Weird coin battery behaviour

[Wowbagger]

The car is complaining that the key needs a new battery. It takes a CR2025. I have a "new" (Kodak make) one just taken out of its cardboard/plastic wrapping (I actually have no idea how old it is).

I put it in the key and it doesn't work. Yet my thin gummy meter says it's boasting 3.25V.

The old battery (Panasonic) displays about 2.9V. It does work.

This implies a poor connection on the new battery, but I can's see how that can be. I've given it a Good Rub on coarse cloth.

Any ideas please, panel?

I have ordered some more which are due to arrive in a day or two.

[Wobbly John]

The new coin battery may have too high internal resistance meaning the voltage drops when current is drawn. Which is likely to be an age of its internal chemistry.

[Kim]

The new cell may be coated in bittrex to stop children eating it^[1].  This can make for a poor contact with some types of battery spring.


_{[1] Primary lithium cells have enough voltage to electrolyse salts to hydroxide, which will then eat through the tissues of the digestive tract.  Which is a form of Type 3 Fun that you don't get with ~1.5V cells.}

[Wowbagger]

I have just found a manufacturing date of 01/2018. I wouldn't have expected that to be a problem given that the car was registered in September 2019.

[hellymedic]

These things are also VERY temperature dependent.

David has had endless cold weather unreliability of a wireless bike computer, which he’s replaced with a wired Cat Eye Velo 7 this evening (CR 2032, like many of the gadgets we have).

Coin cell numbers refer to their dimensions. A 2032 is 20mm in diameter and 3.2mm thick.

Coin cells can be lethal to small children if swallowed, as they can cause electrolytic burns to the gullet.

They look benign but aren’t!

[Duckfoot1606]

Coin cell numbers refer to their dimensions. A 2032 is 20mm in diameter and 3.2mm thick.

Thanks, I just learned something 

[Feanor]

I had that recently with my car key.
It was complaining that the battery was low.

I replaced it with a 'new' one that was a few years old, and it still complained.

I just bought a new-new one and it worked.

[Mrs Pingu]

Same with the kitty doorbell, the ringer seems to be quite sensitive to batteries, even from the same pack.

[Polar Bear]

I have discovered through trial and error that our VW keyfob likes the blue Energizer coin cells.  Most others seem to cause the key fobs to glitch.

[Diver300]

The new coin battery may have too high internal resistance meaning the voltage drops when current is drawn. Which is likely to be an age of its internal chemistry.

This.

The internal resistance of many cells goes up as they age or are used up.

[hellymedic]

David first replaced the battery on his computer transmitter with one of my ‘stock’ batteries but then bought a new one from a shop.
Still had issues in cold weather.

[Wowbagger]

I found, when I used a Cateye computer, that Panasonic batteries were the most reliable.

[rr]

I had this this weekend, our Skoda showed a key battery low warning, so I purchased 2 Duracell 3020 batteries from Mr Sainsbury's (after googling the size, as the handbook omits this piece of useful information).
Got home and fitted a replacement, didn't work, took it back out and removed the bitex sticker and put it back, then worked, mini takes it out for the evening. Next morning it didn't work again.
I took out the battery, my multimeter and my 4.7kΩ shunt, just under 3V, try the other one in the pack, 3.2. so 50% failure rate in Duracell batteries with a production date of January this year.
I think the shunt thing I learnt from Kim on here, but it really helps to identify batteries on their way out.

[barakta]

A friend is having similar issues with hearing aid batteries (the brown 312 size) bought online from Duracell a 50% failure rate either out of the box or very soon after. He's most pissed off and is going to try another brand, but liked Duracell cos they had big tabs which were easier to get on/off (he has huge hands and 312s are TINY).

I had thought possibly "fakes" but I am beginning to wonder if modern electronics are SO marginal that it's legit batteries but the margin is so fine, half the legit batteries don't work.

[Polar Bear]

I wasn't expecting coin cells to deteriorated with age but clearly they do.

Am I understanding from this that keeping cells for "when they are needed" is not necessarily a good thing and that a wipe over with rubbing alcohol perhaps to remove any applied substances before use would be a good thing?

I think that I'd prefer a good old fashioned key now for reduced faffage.

[tom_e]

A friend is having similar issues with hearing aid batteries (the brown 312 size) bought online from Duracell a 50% failure rate either out of the box or very soon after. He's most pissed off and is going to try another brand, but liked Duracell cos they had big tabs which were easier to get on/off (he has huge hands and 312s are TINY).

I had thought possibly "fakes" but I am beginning to wonder if modern electronics are SO marginal that it's legit batteries but the margin is so fine, half the legit batteries don't work.

Modern electronics shouldn't be particularly marginal with the batteries they're designed for.

But recent Duracell batteries with bitrex coating ARE a problem.  Well intentioned for sure, but prone to intermittent contact difficulties depending on the battery holder.  They're clearly designed to help with a dangerous problem, and I'd like to applaud that.  But they're not suitable for use as batteries.

[Kim]

I wasn't expecting coin cells to deteriorated with age but clearly they do.

All batteries self-discharge, but half the point in using lithium primary cells for applications where the current draw is zero most of the time^[1] is that it's extremely low.  They should have a shelf-life of years, and a decade seems reasonable.

On a related note, I saw someone outside yesterday acting suspiciously, who I eventually realised was playing try-to-unlock-the-car-with-the-one-physical-door-lock, presumably due to either a non-functional key remote or bat car flattery.  He was looking things up on his phone, and prised some sort of cover off the door handle to reveal the keyhole of a lock that didn't appear to work.  After a while, he gave up and wandered off in the direction of the shops.  The car has gone now, so presumably it got resolved one way or another.


_{[1] Presumably modern car keys that are detected by proximity wake up at intervals to do some sort of beacon signal, and therefor eat batteries a lot faster...}

[Kim]

But recent Duracell batteries with bitrex coating ARE a problem.  Well intentioned for sure, but prone to intermittent contact difficulties depending on the battery holder.  They're clearly designed to help with a dangerous problem, and I'd like to applaud that.  But they're not suitable for use as batteries.

I'm inclined to think that this is mainly down to over-use of coin cells.  Lithium coin cells aren't a new thing, but for decades they were only found in specialised applications like cameras, calculators, watches and car keys, where replacing the battery was a special occasion (quite possible that you'd employ someone with precision tools to do it for you).

These days, since electronics has become so low power, they've become ubiquitous as a means of powering all sorts of small gadgets, including things like bike lights and children's toys where they're a shocking waste of lithium^[1], so there's a much higher risk of them lying around where children can swallow them.


_{[1] Worth noting that there's an order of magnitude more lithium in a primary lithium cell than in a lithium-ion rechargeable.}

[Wowbagger]

My Panasonic batteries arrived today. I've put a new battery in the car key and it works ... so far.

[Diver300]

_{[1] Presumably modern car keys that are detected by proximity wake up at intervals to do some sort of beacon signal, and therefor eat batteries a lot faster...}

The wake-up device on some modern car keys is passive. 3 coils at right angels in the key are energised by a low frequency magnetic field generated by the car, much like the way that a credit card is energised by a card reader. In the car key, it only needs enough energy to be detected by a circuit that takes no current or nearly no current until triggered.

Once triggered, the higher power stuff starts to work.

[hellymedic]

Video demonstrating coin cell damage to sliced bacon… (experimental oesophagus surrogate)
https://www.youtube.com/watch?v=YXGYGG8D82s

[JonBuoy]

This is only vaguely related but...

My Salter electronic kitchen scales started displaying the low battery symbol some time ago but seemed to be functioning OK until earlier this week when the display still sprung into life but they wouldn't 'zero' themselves.  I popped a replacement 9v PP3 battery in and all was well.

I have no idea how long the previous battery was in there but it had a best before date of March 2022 and was down to 6.7V.  I was surprised/impressed that the scales were still fairly happy at that level.

[hellymedic]

I have an ancient Boots kitchen scale (I think I bought it in 1993) which runs on a PP3 battery. (It’s a real battery, rather than a cell, if you’re a pedant!).

I can’t recall if I’ve changed the battery since 2000.

Scale worked fine last time I used it!

[Kim]

AFAIK the Maglite with Woolworths C-cells with an expiry date before EldestCub was born still works...

[Wowbagger]

I bought Jan a Pulsar digital watch when our younger son was born, so that she could time his breast feeding accurately. She still wears that watch, and has changed its battery twice - once when he was 15, and the second time when he was 30. He will be 40 in September.

I should add that he has since been weaned.