Hearing aid batteries

[Jurek]

Mum gets through a fair amount of these.
They're tiny ones which chuck out ~1.5v and are supposed to be replaced on a weekly basis.
I've just put the Fluke across the 'dead' ones I have here before I collect  enough of them to warrant a trip to Curry's PCW re-cycling bin.
Most of them are showing >1.3v
At what point (on the scale of volts) should I consider them as legitimate re-cycling fodder?

[Jaded]

Do the hearing aids make a beepy noise thing when the power goes too low? I've not checked the voltage of the dead ones though. Will go find my multimeter.

[Jaded]

Well, (a) data sheet says they are 1.4v and the dead ones are 1.1v
I cannot test a new one because they are ZincAir and peeling the tab off activates them, and then they have a limited life. Apparently.

[hbunnet]

I get 10 days out of my size 13s. The aids switch off with a bleeping noise when finished.

I haven't checked the residual voltage, they are Zince/Air technology.

[Jurek]

No. Conversely, they make a beep when she activates them and they're working correctly.

[Jurek]

They're Duracells - but I've not looked to see which chems generate the voles.

[Diver300]

The fraction of nominal voltage where a disposable cell will be considered dead is anybody's guess.

Some appliances are much better than others at using batteries down to the point where all the chemicals are used up.

With some battery chemistries the open-circuit voltage, as measured with a voltmeter, gives a good indication of amount of discharge, with others voltage stays much the same and the internal resistance goes up as the battery discharges.

Some appliances take spikes of current, so are more sensitive to the internal resistance of cells than others.

It's easy to forget how much effort goes into putting a half-way accurate range on the dashboard of an EV.

[Kim]

Zinc-air cells have an awesome energy density (better than lithium-ion), on account of the oxygen being effectively 'free'.  They're also cheap, and don't contain exciting chemicals.  But they self-discharge at a very high rate, and a typical hearing aid battery will be dead within a couple of weeks even if you don't draw current from it, hence the stickers.

What counts as dead will depend on the hearing aid, both in terms of how much current it will draw, and what the lowest voltage it will operate at.  I'd have thought most modern aids would produce annoying beeps as a low-battery never-quite-enough-warning, before conking out.  Older analogue aids would just sound progressively worse as the voltage drops.  It's entirely possible that the user's deafness precludes noticing any of these effects, hence instructions to change them preemptively.

[Jurek]

Zinc-air cells have an awesome energy density (better than lithium-ion), on account of the oxygen being effectively 'free'.  They're also cheap, and don't contain exciting chemicals.  But they self-discharge at a very high rate, and a typical hearing aid battery will be dead within a couple of weeks even if you don't draw current from it, hence the stickers.

What counts as dead will depend on the hearing aid, both in terms of how much current it will draw, and what the lowest voltage it will operate at.  I'd have thought most modern aids would produce annoying beeps as a low-battery never-quite-enough-warning, before conking out.  Older analogue aids would just sound progressively worse as the voltage drops.  It's entirely possible that the user's deafness precludes noticing any of these effects, hence instructions to change them preemptively.

That's very useful.
Thanks mate.

[barakta]

My bone anchored hearing aids still need 44 size (675 cell) batteries. Mostly the purview of Cochlea Implants and things wot need to drive a beefy transducer.

The current version gives me all of about 20s warning that it is unhappy with the flatness of the battery... Not helpful. Also sounds like shit for the last day or so, but it also sounds like shit for other reasons (I need to go back for a reprogramme).

I keep a handful of 13 and 312 size batteries in my main coat pocket on the grounds that friends often ask me for batteries and having spares in either size is handy. My mum uses 13s and a deaf mate used 312s.

[Diver300]

Also on disposable batteries, unless having them go flat at certain times would be especially inconvenient, nothing will be damaged by running them until they stop working. The advice to change after a certain time is partly avoiding situations where changing batteries would be a problem.

[Kim]

Also on disposable batteries, unless having them go flat at certain times would be especially inconvenient, nothing will be damaged by running them until they stop working. The advice to change after a certain time is partly avoiding situations where changing batteries would be a problem.

The drive for smaller more invisible hearing aids is a compounding factor here too, given that the typical user is likely to have vision and manual dexterity impairments.  It's much easier to do the fiddly task on your bedside table with the lamp and the magnetic pokey-thing and your reading glasses to hand, than in a bus queueueueue or whatever.

Ob-rant: Opening the battery compartment in lieu of an off switch.  Whoever came up with that is in dire need of reëducation.  Bonus points for battery compartments like those on barakta's current aids that require teeth tactics to open, because I thought we were supposed to be trying to avoid people eating the batteries.

[Jaded]

^ Ah - so that is why they won't replace free of charge ones with teeth marks...

[barakta]

My last bone anchored hearing aids had open battery compartment for OFF but this only required a small amount of opening.

This current (and the previous model of this brand) requires the compartment to be ALL THE WAY OPEN to the battery falling out point to turn the fucking thing off (or it squeals which I can't hear, cos it's not in my head). I constantly lose the battery trying to get hearing aid back in and on in the morning and sometimes lose the battery while trying to put the hearing aid on my bedside shelf.

A friend who uses standard hearing aids of this brand (Oticon btw) leaves his in mute overnight cos he can't dexterity the battery falling out crap. Sadly my battery life is short enough without adding overnight mutes to the equation.

I will make the Oticon engineers suffer if I ever meet them. STUPID and thoughtless design.

[Jurek]

So I ordered a load of batteries from Bezos.
I gave him additional bunce to deliver them to me by Friday - which he failed to do .
I went to see Mum today, and the issue has become irrelevant as she cannot find her hearing aids.
Hasn't a clue as to where they might be. 
It's going to be spendy to put that right.