They don’t die, the batteries do. Put fresh dry batteries in and you are back in business. When I was racing my dog I was sweating profusely, and going through batteries like crazy. The moisture blocks the air from getting into those tiny vent holes … dead battery.

I think there is a reason that they call them zinc air not zinc water

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