Insight into the inside of the hearing aid

Are you curious what it looks like inside our hearing aids?
I certainly am!
That’s why I want to collect pictures and other information in this thread that will give us insight into the inner workings.
Some members have also ventured into repairs and can give tips on that. Or are looking for a way to replace the rechargeable battery.
Discussions are welcome!

Some time ago I was able to do an XRay CT scan of one of my Paradise P90R.
Many don’t know that CT technology is also standard in technical fields. It allows you to see and measure components that are no longer accessible. Be it in quality control or for troubleshooting.

I would like to open this thread with some pictures of it.

If anyone is interested in the data from the P90R, I can send a link via PM.
There is also a viewer for the data.
(about 3.5Gb total, Win64, and min. 2Gb RAM recommended).





Thanks! Very interesting. I’m impressed with what a larger portion the battery takes up.


Definitely I’m interested, PM sent.

It looks like a size 13 at that.

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Very Interesting. Looks like size 13 battery but thinner. Send me your link. I used to work in quality control.

The diameter is about 8mm:

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Definitely the same diameter as a size 13, what’s the thickness, about 10.5mm?

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No, about 5.3mm

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Ok that’s not good, so a custom battery size, different voltage and just half the thickness, be interesting what’s available on the market.

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Not interested. At my age I’m too busy watching the grass grow. I also don’t screw with my aids. I know how that will end…


Don’t know where you’re getting 10.5 mm from (that would be thicker than the diameter) This says 5.4 mm which is is pretty close to the measured 5.32mm. Hearing aid battery types and sizes


Yeah my bad, 5mm (5.10mm) is what I meant.
So looks like we could find something aftermarket then.

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@sterei what’s that voltage again?

Sorry, I can’t measure the voltage with CT :rofl:
I think it was @RCF , @pvc , or @BeLo who mentioned the voltage in an earlier thread?

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Ha ha yeah now that would be interesting! but you could run your voltmeter across the pins on a full charge, I might have a look at the F.C.CID website.

Edit, checked and found it, it’s 3.7v

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The link below seems to have all of the relevant info about the voltages that one should expect.
It doesn’t mention low voltage cutoffs as that isn’t part of the battery chemistry but in my experience they are around 2.7V.

To be clear there are normally two cut-offs when working with Lithium rechargeables.
The first cutoff is commonly set in software or a management chip and can be as high as 3.6V, this is basically when your device will display 0% charge and turn off.
The second cutoff is normally circuitry attached to the cell itself and is a fail-safe these are normally around 2.7V.
This is why a device left at 0% for a few days will be fine recharging but a device left at 0% for a few weeks won’t as it can self discharge below the second cut-off.

The other voltage to know about not mentioned yet is the storage voltage, this is commonly 3.8-3.7V and is the voltage that Lithium batteries like to be stored at to prevent long term damage.

Most instruction manuals that I’ve ever read say to long-term store your device at full charge, however if you have a quick look at any reference book about lithium rechargeables they all say never to store at 100%…
Personally I always follow the latter advice and not the poorly translated nonsense found in most manuals!


This doesn’t show on the CT scan. But it shows in the @RCF pictures.

Any guesses about what function is performed by the two little nubbins on the battery case? See red arrows. They seem to connect with the structure that holds the two (+ -) metal contact points for charging. Do the nubbins provide support for the (contact points) structure?



ETA: Maybe the nubbins are non conductive and designed to keep the contact pin apparatus from touching the battery case, as in this CT scan image;


I wasn’t able to measure the voltage because the battery was encased and the wires were lacquer coated. So without being somewhat destructive I wasn’t able to get a voltage on the actual battery. Where did you find 3.7v for the battery ? That is good information.

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I think I need to open them again and get more images. But your comment about the “two little nubbins” had me thinking at first you meant the two little spots no the clear case. No that I look at those they could be remnant from manufacturing but they almost look like they are inviting some type of spanner. Perhaps that clear cover pops off with the right tiny little spanner.

They were not conductive, from memory. But @pvc I think you have a good eye and that these are worth closer evaluation. Clearly designed with intent. But the purpose ? Hmmm ….

These are a amazing ! I’d love to see more data and a viewer. Assuming you can rotate image in the viewer ? Your images, at least my lay interpretation, suggest the charge nubs do none contact the batter cell directly.Perhaps the plastic casing gets removed and single solder points on each side as I think @pvc suggested in a different thread. I have a Marvel series but they look quite similar. I am happy to take mine apart again and take more images. Just need to find some time in coming week.

It has to be assumed that these are serviceable by a trained engineer without too much fuss or time/cost incurred, unless… (conspiratorial music plays)

Has anyone had a rechargeable battery replacement done and verified that they received their original HA back not a replacement new device or refurb?

It’s not that I don’t trust the manufacturers but…

Please forgive me if this is an unbelievably stupid question and mods please delete if so!