Recharging strategy

Hearing Aids
#43

This site provides more information than you ever wanted to know about batteries.

tl;dr: “Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life.”

Deeper discharges put more stress on a lithium battery. You want less discharge per charge cycle than less, you want you charge more often rather than less. Waiting two days is unnecessary counterproductive.

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#44

@wilfried

Yes, thanks for posting. That was one of the sites I looked at to let me know that daily charging was just fine,
maybe even preferable.

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#45

On the Ford EV forum the is an engineer at SWRI who tests batteries for a living. The advice he offers from his extensive testing experience agrees with what I’ve read. I’ve also read peer-reviewed scientific papers that say the same. You’ve never mentioned the expansion and contraction of a cell lattice as the battery is charged and discharged and that’s a factor in lifespan and related to depth of discharge.

Sorry for the length of the following but note there are references to published papers.

Copilot:
Yes, chemical reactions in lithium-ion batteries can vary significantly at different states of charge (SoC) A. At very high and low SoCs, certain reactions can occur that are less likely at around 50% SoC B. For example:

  • High SoC (near full charge): At high states of charge, lithium plating can occur, where lithium metal deposits on the anode, potentially leading to safety risks and reduced battery life B.
  • Low SoC (near full discharge): At low states of charge, the anode material (often graphite) can become fully lithiated, leading to structural changes and potential degradation B.

These reactions are influenced by factors like temperature, current, and voltage B. Maintaining a moderate SoC (around 20-80%) is generally recommended to optimize battery life and performance.

Let’s just agree to disagree and leave it at that.

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#46

This may well be why my Cochlear Kanso 2 processors have lasted almost 5 years without battery life lost.

Makes sense.

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#47

I have been wearing aids for 20 years and rechargeable aids for over 5 years. I charge my aids nightly. My devices like tablets, and phone i charge as needed.

#48

I’m not sure if this thread is intended to be for phonak only, but I have oticon moores, and my audi can replace the batteries in her office in 10 min. She told me that if the battery starts not lasting as long as it did she has the authority to change them under warranty. Once the warranty is up she will do it for a fee (I think she said something like ~$60 CAD per aid? but I might be wrong.) I don’t have any specific statement to this effect, only her word. But unfortunately the latest Oticons - the Intent have gone back to a battery that can not be replaced in the audis office. However I am told that it is still covered by warranty - although it has to be sent back.

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#49

the only problem with blanket statements, is they dont cover the myriad of variances involved. Charge rate, discharge rates just for starters, BMS specs, number of cells, matching of cells, etc

Much of what you folks quote is based upon hiC discharge and charge rates

I’ll leave it at that

#50

I do stand corrected, I meant to say the charger. I’ll edit my comment.
Thx

#51

(post deleted by author)

#52

From a CT Scan, it indicates a BMS (Battery Management System) in the hearing Aid.

I’d expected given the form factor, it would have been cheaper to put the intelligence into the charger, but its in the HA

#53

Yes, I saw that after I edited my comment.

image

#54

I’m not sure if all Li-ion batteries have the safety feature but more sophisticated ones have a chip and a monitoring system to tell when they’re completely drained and dangerously depleted. Then they use a small reserve of power to fry their charging circuit so they can’t be recharged because a dangerously depleted Li-ion battery is much more of a safety hazard if you try to recharge it.

My Sony camcorder batteries must have such circuits as they slowly deplete themselves whereas my Nikon DSLR batteries are much more stable to just sitting around.

I don’t know/remember all that much about batteries but it’s too bad one can’t have Li-ion batteries that you can just leave sitting and come back a year later and still find ~the same SOC. My rechargeable ReSound Quattros (my current backup HAs) and their charging case need to be charged up at least every few months to avoid having their batteries depleted. Kinda tedious…

#55

That’s a BMS I mentioned earlier.

Manages charge discharge and cell balance.

A good BMS will not drain a battery.

I’ve had lithiums I’ve stored fully charged and months later remained at full charge.

You shouldn’t do that, but a well designed system will not drain.

#56

So there is room for improvement in Phonak Roger microphones, because at least my Roger Select as well as Roger On V1 (non-IN model) can be partially discharged after a few weeks. Anyone have similar experiences?