Good job, really interesting.
I’m not sure that’s the recommended Phonak procedure though!
This does make me wonder that they might be so cheap to physically manufacture as to be almost disposable. It just seems weird that it’s so hard to change a battery with no obvious easy way of doing so.
Thanks for your interest. I am happy if I can help.
I am sure there is NO RECOMMENDED PROCEDURE from Phonak. When Sonova repairs it under warranty it just sends a new one. Much sheaper. No needs to publish any info on battery or programming. It is a disposable product that you pay thousands of dollars and are not even officially allowed to program. When the battery dies out of warranty (when there is one) or any other problem you are dead!
Sonova: “Dear customer, we will be verry happy to send a new one for you. Just send us few more grands and bingo!”
We dont really own this HA. We are just allowed to use it and shutt our mouth!
It seems to be a very similar situation with other brands. Is it?
OK. OH! Wait. I forgot to have my morning coffee… 
Buy the way, I don’t anticipate to receive the new batteries (if ever) before several weeks…
While you are there, I am open to any suggestion. I am doing this “hacking” with the idea of making the new battery easily replacable. So I must avoid glueing or soldering as much as possible. Any idea?
Yes it is, for most brands. Demant (Oticon/Bernafon/Philips) has battery doors. The other manufacturer’s have built-in, non-replacable batteries without battery doors. You can see for yourself by simply looking at which hearing aids no longer have battery doors.
Though, replacing a lithium ion battery is not as simple as replacing a disposable zinc-air battery. There is a procedure that must be followed. Oticon’s fitting software Genie2 has instructions for replacing rechargeable batteries at the End Fitting step of Oticon’s Genie2 fitting software (and, selecting Batteries in the left pane). The instructions include “Reset battery statistics” in order to guarantee accurate daily usage beeps. At this time I won’t bore you with details about the battery replacement procedure, and also the details about lithium ion battery storage which also must follow a procedure if you are not using them daily.
Demant (Oticon/Bernafon/Philips) is the only Big-5 manufacturer to allow battery door access for replacing the rechargeable battery. A pin-tool can be used to open the battery door.
Here’s a picture and a video-link that shows how to open the battery door. Click this link; https://www.youtube.com/watch?v=Qx4NNE5BOwk
I’ve just taken apart a Phonak Marvel 90R which looks identical to the Marvel 50R photos above and I agree that it just doesn’t look to be (easily) serviceable at all.
I’m just going on my experience repairing the odd smartphone or tablet over the years and even those where space and weight are at an extreme premium are relatively easy to service if you have the right tools and know the correct procedure.
These things presumably can’t be submerged in solvent or the microphone(s) would get damaged and given the way the battery(cell) case is attached with globs of adhesive I can’t see any reliable or easily repeatable way of removing it apart from submersion in a solvent.
Clips are used to hold the case on and enable it to be changed and could have been used with the battery too but haven’t been. They are good enough for securing the main body of the device so could have been used.
It’s just weird, especially if other manufacturers make it straightforward to do. Maybe it’s all about the IP68 rating: if the battery is fully encased it’s unlikely to get wet? Then again I note that the Oticon Opn S mentioned above still has an IP68 rating.
Possibly it’s a trade off between easy serviceability and overall reliability: more returns but easily serviceable is more expensive for some companies than fewer returns but disposable devices?
In good news it does look possible that 400909 LiPo cells might actually fit as there is a bit of space between the cell case and the device but given how destructive removing the original cell looks I’m not sure if I want to attempt it until the battery is dead.
If you have access to both sides, how about a microdrill first, then tiny stainless wire through the hole, work it around like a saw. Maybe hot glue the aid to something first and hold the assembly in a vise.
It’s definitely possible to remove it’s just messy.
My comments were more about what the manufacturer’s procedure might be as I doubt a technician would be expected to perform an overly complicated or potentially destructive procedure.
Solvent is nasty to work with and heat would harm the battery so for me it’s a bit of a mystery what the official battery replacement procedure might be, if there is one.
Is it possible that the batterie’s plastic casing is also replaced together with the battery?
The manufacturer has the parts available, they cost nothing, so to speak.
That would mean further disassembly to remove the cover together with the battery. Would that be possible? Then just desolder the two connecting wires.
Yep, that’s my guess too. I think that the pin tool marks are evidence that the battery+casing were sealed together in a press, before installation. But that makes any DIY replacement effort worse.
We have enough problems just getting a new battery. Getting a new battery and a new case seems impossible. Getting a new battery plus case already sealed together, fuggedaboudit.
@gtremblay has successfully removed the cell and replacing it with another doesn’t look like a big deal, it just seems like quite a messy procedure, however it’s done, and not for the faint of heart.
Although maybe not a fair comparison both of the cheap aids that I disassembled had glue, quite a bit in fact, but it was quite tacky and easy to remove with just tweezers.
The glue in these Marvel devices appears on first inspection to be hard and almost glassy, it’s also indiscriminately applied between the rim of the battery and the chassis of the hearing aid. Whoever/whatever applied it certainly wasn’t doing so to enable easy removal.
Li-ion cells don’t even like temps over 40C so melting the glue seems unlikely as a standard removal method. Acetone would probably do the job but might well melt some other plastic components at the same time and would have to be applied carefully with a syringe. Solvent could be the ‘official’ way but it seems overly complicated when other manufacturers just have a door!
I think that you are correct and that the cell and casing are probably one part as far as Phonak are concerned. Going by the various manufacturer websites that I’ve looked at it is quite common to include some kind of casing or wire attachment as part of the fabrication process.
The soldering between the wires and the board of the device does look manual to me so again tallies with the theory that these are just glued in and then soldered before a conformal coating is applied.
I think that the 400909 LiPo will probably fit if the plastic cell casing was removed completely so that could be another option. I’ve grown more attached to my backup aids than I thought I would so I don’t want to go down too destructive a route at the moment but I’ll look out for a broken aid on eBay to experiment on.
@BeLo Your analysis is quite right. I believe there are only 2 options:
Option 1: Remove battery + casing. Due to the extensive glueing I believe that it is not possible without compromising the structure. Anyway, since the casing has a tab to lock the charging contacts firmly in place, it is most certainly proprietary to Phonak.
Option 2: Remove the battery while leaving the casing and wires in place and then slide in a new battery and reconnect the wires to the battery.
That is the option a selected. I still don’t know exactly how I will do it since I want the next replacement a lot easyer if possible. I will find a way…
Thanks to sterei for starting this tread.
Thanks to you @Belo for showing us how to open the enveloppe.
Enjoying this thread.
It sounds like the glue is a big problem.
If you threaded a screw into the battery.
Then carefully heated the screw to conduct heat to the battery which would heat the glue without heating the housing.
Then slide the battery out while hot using the screw to pull it out.
I don’t want to remove battery+casing. I already removed the battery from the casing and waiting to receive the batteries I ordered. See Option 2 above
Yes, I saw that.
I guess you could call my thoughts option #3.
Maybe
It is possible that the coin battery supplier completes the whole process of wrapping the battery with plastic and has 2 wires soldered onto the surface of the battery. The batteries are then sent to Phonak assembly plants. Just my guess!
My primary hearing aids are P90 Life, they don’t have the charging contacts, and have a significantly larger body than the normal P90s. I would be interested to see inside but they are quite new and I don’t want to take any chances.
It would be interesting to see why they are larger than the standard Paradise models and if it’s the same battery/cell in a plastic case design.
Unfortunately I don’t have access to a CT scanner!
@dankailo Yes, I think that it looks probable that the battery wires and casing are just one part. There doesn’t seem to be any easy way to open the battery case at all.
Inductive/Wireless charging in the Phonak P90 Life without the protruding metal contact (+/-) parts requires two coils;
I don’t know much about the size of the coil in the hearing aid? But if it’s anything like a hearing aid telecoil/t-coil, it’s typically big.
I’m looking forward to reading about your success when the new batteries come in. How much did you pay with shipping for how many?
Thanks,
Rob
@rob.frohne
Thanks for your interest. I ordered 6 units and paid $3US each+$55US for shipping (for 6 together). Note that I placed this order on Oct 19 and still no shipment…
I hope it is going to work.
This order is for samples. The seller accepted it but he said that they prefer to work with company… It may explain the “slow” shipment…
Lipo and li ion are not compatible. If the hearing aid discharges to 3v which is ok for li ion (factory cell), it would kill lipo battery in a few cycles.
I’m comfortable with that, it’s not the best thing for the cell but it’s far from catastrophic.
At that price I don’t mind running them down past 3.2v. I’d also have thought that software 0%, which I never reach anyway is probably well above 3.2v
3.2v to 3.0 is probably about 15mims usage so not a big deal.
They also have 10% extra capacity but will probably only charge to 4.1v.
I’ll be testing all of the voltages anyway.
