battery use by dates

Hello,

I bought a few strips of LR44 button cells because I noticed a lot of the children's toys seem to use them now. Today I found a strip that I had lost, only it says use by January 2015. I will wait for something to go flat and try them to see if they still work. Do you think they will?

Why do batteries have a use by date? Not just these LR44 ones but any type. Do they self discharge? Is it that even sitting in the pack, their chemicals are reacting and eventually the reaction completes, making the battery flat?

Thanks, Stephen.

Reply to
Stephen
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The button cells in the car key fobs failed a good while ago. Being a sensible person I bought two new ones from Maplin for round about 7 quid. No cheap shit for me! They only lasted about 12 months. So I shoved in a couple of Pound Shop batteries which I'd had for ages. You get a card full of different ones for a quid.

18 months later they are still working fine.
Reply to
Mr Pounder Esquire

Probably unless you have contaminated them with sweat across the poles.

They tend to leak after a while as the stored chemical energy does gradually get used up by internal self discharge - although it is very slow in primary cells compared to early NiMH and Lead acid cells.

You will lose some battery life due to ageing but unless they are obviously leaking then you can still use them.

Reply to
Martin Brown

IME in 10 years time the majority will still be usable

NT

Reply to
tabbypurr

I have a similar experience. Bought a card of 50 batteries of assorted sizes many years ago for £1.90. Still working my way through them. Whether they still have the life in them that they did when first purchased, I've no idea, but at just under 4p each, who cares? They work well enough!

Reply to
Chris Hogg

The battery chemistry uses the chemical reactions to generate the supply of electrons (and holes!) in order to generate and sustain an electromotive force (voltage) whilst supplying current to an electrical load.

A perfect "battery" (or, strictly speaking, a cell) is one whereby the consumption of the chemical energy is entirely dependant on the drawing of current from its terminals. Unfortunately, the perfect cell does not exist so all suffer from a process referred to as "self discharge", in essence, unwanted side reactions between the constituent chemicals responsible for generating the supply of electrons (and holes).

The only cell that comes closest to being 'perfect' in the sense of eliminating self discharge when in storage is the zinc/air cell but only whilst its vent holes remain sealed with the protective sealing tape that keeps the oxidising effect of air from gaining access to the zinc 'fuel' within.

Once the protective tape is removed, just prior to being installed into whatever electrical device they are powering (classic use being hearing aids), they have a fairly high self discharge rate (months as opposed to years of shelf life with other primary cell chemistries). Normally, this isn't an issue in most applications where the use of such cells is mandated.

Next in line for extremely long shelf life are the lithium primary cells commonly seen in button and coin cell form. These have a shelf life of 10 years when stored at 20 deg C meaning they will only lose 10% of their initial energy in that time. If you are happy to base shelf life on a 20% loss, you will get a 20 year shelf life rating.

The ten year shelf life is the industry standard used by the lithium battery manufacturers to set their BB date but it's useful to keep in mind that those packs of lithium coin cells in pound shops showing the BB date as next (or even last) month are still a bargain worth purchasing since they ought to still have 90% or more of their designed capacity and won't be losing another 10% of that until you've left them stored for yet another decade.

The alkaline cell type comes next in terms of shelf life which istr is something like 5 or 6 years. Without checking, the percentage loss figure may be a larger value than the 10% quoted for Lithium cells, possibly 20 to 33%. The ordinary carbon zinc cells otoh, almost certainly will be based on a much larger capacity drop maybe anywhere from 20% to 50% and on a much shorter time scale, 1 to 3 years? You'll be able to get more accurate figures from wikipedia (or, indeed, the battery manufacturers' own data sheets) if you want more specific information than the general information I've just offered here.

Reply to
Johnny B Good

I tested a batch of unsealed alkaline cells 8 years past their BB date, and 75% of them were full or almost so. About 25% were of little use. IOW you can greatly exceed the BB dates in practice.

But not too far. My BB 1940 batteries are indeed dead.

NT

Reply to
tabbypurr

Yup. I have doubts about Maplin. I tried to do the right thing!

Reply to
Mr Pounder Esquire

Their 12 for a quid AA 1.5v batteries are utter rubbish. Not that I've ever bought them of course :-(

Reply to
Mr Pounder Esquire

Basically yes, but it depends very much on the type of battery it is. I also have reason to suspect the electrolyte attacks the seals eventually causing leakage even if the battery has never been used. Brian

Reply to
Brian Gaff

Reply to
Brian Gaff

In all manufacturing and then retail it helps if possible to mark items with a production date or code so as to allow for rotation of stock; everything from tins of beans to watches and aero engines

As others have said different battery types and makes deteriorate at different rates if at all. But nevertheless most customers won't know this, without consulting data sheets etc. and so can be spooked into binning quite useable items. So that the production date which is already of benefit to manufacturers and retailers can be transformed into a marketing tool/gimmick in many cases by being converted into a use by date.

michael adams

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Reply to
michael adams

Reply to
Mr Pounder Esquire

What do you mean by unsealed?

Reply to
pamela
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Forgotten where your delete key is?

Reply to
Huge

There used to be a series of very rugged NiFe cells that use the same chemistry as alkaline cells, but were also rechargeable.

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Reply to
Fredxxx

Good batteries. there's also a lithium iron or something..A123?

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Reply to
The Natural Philosopher

Tabbypurr was talking about primary cell but that one is a secondary cell. I'm afraid I can't see how it explains what an unsealed alkaline battery is.

Reply to
pamela

Presumably poorly made alkalines would not last as long.

I guess a bargain basement Chinese alkaline batteries with low grade chemicals and poor maufacturing tolerances wouldn't be certain of lasting those 5 or 6 years you mentioned.

Reply to
pamela

Try this:

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Andrew

Reply to
Andrew Mawson

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