The thing about a hearing aid is that it’s always on. That’s good! A hearing aid wouldn’t be much use to you if it switched off at random moments. Even when you’re at home and you’re engrossed in a quiet book, you need to be able to hear when someone knocks at the door or when your cat knocks over a glass in the kitchen (again). That kind of constant performance requires an equally constant amount of power.
Which means that if your hearing aid relies on single-use batteries, you might be replacing those suckers at a staggering rate. And if that’s the case, you might be tempted to switch to rechargeable batteries. But… should you?
Electricity Is Complicated
Let’s set the scene: You’re in the checkout lane at Target, looking at batteries (there are so many batteries… it’s overwhelming). And you notice a rechargeable battery in the same size that your hearing aid uses. The price is a little steep, but reasonable when you factor in all the single-use batteries you’ll save. So what’s the harm, right? So you make your purchase and try it out!
And that’s when your hearing aid completely shorts out. Maybe not all at once, of course. But once you put that rechargeable battery in, you might notice your hearing aid starts acting a little wonky.
That’s because the relationship between hearing aids and rechargeable batteries is anything but straightforward. The size of the battery is important, sure, but so is the composition. Because some batteries have a more potent charge than others–and the wrong charge can burn out circuit pathways in your hearing aid.
The Temptation of Rechargeable Hearing Aid Batteries
We definitely understand the temptation of rechargeable batteries. It’s not uncommon for some hearing aids to require a change of batteries once every week or so. And those expenses can add up. Rechargeable batteries come in two basic forms:
- Nickel-metal-hydride-battery (NiMH): These batteries work on a low enough charge to be compatible with your hearing aid. The only problem is that they aren’t terribly efficient. NiMH batteries tend to lose their charge faster and faster as you use them (it’s called “capacity fading”). So it won’t be long before these batteries become effectively useless.
- Silver-Zinc battery (Ag-Zn): A silver-zinc battery is a better all-around rechargeable battery. But unless your hearing aid was built specifically for Ag-Zn batteries, do not use Ag-Zn batteries. They run too hot and they’ll overload your hearing aid (it won’t explode or anything, probably, it’ll just stop working).
If you really feel inconvenienced by having to swap out your hearing aid batteries, you have unfortunately few options. But there are hearing aids available that are natively rechargeable.
A Li-ion Comes Roaring In
Lithium-ion batteries have been the gold standard for rechargeable batteries for years. These days, Lithium-ion (Li-ion) batteries even power airliners. So why has it taken so long to see these easily rechargeable batteries show up in your hearing aids?
Some of the problems have to do with how much current is going through a single circuit pathway at any given moment. Getting Lithium-ion batteries to go low and slow enough to work for hearing aids without producing too much excess heat has always been a challenge.
These days, though, it’s not uncommon to see Lithium-ion batteries running a set of fully rechargeable hearing aids. In these cases, the batteries are usually embedded within the hearing aid and not intended to be regularly replaced. Just make sure to leave your hearing aids on the charger when you go to sleep at night and you’ll be able to go a long time without having to worry about your hearing aid batteries.
The Ability to Stop Thinking About Your Hearing Aid Batteries
Because that’s what we’re really after with rechargeable batteries. It’s nice to be able to stop thinking about your hearing aid. To not have to worry that your batteries will cut out at an important moment and leave you disoriented (or missing out).
But hearing aids are intricate pieces of technology. If your hearing aid was not designed with rechargeable batteries in mind, it’s generally a good idea to stick to single-use power sources. But over time, hearing aids with Lithium-ion batteries may start to displace their non-rechargeable counterparts.
Which means a rechargeable hearing aid battery might be in your future a little sooner than you thought.