The Z-Power battery used in Unitron & Starkey devices among others should be changed once a year.
If you have forgotten to charge them one advantage is that you can change them for regular zinc-air batteries.
The lithium-ion battery used by Phonak should last according to Phonak 4 years before your notice any reduction in performance. If you have elected to go for a 5 year warranty the batteries could then be swapped as a repair under warranty. So not as easy to change as the silver-zinc batteries, but a less frequent change & no annual cost to change them.
To add to the previous replies, Starkey uses a silver-zinc battery that gives you 24 hours of power on a 4 hour charge and will last about one year. One benefit to this silver-zinc battery is that you can easily swap it out with a regular disposable zinc-air battery if you ever forget to charge it. Signia (Siemens changed names) and Phonak both have rechargeable batteries that also run for 24 hours on a 4 hour charge but will last about 3 years. These both use lithium batteries that are built into the hearing aid permanently so there is no swapping out the battery if you haven't charged the device.
I tend to prefer the flexibility of Starkey's silver-zinc solution, and I also like that it is a much smaller battery and therefore a smaller hearing aid than both Phonak and Signia's. I hope that helps!
I've been using rechargeable batteries for several years for patients with dexterity issues. For the most part this has been very successful. I've found that in most cases the batteries must be changed about every year to 18 months. What happens is after multiple chargings, the battery tends to decrease in it's the ability to stay charged. This results in the hearing aids losing power prior to a full day's use. When this time period becomes unacceptable, it's time to replace the batteries. When using NiMh batteries, I always fit size 13 as that starts with about 22 hrs initially. 312 NiMh start with about 15 hrs initially therefore have to be replaced more frequently. Recently, there has been Lithium Ion 312 batteries released that have considerable longevity, lasting 30+ hours on a single charge and 18-24 months replacement cycles. So far, these newer batteries are performing nicely and I encourage anyone not wanting to change standard batteries to research this new technology.
There are a few answers to this question:
Standard Rechargeable batteries (Power One Brand) last 8-12 months, and hold a charge for about 12-14 hours
New rechargeables like the ones at Starkey and Siemens last about a year and hold a charge for about 18+ hours
Rechargeable batteries that are sealed like Phonak and Hansaton last for 3 years and hold a charge for about 24 hours.
Size 312 or size 13 rechargeable batteries are typically good for 350-400 charging cycles. Most people only charge them once a day, typically overnight, so the lifespan is approximately one year. Some people store the hearing aids in the charger during the day. if you run a second charging cycle that way you will effectively cut the life of the battery in half. The batteries tend to loss their capacity to hold a charge over time. Initially you should be able to run 12-14 hours with a 312 battery. As the battery ages that time decreases to the point you may only get 6-8 hours out of a single charge. The newest products on the market now have sealed rechargeable batteries that will run 24 hours or more on a single charge. Their life expectancy is 3-5 years. They can be replaced by the professional in the office at the point they no longer hold enough charge to operate all day.
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