This is true of ANY battery. In colder temperatures chemical reactions slow down and all batteries depend on chemical reactions to supply power.
In point of fact lithium ion batteries should actually perform a bit better in cold than the zinc-air button batteries.
Jim
I can confirm that Oticon OPN S and More Lithium-Ion rechargeable batteries can be replaced in the office by the hearing care provider without sending the whole hearing aids in. Actually it just requires a little small pin head like that of a paper clip to open the battery door. Even the user can do it if they want (kinda like opening up the sim slot on an iPhone) if they have the right tool. But they still need to order the rechargeable batteries from the hearing care provider anyway. I don’t think the Oticon rechargeable Lithium-ion batteries are sold by third parties.
My VA Audi says that they can change the batteries in the clinic.
That’s a good selling point if it’s easy to replace. Even if it did have to be done in the factory, $200-300 isn’t terrible considering what the things cost in the place, so long as you get it back in a reasonable timeframe. I certainly don’t have a backup pair if they’re gone for 3 weeks. And as the average replacement, near as I have read, is about 5 years so if one change gets you through it certainly isn’t bad from that perspective.
@zuikoholic I agree it happens with all batteries. I expect it happens with Zn air but I don’t know that much about them to know how much shorter. My only point is that unlike a button battery you can swap out when it dies, a rechargeable Li doesn’t offer you that same ability. When it’s done it’s done until back on the recharger. Just like if you have to work long shifts you can run through a rechargeable and potentially be stuck.
How quickly do they recharge in? If you can throw it on a charger and get 80% in a short time it’s doable. Also, are there induction charging systems for these?
Any idea what price range is for audi to change one? (Or have there even been any out of warranty changes yet!)
It’s a bit of a mystery so far, maybe a member of this forum who’s an HCP can chime in.
But in this thread Oticon # 222 Li-Ion Battery for OPN S, @1628w9st said that he bought a pair of the replacement batteries from the HCP who sold him the OPN S for $40/pair.
3 hours to completely recharge the Paradise from 0. 30 minutes gives you up 6 hours of use. It does not take very long to charge them and get a substantial amount of time.
No induction charging on the Paradise. Induction charging is slower and research suggests that it shortens battery life.
Jim
Induction charging is only 60% to 70% efficient and generates more heat as a by-product. Charging by direct wire is 90% to 95% efficient, still generates heat but less so. Yet for my Galaxy Note 8 (and I think for my Samsung Galaxy Gear S3 Frontier watch), Samsung says that the heat generated during wireless charging “…does not affect the device’s lifespan or performance and is in the device’s normal range of operation.” (perhaps that’s because they expect you to buy a new device every few years?!).
I pop both my watch and my phone into the frig for 3.5 to 5 minutes depending on whether the room temperature is 60 deg F (winter) or 85 deg F (summer) before my 15% of full capacity or so charging stints just to cool the device down a bit before it starts heating up. If the device doesn’t have an internal temperature readout, I may occasionally use an “insta-read” infrared thermal gun thermometer to see what the surface temperature of a device is like. I don’t do any precooling for any hearing aid device as the battery is so small, the surface-to-volume ratio so large I am not worried about thermal buildup in charging any HA device or accessory.
Here’s some battery info on charging. There are some Li chemistry that have long lifespans but I think the kicker is that they don’t have high capacities. So in demanding applications, such as for phone batteries, they tend not to be used. I just chose the following two links out of a “random” search on Li chemistry battery cycle lifespan:
Proper Care Extends Li-Ion Battery Life | Power Electronics
Also, https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
The second link just above may be a site that is just aggregating info gleaned elsewhere. I notice that the first few figures that they offer in their web page text generate <404> Page Not Found errors but the web page seems to have a good rundown on factors affecting rechargeable Li battery lifespan.
In my initial spiel, I left out use and storage at elevated temperature as a major liability of rechargeable Li-ion batteries. Because of that, I’ve set 85 deg F as the upper limit of temperature at which I will wear my rechargeable HA’s for any extended period of time. If I get into the mode of getting new HA’s at Costco every three years, I’ll stop worrying about high temperature exposure and just let Costco refurbish my HA’s within the 3 year warranty period if I wear them outside while working in the yard at 107 deg F in Texas summer.
Is there a way to charge these batteries to keep as spares, and how long will they hold their charge without active use for emergencies?
The obvious thing is you can swap them with the main batteries to charge them up, then put back the main batteries when done.
No idea on how long they can hold their charge. But the thing about Lithium-ion batteries is that if you keep them fully charged at 100% for a long time without using them, it’ll be detrimental to battery shelf life. They’re happiest being at 50% state of charge for long term storage. Otherwise they’ll go bad prematurely if kept at full charge or kept nearly discharged all the times.
So keeping spare lithium-ion batteries is a bad idea.
One thing you can do is keep swapping them in and out -> alternate them. Meaning after the first set is fully charged, swap them and use the second set on day 2. Then the morning of day 3, swap again and use the first set on day 3. Then 2nd set on day 4, first set again on day 5, and so on. It’s still not ideal because your spare set will still sit around a whole day at 100% every other day. Again, not an ideal situation.
Pretty soon you’ll get tired of the hassle when you find out that most of the times, a set will last you through a whole day anyway. And even if they don’t, doing an short interim charge for 15-30 minutes to top it off by 12-25% in the middle of the day some time when you can is still less of a hassle than having to swap batteries n and out of the hearing aids every day. The battery door is not designed to be popped out and in easily and very frequently in the first place.
Wow, @Volusiano! I’m surprised by this post, as well as by @jim_lewis’, as well!
How can charging regimens this meticulous and intricate as the ones you gentlemen suggest be practical? I know we retired folks are supposed to have time on our hands, but - really - who wants to invest this much to eke out an extra few months from consumable parts whose service life is predictably finite?
Besides, as the industry rides the rechargeable battery curve up, I look forward to a battery change in 3 years or so, because the cells will probably be much better than the current ones (cost isn’t an issue - compare Li-ion replacement to 3 years of disposable batteries).
Speaking of engineering - I’ve always marvelled at how many open/close cycles the disposable battery doors can withstand before they pack it in. Rechargeables have different doors that are clearly engineered to meet different criteria than doors for disposables, and the ability to withstand thousands of open/close cycles is evidently not among them, given that to open the rechargeable door requires a special tool.
Personally, I’d have liked to have been given the choice of rechargeable versus disposable, but maybe the new Polaris chipset needs more current than the disposable battery can supply reliably?
Given the fact, however, that my Oticon More3s actually accomplish the goal of helping me hear better, to the point of being able to function fairly normally (versus my Unitron North Moxi Fit 800s that didn’t), I’m willing to transition to the rechargeable form constraint and wait for battery technology to catch up with the amazing Polaris chipset.
Nothing lasts forever (including me) and I’m certainly not going to be using a significant proportion of my waning years refigerating hearing devices and changing out batteries that were not designed to be thusly handled.
But that is just my personal opinion .
YMMV
Practical is in the eye of the beholder. It pertains to human health too. Some people find it practical to exercise on a regular basis. Others don’t. To me the takeaway is that I can likely prolong battery life if in general I don’t fully charge or discharge. I aim for roughly a 40-80% range, but I’m not strict about it.
Apples and oranges, methinks. But your regimen and attitude towards it seems reasonable. The other measures suggested don’t seem that way - to me.
As I said, YMMV.
I know - you’re already pegged to devote most of your time to your cats and lovely dog. Not a minute to spare for anything else! 
I used to spend about an hour a day in various aspects of taking care of a beloved old cat that was very enfeebled and needed a lot of help (plus about $1,000/yr taking care of the animal). Now that the cat is no more, my expanded personal time budget allows me to spend about 5 minutes a day doing what I described about only partially charging when I snack (like I go to the refrigerator to get a snack - 95% of the time I am doing something else - same as if I were brewing a cup of tea - might take 5 minutes to brew but I don’t do anything but start and stop the brewing - so the amount of time involved here is being greatly exaggerated by Mr. SpudGunner). And I don’t do the refrigeration bit with HA’s - only with watch and phone that are both moisture-resistant and have much higher heat capacities and hysteresis in cooling and heating.
But when I pay about $1500 this fall for an iPhone 13 Pro Max (or whatever it’ll be called) with 1 Tb storage, I want it to last 5 to 6 years. My brother-in-law had an expensive out-of-warranty iPhone that he took to an Apple Store to get the battery replaced for $80. They told him no-can-do, the battery pull tab was broken (he thinks the Apple Store broke it in trying to replace the battery), and they told him that his only option was to buy a new iPhone(!). He bought a $30 do-it-yourself kit, risked trashing the phone, and managed to replace the battery after several hours work (but he’s unsure how water-resistant it is now). My less than a few minutes a day hopefully will prolong the life of my future iPhone, avoid having to pay $1500 every 2 to 3 years to get a replacement, hopefully, and avoid screw ups like my brother-in-law experienced by trying my luck with an Apple Store battery replacement. (I’m trusting my brother-in-law straightforwardly related his Apple Store experience). And I can spend the extra $1500 to $3000 on something else (like an Nvidia RTX 3090 GPU with 24 Gb VRAM to support the double image in a VR headset at ~4K resolution).
BTW, for folks who are big on “just trash it and get something new,” I recommend watching David Attenborough’s “A Life on Our Planet.” You can stream it on Netflix. He created it as a life testament to his feelings about the future of the planet after a lifetime exploring the disappearing wild. He has some pretty sobering statistics. Something like 60% of all birds on earth are now industrially raised chickens. Don’t know how solid or accurate his figure is that 95% of the animal biomass on the planet is now humans or animals being raised to support humans and wild animals are just 5% of the biomass. He predicts we’re going to be able to celebrate being part and creators of a 6th great mass extinction event on earth if we keep on our present course. He’s pretty sharp for a 93-year-old geezer.
Attenborough’s bio: David Attenborough - Wikipedia
In 1936, Attenborough and his brother Richard attended a lecture by Grey Owl (Archibald Belaney) at De Montfort Hall, Leicester, and were influenced by his advocacy of conservation. According to Richard, David was “bowled over by the man’s determination to save the beaver, by his profound knowledge of the flora and fauna of the Canadian wilderness and by his warnings of ecological disaster should the delicate balance between them be destroyed. The idea that mankind was endangering nature by recklessly despoiling and plundering its riches was unheard of at the time, but it is one that has remained part of Dave’s own credo to this day.”
… WOW! it’s too hot for me in this kitchen! They’re just material things with finite (engineered so …) lifespans that we can do only so much to prolong.
Anyway, to each, their own. I have cats to look after!
I doubt anybody on here besides us cares, but some links you might find interesting. Regarding percent birds being chickens: How many birds are chickens? - Full Fact
My take: As stated, not accurate, but if altered to biomass and including domestic fowl, pretty ballpark. Wild animals: Tricky depending on definitions (if fish are included really throws things off) https://www.pnas.org/content/115/25/6506
Undoubtedly humans have had a profound impact on the planet.
Your regimen seems like a fun game for you. Would question net overall benefit of refrigerating batteries (energy use in opening doors), but it makes sense that it could prolong battery life. My game is trying to see how low we can keep household electrical consumption. We average about 120KWH a month most of the time, with up to 200 KWH for August and September while others in our area are often using over 1000 KWH during those months. Cheers.
Sort of defeats the purpose of rechargeables. Makes more sense to me to use them as intended and replace if/when needed.
With the swapping plan you are buying two sets of batteries whether you need them or not.
The 'range anxiety’s most people are concerned about does not really seem to be an issue with those who are actually using rechargeables, myself included.
Jim
@SpudGunner It’s NOT practical!!! If you read between the lines, I was trying to show @gkumar how much of a bad idea it is to try to keep a set of spare batteries for the rechargeables. That is why I went on and on about having to do this, then that, then keep in mind about this, then about that! It sure riled you up just reading that process, didn’t it? 
In the end, like I’ve always advocated before, the best way to solve the issue of battery anxiety, if it’s even a real issue to you in the first place, is to top it off mid-day or when you get home from work, whenever you have 15-30 minute down time, to get an extra 12-25% in to make it last until you go to sleep.
You probably don’t know the history, but this is not the first time @gkumar asked about using a set of spare batteries to ease battery anxiety, and I’ve answered this question for him in another post before along the same line as I did here. So I guess I tried to go overboard here just to emphasize again that it’s not a practical idea in the first place.
@zuikoholic Exactly! I DON’T advocate the swapping plan. I made it sound as cumbersome as possible in my post just to show my point that keeping an extra spare set of rechargeable batteries just to ease a little bit of battery anxiety (that’s most likely unfounded) would create even more anxiety in other ways than being worth it.