Insight into the inside of the hearing aid

@BeLo said:

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

So funny you mention this. If I wind up returning my M50 for battery replacement (unlikely since I haven’t for so long) I will mark the internal frame in some manner to hopefully answer that question. I think @tenkan noted he was an engineer and suspected the battery can be swapped. He is probably correct. At some point they will be doing battery swaps and the actual hearing aid model will have long been out of production.

@BeLo That leads us to your expertise. Knowing that they need a battery that will be off-the-shelf years after the hearing aid model production has ceased would lead me to believe they have used something they suspect will be available. Any thoughts on how we could match measurement data from @sterei scans to readily available batteries ?

You could just look at the serial number in Phonak Target and see if you get back the same serial number.

@RCF said:

your comment about the “two little nubbins” had me thinking at first you meant the two little spots no the clear case.

Oh Yeah; I see your two nubbins now. I don’t know what to think about those?? Might be to use a tiny spanner to rotate the case counter clockwise a little in order to dislodge the case from my two nubbins and then easily remove the case. But I’m just guessing?

@RCF said:

I’d love to see more data and a viewer. Assuming you can rotate image in the viewer

Yes, you can rotate and cut to see inside. PM sent.

@pvc said:

I see your two nubbins now

I think these “nubbins” two are marks from the injecting tool’s pusher. These are pins used to push the part out of the mold after the plastic part was injected.

@RCF said:

@BeLo Any thoughts on how we could match measurement data from @sterei scans to readily available batteries ?

Unless the pictures are misleading it looks to me like a metal button cell inside a plastic housing.
It also looks possibly spot welded directly to the enameled wire leading to the rest of the device.

I’m intrigued that it appears to be in a metal casing as this reduces the charge available for the given volume of cell so there must be some beneficial trade off, probably safety but maybe something else

I’ve had a look around based on those measurements and a couple of things struck me:

1. There are readily available (RS Components) Lithium based rechargeable button cells, I couldn’t immediately find any matching our criteria but since they exist and are manufactured in quantity it wouldn’t be too difficult for Phonak to have them custom made.
2. It looks like a tight, if not impossible, fit, but there is a battery called a 400909 that might be a suitable replacement. Lithium cells are a bit ‘squidgy’ so it might work, example: Pardon our interruption...28

It’s more than likely that there’s a Chinese website out there with the exact replacement part but it will take a bit more digging.

Wonderful post.
I have Paradise Audeo P90R’s. It’s good to see what is inside.
And now I understand how to charge my batteries…the routine is important. I won’t run them dry.

Thanks for your post.

DaveL

@BeLo said:

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!

Thanks so much for your information. I’ve had to reset my hearing aids twice. Taking them out of the recharger, the light was solid green An hour or so later one hearing aid was dead. I had to reset the hearing aid and charge it fully to use it. I wish I had 312’s, but the rechargeable hearing aids are great otherwise. (I have a workman’s comp claim for hearing loss due to noise).
DaveL

I have Phonak M50R. One of the batteries is dead after less than 2 years of use. Since I got the pair on Ebay, nobody want to repair it locally. Hence, I would be very happy if you could share info on how to open it to eventually replace the battery.

Many thanks

@bradw said:

rinsing with something…perhaps alcohol?
etc?

Alcohol damages the casings of the hearing aids so likely the same with Mic ports etc as well.

I’m an engineer too, and once worked at a lighting control company. One thing we did was to test wall plates with Formula 409 (not sure it’s available outside the US). It’s a popular cleaner, but it seems 409 includes some chemical that is particularly hard on plastics, so stay away from it. I’d use mild soap or diluted dishwashing detergent.

Well that’s depressing.

Yes very good pictures, yeah it’d be good to ID those batteries.

Can you tell if the battery wires actually pass through the circuit board or if they are just soldered on to the top?

From the photos and the size of the globs of solder it looks to me like it’s just manually soldered to the top of the board on both sides. It would just be a case of de-soldering and then reapplying a conformal coating when soldering in a replacement.

My unreliable audi recently told me that the actual hardware cost of an HA was $100, if remotely true then the battery replacement procedure would need to be pretty straightforward to be economically logical.
Maybe more than just the battery is swapped out for the in-house replacement procedure to make it easier for a technician?

There’s text visible under the plastic, so looking hopeful.

Yeah but it’s pretty hard to make out with that plastic cover, plus I don’t think the wire would be going right through, it would be lazer soldered in some way to the battery.