How to replace battery in Phonak Audeo M-50R

[gtremblay]

Here is what I did to replace dead batteries in my Phonak Audeo M-50.

I would first suggest to read this thread: Insight into the inside of the hearing aid. It contains a lot of usefull infos and photos

Strategy used: remove te dead battery from its plastic casing, slide a new one in place and
reconnect the 2 wires to the main circuit

Parts used:

1- Battery from this supplier:
https://www.alibaba.com/product-detail/M7854S1-ICR7854-LIR7854-3-7V-25mAh_1600227890083.html

2- Electrically conductive glue/paint. It is more paint than glue (low viscosity) but it works

https://www.amazon.ca/Conductive-Electrically-Adhesives-Conduction-Connectors/dp/B09KVK5NB3?psc=1

Steps for the battery replacement:

1- Remove the receiver

2-Open the external enveloppe and remove the first half

3- Remove the second half

4- Using the heated metal tube, remove the flat battery casing sides. To disconnect the wires from the battery, I used a thin knife inserted between the wire and the battery.

5- Remove the battery from its casing noting its polarity

6- Insert the new battery in the casing with the correct polarity in the right place. It is critical. Be sure that the end of the wire is bare (no isolation)

7- Glue the first wire on the new battery and let the glue dry for a couple of hours. Repeat for the second side.

8- Place the HA in an owen at temp. 50-55 deg C for 24 hours. Note the glue will be conductive only when completely dry

9- Re-assemble and place in the charger until the green light stays on. Be sure that the charging contacts protrude enough for charging

Results:

Both HA work now as new.

When used for 15 hours in a quiet surrounding and connected to phone (left side) but no streaming, I get the following battery level:

Left 60% Right: 70%

So, repairing the first one is somewhat stressing but once the process is established it will be a lot easyer for the second one.

The device and parts are very tiny. Work slowly and take a lot of reminder photos.

Note the piece of wood and the rubber band that I used to hold the device when necessary.

Feel free to ask questions.

I hope many will successfully do it! Let me know…

Happy new year!

See the photos below

[tenkan]

Fantastic, always good to see a successful DIY project, this will help a few out for sure!

[pvc]

Congratulations on your success. Whew, that took some doing. Yes, I have some questions if you don’t mind.

1. Did you remove the wires first, before using the heated metal tube to remove the flat battery casing sides?
2. When using a thin knife inserted between the wire and the battery, does it remove the entire length of wire? Or does it cut the end of the wire leaving a small portion of wire still attached to the old battery?
3. Does the replacement battery fight tightly into plastic casing or is it loose? Did you use the conductive glue/paint to also hold the battery tightly in the plastic casing? See red arrows in the image below.
4. Any thoughts as to whether the procedure could be repeated in a few years after the replacement batteries wear out?
5. Did you oven-cure both sides together or cure one side and then cure the other side?
   
   

[dankailo]

“That’s one small step for a man, one giant leap for mankind.” - Neil Armstrong!

Amazing & Superb!

HAPPY NEW YEAR!

[Markismus]

Great! Just the Christmas present that I would’ve wanted to wish for.
25mAh: That’s about half of what I estimated. How is the performance? Can you stream for 2 hours and still wear them for 16h or more?

[gtremblay]

1- You have to remove the battery sides first since the wire are inside (partly) the casing

2- At first I tried to unsolder the wire with a soldering iron but without success. I believe that the entire wire is removed carefully with the knife. Didn’t really checked since the remaining wire part was long enough to be glued to the new battery.

3- Yes, the new battery fits tightly and there is no need to glue it in the casing. Your red arrows show a non intentional glue overspill. I used a bit too much…

4- The procedure will be easyly repeated in the future. I will eventually do that

5- I applyed glue on the first side and cured it for a couple of hours. Repeat for the second side. Then cured both sides together for 24 hours. Too much curing? I don’t know. There is no instruction with the glue package. The only info is on the amazon web page

Bad news

My trashcan is very sad because it didn’t receive a fancy HA for Christmass!

[gtremblay]

Many thanks for the good words. But I am not a Superman! I am just an old fart (75 YO) enjoying to tinker and play with everything not working as it should…

You too can do it.

[gtremblay]

25 mAh seem to be typical for this size of battery (li-ion). The performance so far is similar to new HA. Since I never do streaming, I can’t answer your question. I will make a test…

[Zebras]

@gtremblay

Didn’t really checked since the remaining wire part was long enough to be glued to the new battery.

Would this wire eventually be too short the more you replace the batteries?

[sterei]

@gtremblay
Couldn’t the wires be replaced? It looks like beeing soldered to the pcb.

[gtremblay]

I don’t believe so. For th next replacement, the wires will be easy to unglue to the battery. The glue strenght is not very high.

[gtremblay]

Yes they could be replaced but the solder is covered with conformal coating. It shoud be removed before trying to unsolder. This is well above my soldering skill due to the tinyess of the device. Actually, I don’t see a need for replacement.

[ffraley]

Was the oven curing necessary, or just for convenience? I don’t see anything on it in the Amazon listing

Fred

[gtremblay]

On the webpage scroll down until you see this:

Step 3 specify heat application with a heat gun at 100. I assume it is deg C… I don’t have a heat gun and I assumed that a lower temp. for a longer time would be preferable. I don’t really know how long it is necessary. And I was not in a hurry…

[ffraley]

I ordered this one, it specifies hair dryer 5-10 minutes.

1*Solderless Silver Conductive Wire Paste Glue - PCB Electronics Repair Tool...

I think I’ll cut a shield from something to cover everything except the battery, don’t want to risk loosening other connections. My oven won’t go that low if F,

Waiting for a response from China on the batteries. Is there a simple way to order from Alibaba? Thinking I’ll order 10 due to shipping. I have one pair with a bad battery to experiment on. If it works I’ll keep a spare pair and still have a few batteries and a couple of extra glues left over if someone wants to buy them from me.

[Markismus]

I was chatting with the customer support about the cells and he asked which option I wanted.
I thought that you used the single cell. However, Why didn’t you choose the cell+wire option?

[gtremblay]

Good find for the glue. Since I am in Canada, there might be custom fee and delay.

You can apply a small drop of glue precisely where needed on the battery after positionning the wire. So no risk of problem there.

For ordering, the procedure is about the same as Aliexpress. I paid with Paypal. Good idea to order 10 if needed. Note that they prefer to ship to a company (instead to an individual).

Go for it. It will work!

[gtremblay]

Since I decided to keep the old wire and glue it to the new battery, no need for a battery with wire. Moreover, I believe it is the only one model not encased in plastic casing. If that is right, you would then have to remove it from its casing to insert it in the existing casing.

[ffraley]

Alibaba-
Batteries-$3
Courier - $55

Aliexpress-
I see no listings for that size battery
I get no hits from US companies when I search for . I have not tried contacting individual companies

Markismus - was Shenzhen Coincell Battery Co., Ltd. your source? Wide open to other sources.

[Markismus]

@ffraley

Markismus - was Shenzhen Coincell Battery Co., Ltd. your source? Wide open to other sources.

Haven’t found any other sources, yet. Seems to be the only company so far. Still, the rechargeable cells for 1.5V were more than 50€ before, so it comes down to the same. Only now I’ll have looooads of spares.
I do wonder whether it’s feasible to make them swap-able again. I really hate it that the cells die early in the evening after listening to music for a few hours. Would be great to walk around with multiple charged cells and be free to stream my head off. That would finally make rechargeable HA an improvement over the ComPilot. ( I don’t really remember whether you could recharge it whilst listening to music, but I definitely recharged it while doing something without music.)