Battery Shelf-life

All quality batteries I have seen these days have a "shelf life" date printed on them. Energizer, and Duracell come to mind. All batteries have a "self-discharge" rate, and all of them are going to have less capacity as time goes on. Quality batteries are going to have a slower self-discharge rate, as compared to cheap ones. Also, different battery chemistries have a different discharge rate, with Lithium batteries having one of the best shelf lives.

Back to your original question, if the batteries have no "manufactured" or "use by" date on them, you really have no way to know what you're getting. As you said, an unloaded voltage check is not going to tell you much, a loaded voltage test will not tell you how diminished the capacity is, but it might tell you if the battery is nearly dead .

Tom

are you talking about lead-acid batteries or the small alkaline? what type of batteries...

Lead-acid (the type you find in your car) have an average life of 5 years whether on a shelf or even if been on charge the whole time. The way to test the battery if you do not know its status, is called a load test. There are many load and simulated load testers on the market today, and depending on the amp-hour or cold cranking amp rating of the battery, the type of recommended load test varies. I personally like the Texas Instrument TIF tester, as a easy 12V tester for any lead acid battery (as long as it is a 12V battery. and no I don't work for TI. If you don't want to invest in a testing device, you can use a car inverter and plug in a load less than the amp-hour rating and put a volt meter across the battery and see how well it holds its charge. If you are not sure about this procedure do not do it, because you can blow up a battery if the load is too much.

Just the small non-alkaline battery, especially the size D,C, AA,AAA and the 9.0 Volts type. These are commonly used for flashlights, portable radios, TV remote,wall clocks, toys, etc. Some manufacturer do put the expiry date but many do not have.

You can get what are called "survival batteries," which are not active batteries until you grab them and give them a twist. This drives the active parts together and starts them off as batteries.

It depends on your luck because no manafacturer stamps nither date of manafacture nor use before date.They just stamp year and month of manafacture and really takes lot of effort to locate where it is stamped if at all its visible! It seems manafacturers are taking consumers for big ride.

crm

I wouldn't bother using anything lower quality than an alkaline.....

Not even a bovine?

"Battery Shelf-Life in my soup..."

- Shirley Temple while she was drunk and surly

Ya know, for some guy with a pacemaker in his chest, I could see this amount of concern. For some engineer that has a piece of equipment that he makes his living by, OK, add a couple of packs into your toolkit every now and then.

But for the rest of us, woof!!! Just do what humanity does, go to the store!!! Batteries have become so important I can't think of a single store (including my local liquor store) that doesn't carry batteries!!! Yell out your car window "Yow! Anybody got some spare batteries?!" I'm sure someone will hook you up in less than a minute!

Batteries are so abundant and easily available, that I for-see a time when they (instead of global warming) will be the single biggest pollution problem threatening the existence of man!!!

So... "It says 1.5 Volts, but I just know it's only 1.2 Volts! Oh, why did I buy these batteries on sale! I'm doomed!" I think you really need to be concerned with a whole different chemical process - they're called psychotropic drugs! There's a bunch of them out there that will help you calm down and put batteries back into perspective!

A car battery kept fully charged by a trickle charger can last 5 years. A fully discharged battery can be ruined by sulfation in 3-6 months. Sulfation reomes active chemicals from the battery via an irreversible side reaction on discharged batteries. The same reaction also proceeds on charged batteries, leading to their 5 year life. A dry charged battery can last 100 years or more. This is a battery make in the charged state, but with zero electrolyte. To use you add battery acid and drive away.

Some people sell chemicals to the unwise and unwary to reverse or prevent sulfation. All I can find are anecdotes. no hard proof of concep oher than self verifying web sites that sell these items,

Forget dry cells- buy NiMH cells- rechargeable up to 1000 times- they come these days in packs with a charger- dry cells, as with all cells/batteries, have a self discharge , unless the electrolyte is removed, as in vehicle (DRY CHARGED). As to renovation of cells/batteries, yes,it is possible- I know how to do it, & regularly do it- using home-made equipment.

you can renew some nicads, but sulfated lead acid batteries seem to be ruined and the sulfation mechanism is not reversible and in time lock up all the available chargeable species in insoluble crystals. Some web sites sell desulfator machines. Other websites say these are no good.

I have to at least partially disagree. I certainly agree on using rechargeable cells! But whether NiMH depends on frequency of use. For devices that are used on a daily or weekly basis, and therefore recharged frequently, NiMH is excellent. But the self-discharge rate of NiMH is terrible. The NiCd battery packs for my 5-or-so year old Makita drill were getting down in holding capacity, so I went to buy replacements. When I saw I could get a new drill with NiMH batteries for about the same price , I bought that instead. I commonly go a month or two without using the drill; now when I need the drill, the old one still has enough energy for a few holes, while the NiMH one is totally useless until after being charged. By that time I have the holes done with the old NiCd, or if both are dead, then with the old reliable twist-drill!

For nicad, try discharging the battery completely in the freezer. Then give em a charge. I have no documented evidence for this procedure, just seen it work.

I generally agree, although NiMH seem quite variable in self-discharge rate. Some seem to help up very well. All the rechargeables do poorly, in my view in things like smoke detectors, TV remote controls, etc, where the load is very low, and where an alkaline battery will last for a couple years, but a rechargeable lasts for weeks or a month. But wow, for cameras, NiMH can hardly be beat -- far more pics on one charge than a brand new Alkaline can provide in its entire (one day in a camera) life. $2.00 for 1000 charges vs $1.00 for one.

For the original poster, I can't think of a way to adequately judge a battery in a store, if it has no expiration date. I'd say vote with your pocket book, and buy only those brands that clearly display a date. If the batteries are at home, the no load voltage is a pretty good indication of condition -- that's what the simple battery testers (typically with green, yellow, and red sectors in the gauge) are measuring, and they are not too bad -- they are certainly good enough to allow you to sort through old batteries sitting around, to pick out the good ones. I always compare to a new one, but it seems to be that a good alkaline measures about 1.45 v, and a bad one measures about 1.35. (But don't take my word -- I'm into the years when you load up on Ginko Biloba, aspirin, vitamin E, etc. to retain any semblance o memory.)

I honestly don't know what the questioner is on about... all the batteries I see for sale are clearly marked with their sell by date...

I always check this date especially when buying the short shelf life zinc carbon batteries....

John.

Perhaps it is true in your country, they are marked with expiry date, but not so in our side of the globe. I just checked some recently and no dates are printed.

ya can visit the manufacture site and download they spec sheets on batteries, which is good info, have used this many times. Alot of dry cells, name brand or not are made by the same folks, so the cheaper ones and the high cost name brand can be one in the same. dry cells will last longer if stored in a cool place, like in the ice box, bottom shelve.

in the same context, how efficient are battery chargers for Ni-cd batteries? And what if the batteries remain idle for say six months, do we dispose of them?

Rechargeable cells are the wrong choice for a device that is to be left 6 months without use. See my post #13.

It seems that nobody here has understood what you want to ask us, we have been all ober the place and got nowhere.

All I can add is either you only by cheap unmarked cells or you need to move to a part of the globe where they are clearly marked with date & shelf life!!

In case this did not help you, please re-state your question fully.

the cheap cells from Asia have less than 2 years shelf life. Good Asian cells can have 5 years shelf life. Here in Canada the law says the shelf life at 20C must be marked. every 10C above that reduces the life by 50%. Warm asian climates may be why they do not print a shelf life on them. cheap asian cells often corrode through the zinc case and the highly corrosive fluid can easily ruin the device. Most cells in USA/Canada are armored or steelcased. I imagine some may be plastic cased.

As in life you get what you pay for.

Recently faked duracells were found on sale here in Toronto, looked good, worked bad. A customer complained and wrote to maker on package. Now the faked duracells are similar looking in copper top color.

The packaging and the humidity both play a role in shelf life for batteries......as well as the original quality as well.

As someone mentioned, never put cheap batteries in expensive equipment, they just leak and ruin everything....

My wife buys cheap batteries and then never checks - she has ruined a good camera and many remotes.....some of which I took apart and cleaned and managed to get working again!!

Yes, Thanks! good information. Perhaps our local battery manufacturers should be required to put the necessary dates on their product.The ordinary consumers have really no way of knowing if they are buying an old product which will last only for a very short period and could even cause damage to their gadgets.

The cleanliness and humidity in the plant, as well as the speed of manufacture have a significant part to play in the process, as well as the actual quality of the seal. The dies and tools in a rotory battery sealer are prone to wear and machine adjustment to make any actual rating worth the text stamping machine it is required for, in the first place. If there is contamination at a cheap processing plant, all bets are off right from the start.

The un-battery lives.

Realy you can't imagine how long it may be.

I purchased a surplus item of WWII from old-sellers in 1956. It contained Cabon-zinc cells & were quite OK & worked more than new cells available at that time in the market.

Now see the cell for CMOS-BIOS. It runs for the life of PC

"Now see the cell for CMOS-BIOS. It runs for the life of PC"

What cell is that?

That may be true, if you consider the life of a PC to be 3-5 years. I have even seen a few old B&W computers whose battery was still good after 10 years. Some laptops use supercapacitors, that should last the life of the computer, but that is not a battery. I have replaced literally hundreds of computer backup batteries, and have yet to hear of a computer battery expected to last as long as the computer. Just today I turned on two 20-year old computers: one worked just fine; the other didn't. Please tell us more about these cells that last the life of the computer!

the ones that last the life of the computer with daily use are those that use a micrtrickle charge on the battery to keep it alive. These are usually small dual button nicads. If left on the shelf they can fail due to self discharge. Sometimes they grow carbonate 'fur' due to leakage and ruin the board.

The ones with lithium buttons cannot be recharged and often go dead, due to low quality. A good lithium should last 10 years.

I suppose a good rechargeable at the low duty of a backup battery could last 10-20 years when more or less constantly trickle charged.

My experience is mostly with Macs, where only the laptops use rechargeables, and very few laptops are still in use after 10 years, so they don't make a good test. The vast majority of Mac desktops use the 3.6V 1/2AA Lithium. These used to last 10 years, but now one that makes it to 5 years is unusual. I have never actually measured the load current (I will do that, as I happen to have a 20-year-old Mac open right now!), but I have assumed that the shortened lifetime was due to increased demand. I believe the first ones did nothing but keep the clock running when the computer was off; now they store all kinds of settings as well. On the other hand, assuming is always dangerous - perhaps they just don't make 'em like they used to...

bought by the lowest quotation

Agreed. Quality (or better said, the lack of) was not requested!!!

All it needs to do is get by the end of the guarantee....

I think that you made two very valid points with your last sentence:-

On the other hand, assuming is always dangerous - perhaps they just don't make 'em like they used to...

Well put......!

The cells were Zinc-Carbon, Size "D" used in American Mine-dtector, one of the equipment supplied to UK in WWII.

My son sent an IBM [I think 286 or 386, I dont remeber] some 11 years back along-with then the latest newly introduced Compaq Pentium Presario [simple; no 1 or 2; system-inf read it as 586 ]

I dis-assembled the IBM & its Bios battery was OK.

I can give you the MB's ID if I could go home in near future.

Since I'm a Mac guy, the MB ID would do me no good, but I am curious what kind and size of battery it was...

Yesterday I measured the current on the battery of a roughly 20-year-old Mac SE/30: it was 4 µA. The next time I take apart a more recent unit, I'll measure its current to compare.

Dick

Regards.

How you measured the current?

Just by putting DVM in "DC-Current" pos @ 1 mA range or how ?

I will try to convey the type of battery when I get chance to.

Hello Haajee

Actually a DMM (Digital MultiMeter), DC current @ 400µA range, between one end of the battery and one end of the battery socket. This is a 3.6V 1/2AA size lithium battery, normally held in a battery holder/socket - the battery used in the vast majority of Mac computers from about '86 to current. I haven't yet gotten a chance to measure the current in a modern Mac - I'll try to do that tomorrow.

Dick

This method you are using will work for most small batteries, but gives them a tremendous jolt, so to say, as basically there is no resistance in the circuit except the battery itself. But provided the meter has at least a 10 amp range selected first, this should not be a great problem.

Make the measurement as quickly as possible as you are discharging the battery at the maximum speed possible, basically a short circuit!!

Never do this with with car batteries or other batteries where the maximum fault current might exceed the measuring devices capability!!

A better method is to use specific resistances for each battery type that will test the "muscles" of the battery and just measure the voltage across the resistance. This will tell you more and without discharging it anywhere near so quickly.

Those simple battery test meters that you can buy cheaply are in such cases of single cells, a much better bet!!! They will not discharge or damage the battery in any way.

Check the reading of the old battery against a fresh battery of the same type so that you can see any differences......note these for future reference for each cell type and size!!.

With batteries made up of more than one cell, a voltage reading done in this way if done accurately, will yield enough info, provided the battery type is known, to decide if the battery is still good or not, rather than a short circuit current reading....

Andy,

I think you misunderstood, Dick's method was to place the ammeter in series with the battery (the proper method), he was not placing the meter in parallel across the battery (a dead short, as you said).

Tom

In series with what?

He is measuring current, he did not mention any other components......

Please place a simple circuit diagram on this Blog on how he measures current without doing what I assumed.

I have no problem with being corrected if the correcting person is correct!!

Correct me please!

Dick was using the ammeter to measure the current draw of his apple computer, not the maximum current output of the battery (micro amps, rather than multiple amps).

But provided the meter has at least a 10 amp range selected first, this should not be a great problem.

It is reasonable to say, "Never place an ammeter directly across the terminals of any battery no matter how small." There is a significant likelihood of ammeter damage (or at least blowing the internal fuse), permanent battery damage, or battery explosion.

An AA rechargeable battery can easily "peg" a 10 amp ammeter. Internal resistance is typically .035 in a AA NiMH, so 1.2V/.035 = 34 Amps.

Being like you more than a little careful, I have to admit I have not dome this to a modern battery of any type. In my childhood, I once connected a large D size battery across a meter and it could not even achieve 2 amps.....

So personally, I cannot believe that a single modern cell could over do this by more than 17 x.....

Have you actually performed this test yourself?

If not, I will try with a 10 amp fuse and a full charged AA battery when I have recovered from the bout of bronchitis that I have at present.

But my bet is that the 10 amp fuse will NOT be blown!!!!

Anyone else could do the test now and let us know. If the 10 amp fuse does not blow, then a meter could be substituted....

NiCads are a little better at ultra high discharge, but I think even a NiMH AA will output more than 10 amps. Consider that these are over 2000 mAH now (some are 2500) so 10 amps is only four or five times the AH rate (C). 15 minute chargers charge at 4 C, so I'd expect 4C discharge to be fairly easy for a battery. In AGM lead acid, one can routinely charge and discharge at 6-10C (and actually they are pretty happy doing this, if the voltage is kept below 14.5 [typically, depending upon temperature] in a 12 volt battery). The 32 AH battery used in a Mazda Miata is rated for 475 cold cranking amps and will typically supply twice that if warm, and with a high enough load. Many batteries of about that size are rated for pulse currents of 2000 amps or so (about 60C).

I haven't put an ammeter directly across an AA cell, but I have managed to put my keys across one while it was in my pocket. The short could only have occurred for part of a second, I'd guess, given the unlikelihood of maintaining a connection from a small terminal on one end of the battery, through the keys and chain to the other end of the battery. The battery was painfully hot (the reason I realized what was happening) -- far hotter that 1.2 V x 10 A (12 watts) would suggest.

I don't have a fast blow 10 amp fuse around, but I'd expect that it would blow. I'd also expect that the Ni MH batteries would put 15 amps (7C or so) into a load for a minute or two without damage to the battery. (If it were not for Peukerts effects, which are not too strong in NiMH, you'd expect a 7C discharge to go on for about 8 minutes).

I am not in complete agreement with your comments above, theoretically correct yes, but on a practical side, I feel that the maximum currents will prove to be far less.

The overheating by accidentally shorting, is of course well known and documented, but as what actual currents flow in practise, not!! Or at least I should say, I have not found any such infos in a quick search.

Even discharging at the theoretical rate of the battery, would produce a lot of heat with nowhere to go I feel...which would be less current than a short would produce one would imagine, but there my theory and probably practise leave each other apart!

The Lead Acid battery (wet cell), being quite a different beast(s), cannot be compared with single (dry) cell batteries, though what you said for LA, seems to be true, but may confuse other readers without your basic knowledge, when mentioned together....it is for example unusual to see LA in anything other than 3 or 6 cell versions Generally peaking.

In my youth, the pre-war radios still around in the early 50s, used a single cell LA as supply for valve heater current if I remember correctly! and model aircraft flyers, used them for starting their glow plug engines......thats about it I feel.

Let us wait till I am fit and I will try with a 10 amp fuse as promised on a modern AA battery and see what REALLY happens.....

Here is an invention that claims to have improved battery shelf life. What do you think of this invention? Looks like sort of shorting the terminal with a high resistance load.

Title: Batteries with improved shelf life Document Type and Number: United States Patent 3930887 Link to this page: http://www.freepatentsonline.com/3930887.html Abstract: This invention relates to batteries with improved shelf life. When a relatively high resistance element is connected across the terminals of a battery, the resulting low current drain inhibits the self discharge of the battery and thus improves the shelf life. The resistance element can be built into the battery or mounted externally. The invention also relates to a battery-operated article, such as a flashlight, having a high resistance load built into the article to contact the terminals of the battery to provide a low current drain when the article is not being used.

There is a possibility that it could help.

May in the same direction that certain capacitors (mainly electrolytic), when not recharged / polarised at reasonable intervals by being used / powered on, tend to break down chemically.....

I can believe that the patent could have something. Good that you brought it to our attention, thanks.

Andy,

Is battery shelf-life really this interesting/important?! Why not just keep a few extra batteries around?

If the battery industry is as sleazy and dishonest as you all seem to think, why not make your fortune by creating the first "honest" battery company ever! You could be like Douglas Adams Beer. You could send employees to each distributer with DMMs to check the freshness of the batteries. If they don't meet your standards, you pull them from the shelf and they're replaced!

No more bitching!!!

labor cost would kill that approach. If you look at the duracell 'pro' line you will find that it is a premium group of cells that are used by police and medical systems. A 9v pro is about $5 here in toronto. You can get the chinese ones for $1. People fill their kids toys with these cheap batteries at xmas and the toys soon run out of juice. The common consumer thinks they are all the same.

At the root of it is a lack of an enforced consumer standard rating under which a battery can be sold and a body of inspectors who go around and pull things off shelves and fine retailers for deficient/unmarked products.

Would be want this on batteries? A huge beurocracy? We could make it an adjunct of the CSA/ULL/DIN organizations so they could hire a few thousand roving battery men/women. Most people know and avoid the chinese crap batteries, and many retailers like Walmart, Costco etc will not buy them as they fail their purchasing quality controls.

With a set of standards and enforcement batteries that were not marked or were wrongly marked could be stopped at the border and taken from shelves.

Next we can hire some grammar and typo police, I would soon be in trouble.....

Batteries are the easy things. There's a new thread on Winnie the Pooh lead contaminated PJs for babies!!! Guess where they came from?

If we're going to have a world market, it seems as though we're going to need some sort of control between the manufacturer and the consumer. Or do you want your children to be eating nerve gas tainted breakfast cereal, and inferior batteries in their toys!!!

On the other hand, give some poor schnook a 100 mile territory to police. It could be done in a week. If not, out source it to another country. they'll get it done!

Or do you want your children to be eating nerve gas tainted breakfast cereal, and inferior batteries in their toys!!!

When I had babies, I made sure that they only ate high-quality batteries!

Yeah!!! Now that's the stuff I live for! Good one, Mr. Fry!!!

As tdesmit correctly said, the meter is in series with the battery, holding the positive end of the battery touching the positive end of the battery holder/connector, and the ammeter between the negative end and the negative connector.

It may be that the µ(Greek letter mu for micro) does not show correctly on your computer, so µA may not have looked like microAmpere. The 4µA current was measured using a 4-digit BK Precision meter set to a scale that measures up to 400 µA, or 0.4mA, and was measured on a Macintosh SE/30 (about 20 years old) with a new battery but a dead logic board. The dead logic board may or may not be drawing normal current to its PRAM chip; I'll try another similar Mac SE that IS a functioning machine (I keep at least a couple on hand, in case the one which controls a robotic tissue culture applicator machine we made about 15 years ago should fail).

I just tested a more modern (about 6 yr old) iMac, and it draws between 112 and 114 µA, or 0.1 mA. I'll try several others today. All the desktop computers I have are old - mostly ones I'm repairing or salvaging. For my own use I only use laptops. I'll post the results after I measure several more machines.

Dick

I think you all need a piece of paper and a pencil, draw a battery, parallel to it draw a meter, connect it with wires as you yourself have just said.

The battery and meter, being the ONLY components are in series with each other and in parallel with each other!!!

The only real resistance (if any) is that from the battery, very low!!! The meter will probably be in the micro ohms range at a guess......

The only thing that saves the meter is that the battery has not got the "OOOMMMPPPHHH" to do much damage!!!!!!

You all should think through exactly what you are trying to do!!! I do not believe I have made any mistakes in what I said at all, but if you can show me with a correct diagram that I am totally off my rocker, please do! I am ALWAYS willing to learn!!

Please look at these two diagrams and let me know what the ELECTRICAL difference is please???

Thank you for your close attention!!!!

No differance except that convetion of battery is wrong:

(+) terminal should be longer & (-) shorter

Does that make any difference??? Can you see that on a battery.

As long as you understood it was a battery and that one end was positive in relation to the other, what more do you need?

Hairsplitter.

C'mon Andy - you're smarter than that! Once again Tom is correct!

Here is a photo of the procedure:

It's a bit difficult to do the measurement with one hand and take the photo with the other... If you look closely, you can see that I'm holding the negative(black) lead of the DMM on the negative side of the battery, with the positive end of the battery touching the positive end of the battery holder. The negative(red) lead of the DMM is stuck in the negative end of the battery holder.

And here is the circuit (equivalent to Tom's):

There is clearly other circuitry in parallel with the battery. When Power is connected to the computer, whether it is turned on or not, there is less than 2µA current from the battery. After the power cord and battery are both removed, and I connect only the battery through the DMM, the battery supplies about 3mA (3000µA). If the battery is already connected when I remove the power cord, the current starts around 12µA, then drops to around 4µA over a few seconds. Apparently when I measured over 100µA earlier, it was transitioning between different modes of operation... I think I have learned that it is best to have the power cord connected when I change batteries. I have known for years that under certain circumstances, a new battery would go bad in just a couple of days - I have never known what those circumstances were... Perhaps until now: I'm thinking that if the original battery was removed or totally dead, then putting a new one in without the power connected makes it go into that high-current mode. Can anyone confirm or deny?

Dick

Excellent diagram, I thank you most kindly for your trouble, it does clear up that point completely.

But what does this tell you about the state of the battery? All it says is that X milliamps (or microamps or whatever!) flows, it does not give a full picture of the state of the charge.

I thought we were trying to find out the state of the battery???? Have I missed some vital point?

For that you need to know the voltage across & the current through a known resistance.....this test may say that the battery can supply enough current today, but it gives no indication about the state of it tomorrow....

The title of this thread is "Battery Shelf-Life". Under the low current drain of this application, the useful life is (or should be) nearly as long as the shelf life. I'm trying to determine whether the shorter useful battery life I've seen recently, as compared to 10 or 15 years ago, is due to heavier load on the batteries, or to reduced battery quality.

I just opened up a still-functioning Mac SE, manufactured Feb 12, 1988, but I couldn't immediately measure the battery current, as it has a battery with leads soldered in place directly on the logic board, and I don't want to cut or unsolder a lead just yet. The 1/2AA lithium battery is dated 0288, which I believe means the 2nd week of 1988, so it is the original battery. It currently has a voltage of 3.1V, and the clock indicates 54 minutes ahead (not corrected for Daylight Saving Time, so really minus 6 minutes), and the date is correct. Mac clocks are nothing more than oscillator/counters, keeping track of the number of seconds elapsed since they were set; the computer calculates the date and time from that. The battery is a Varta brand, made in Germany. So here is a battery that has been running an oscillator and counter (and, I believe, nothing else) for very nearly 20 years.

I commonly replace between 50 and 100 such batteries a year, and on current computers, I'm surprised to find one more than 5 or 6 years old. From the few measurements I've done so far, it appears that the problem is mostly battery quality!

Dick

So here is a battery that has been running an oscillator and counter (and, I believe, nothing else) for very nearly 20 years.

WOW!

I'm with you, your last sentence was:-

"From the few measurements I've done so far, it appears that the problem is mostly battery quality!"

...and I bet that you have put your finger right on the problem.....

I like Varta, even today.....for any type of Battery that I need.

Do you use Varta as a replacement Battery supplier for your Macs?

No, I haven't seen Varta available. I'm currently using SAFT, made in France. These I've been getting from a friend who has an alarm business - by buying 25-50 at a time, I think my last batch cost about 3USD each. If you buy one at a local electronics store, they cost anywhere from 9-15USD. If you happen to know of a company that distributes Varta in the US, please let me know. I must confess that I haven't yet tried finding a source on the internet - I'll have to do that!

Dick

Dick,

MCM Electronics shows two versions of PC batteries by Varta, unfortunately, no stock right now, and no pictures. Dantona is the distributor for MCM, and they have many Varta batteries listed along with pictures. In order to get Dantona's "where to buy" list, you have to fill out a web form.

Tom

Thanks!

Unfortunately, for the 3.6V 1/AA cells, they list 11 companies, but not Varta.

I looked around a little, and found Varta 3.0V, but not 3.6V. I'll try again later...

Dick

I'm guessing, but I think that 3.0 volt must be a misprint....needs checking up on at least!!

I am sure they are not offering two old type dry cells (2 x 1.5 volts) rather than 3 x 1.2 volts.....

Perhaps it's one of those European things, but D, C, AA, and AAA batteries here are printed with 1.5 Volts on the side. You be the judge.

Which of course is really false......!

You may be right - I have wondered for years how they got a 3.0V lithium battery (I think I assumed it was a 2-cell with a different chemistry), but I never measured the voltage of any - till now.

For whatever it is worth, I had to take that Mac SE apart again and look: the almost-20-year-old Varta Battery is labeled 'Lithium 3V, ER 1/2 AA, Ord. No 6126'. It currently has a measured voltage of 3.115V.

I also opened up a second Mac SE, manufactured in early 1990. It has a socketed battery, Tadiran brand from Israel, labeled 3.6V and dated 02/90, which has 0.05V. Obviously the date was wrong on this one! I put in a new battery and set the date and time. As in the other one, the computer still works fine, including its 40MB hard drive and 800k floppy drive.

The cell voltage is just over 1.5 volts on lithium, so what you measured could be correct, so what this suggests to me is that different technology (battery wise) was used in the same Macs! I suspect that the 0.4 volt approximately difference dos not play any role in such cases......

Lithium had generally speaking a longer working life and/or shelf life....

Both batteries were lithium. The ones labeled 3.6V normally have 3.65-3.68V when new. I have assumed that this was 3-1.2V cells. For recycling reasons, Ive never taken one apart.

I've never measured the voltage of a new one marked 3.0V. Next time I get into Sacramento, I'll go to a battery store and see what I can find out.

Well thought out, I am interested in the results as I am sure a lot of CR4 members are too. Its an area we (or should I say I) seldom enter, we can all learn something here.

Hello Andy and all!

Well, I have just been educated a bit more... The guy I get my 3.6V 1/2AA lithium 'batteries' from told me that they are cells, not batteries, and he spoke with a tone that indicated he knew what he was talking about. He also indicated that the 3.0 V 1/2AA 'batteries' are a different chemistry.

I had always assumed that the 3.6V was from 3-1.2V cells in series. As I said once before in this thread, assuming is dangerous! Today I finished cutting one open (not a trivial task - the case is a fairly heavy deep-drawn steel can seam-welded to the top, with just a small hole for the Positive electrode to pass through). Still a strong sulfuric acid smell after having broken the seal about a week ago, left outside in partly rainy weather so water could react with the lithium... It IS indeed a single cell; one anode and one cathode! I had never heard of single cells providing that much voltage!

I have only the one 3.0V lithium cell ( the one that has been working for nearly 20 years), and I want to leave that one as is to see how much longer it keeps working.

If I come across another 3.0V unit, I'll cut it open to see what I can see.

I hope someone finds this as interesting as I do...

Dick

Oops! I just noticed that I said negative(red), when of course it should have been positive(red).

Andy, you left out one key element, the load. In this case, the load is the battery backed-up RAM in the computer. This type of RAM has very low current draw by design, so it can be kept up with a small battery, or in some cases, a capacitor.

Tom

Either the load should be at least for 10 mA. The Button batteries are tested just for a touch of test prods. Any how it does not discharge in 2/3 seconds @ 10 mA. However if you test it in-Cct of BIOS your BIOS settings will go to default.

Regards

It's not real clear in the photo (post 44), but these are not button batteries. The 1/2 AA battery is just under 15mm in diameter and just under 25mm long.

I'm using whatever is normally connected to the battery as its load, just inserting the current meter between one end of the battery and that end of its holder. In Macs, this battery is referred to as the PRAM (Parameter-RAM) battery; it runs the clock and stores settings in the absence of power. I assume this provides essentially the same function as the BIOS in PCs.

Dick

Regards

I really know a little of Mac, but it is assumed that "BIOS" function is also necessary, what-ever the name is.

At last I found that battery,

It is CR2032 by Sanyo.

I asked my son if he had replaced sometime before he sent the PC, but didn't remember.

It is still good though the motherBd was put in junk

OK, now how old was that motherboard?

By the way, the fellow I get my 3.6V 1/2AA batteries from insists they are single cells. I've never heard of a single cell with that high a voltage! Not wanting to pollute, I've never taken one of them apart, but I want to know, so this morning I started to break one open. In the process of course I broke the seal and shorted the contacts - I then noticed a rather strong odor, possibly sulfuric acid, so for the moment at least, I stopped and took it outside. I'll try to see if I can find something authoritative on the internet...

Dick

As I remember my son sent it in 1996/7, but it was long used.

Regards

The MB is not Mac but IBM ??? No Marking on it.

It was sent by my son some times in 1994/5 & was used.

Early Pentium's time when it was called 586.

I assumed it was one of the IBM type. Apple never used button type batteries except on laptops.

My condolences to the victims of the bombings in Pakistan - I trust you were not affected directly! I certainly don't know what can be done about these extremists!

See also my next post for Andy.

Dick

Lithium is the highest on the electromotive scale.

Look here.

http://www.britannica.com/eb/art-61158

often you can make cells between these pairs, but not awlays

Thanks - its been too long since my last chemistry class...

Now looking at that chart makes me wonder how they ever get the 1.2V from the Ni-Cd pair!

Dick

As a general note..

Even 'reputable' Alkalines can be extremely variable...and manufactures data on capacity is best desribed as vague!

One of products uses 4xD cells (reputable alkaline made up as a pack by a reputable company) Calculated life in use ~ 1.5 years, (confirmed empirically) we claim 1 year... most are fine but we get a steady trickly of early failures (9months) where 1 cell is dead whilst the other 3 are still up at about 1.3v. Of course the battery supplier/manufacturer are not interested... The early failure screws up our customer's planned replacement schedule, and of course he thinks it's our fault.

(And yes I've checked the units the failiures are installed in.... there is no correlation)

If you had lived in Germany, the Battery company would be liable as he has to give a 2 year guarantee here and one cell going down (1 bad 3 good) is a clear indication of a fault in that one cell.

It would be interesting to replace that one cell and see how long the rest work for before they collapse.....just to see what COULD be the life expected when 50% or more have failed.....

By the way, it would appear to me a good reason to change your battery supplier, in tests published on the Internet, Energizer came though best in the smaller sizes. Check the link out at the bottom....but only Energizer D cells were tested I see in that size.....

I use Energizer because I always thought they were good, but probably not as good as Duracell, but Duracell are rarely obtainable anywhere as cheap as Energizer is.....so really I went for cheap but good, but as I mentioned earlier, often in tests better than Duracell....(but I did not know that then!)

May I draw your attention to the following website as somewhere to start your reading on this subject:-

http://www.zbattery.com/batteryinfo.html

I hope it helps you to keep your customers happy......even making your own sets up could well improve performance dramatically I feel!!! Maybe the spot welding (to make up the battery pack) is being done too often / inaccurately on some cells.....warming them up too much!

A high quality battery holder will not work for you for example???

It would be interesting to replace that one cell and see how long the rest work for before they collapse.

Yup..done it...they were fine.

Energizer ..yup again. (we may switch to Duracell, 0nly a small price increase.)

I don't need extra reading...I appear to know more than the folks at Energiser will admit to..!

Cant remember the exact figures..but quiescent is abot 200uA 24/7 with 0.3A drawn for about 5 mins a day... (ish!)

Cheers for the input

Del

If you looked at the website i mentioned before, in terms of capacity with the smaller sizes at least, the Duracell is way down the list.....

Maybe I would have...if you linked your links !

Hightlight the word you wish to be the link.... click on the link symbol (world and chain thing) box appears... with the 'text' which links to the 'URL' type or paste your web addr into URL and then submit (Kris runs and 'advanced linking class' for a small fee ) They go blue when it works.

It is a great help for lazy gits like me...saves copying out the address (don't seem to be able to copy from posts too easilly..or maybe that's just me?)

...I knew Cats were basically lazy (we have two!!), but this is ridiculous!!!

No seriously, thanks for the tip, I will try it out right here for you!!! (I am always friendly to nice Pussies.....!)

Here it is again in Pussy Cat format! Miaow!!

http://www.zbattery.com/batteryinfo.html

Hey nice site ... cheers Andy, it does compare the 2 D cells I'm interested in and the Duracell does come out slightly higher avg Ah and avg W

D Energizer Industrial Alkaline 2 0.8 13.0576 13.6423 D Duracell Procell Alkaline 2 0.8 14.6918 15.2155

Greetings CR4 group!

Related to this topic, here is a good link that explains all about batteries!

http://www.buchmann.ca/article23-page1.asp

http://www.buchmann.ca/faq.asp

http://www.buchmann.ca/Article4-Page1.asp

Regards to all

My reply to:

Andy Germany #46

****************** Quote ******

Does that make any difference??? Can you see that on a battery.

As long as you understood it was a battery and that one end was positive in relation to the other, what more do you need?

****************** Quote Ends ******

Had you drawn 2 equal parallel lines & marked it as "battery' & given (+) & (-) signs, it was OK as far as understanding is concerned.

But your post # 20

<Please look at these two diagrams and let me know

what the ELECTRICAL difference is please??? [Fig: here]

Thank you for your close attention!!!! >

called my attention to piont-out the norms of Circuit diagrams' conventions.

It is pointless to attempt to define universal conventions.

A far better (and universally accepted practice) is to avoid using an "Convention" until the word has been spelled out completely and the associated "Convention" defined. For example, A capacitor [ --| |-- (C)] ..Thereafter [ --| |-- (C) ] can be used in the Circuit Digrams, articles, papers or posts without confusion.

How if I mark a cell's (+) end black & the other Red ?

Regards

#48 & #52

********************** Quote2 ***********

1.)

I'm with you, your last sentence was:-

...and I bet that you have put your finger right on the problem.....

&

2.)

"From the few measurements I've done so far, it appears that the problem is mostly battery quality!"

********************** Quote2 Ends ***********

Not only batteries but all the products have de-graded quality than those of 10/20 years back.

It was pionted out in an-other topic that the quality of Floppy Drives & Media has so much

de-graded that hardly any is read or reads. Some 15/20 yrs back used floppies from Microsoft

1.66 MB floppies were available 2 quite cheap cost & worked for years after.

Now get a caton of floppies, 2 out of 10 will not right away & the other lot will die within a month.

************** Quote3 *********

Del #54

As a general note..

Even 'reputable' Alkalines can be extremely variable...and manufactures data on capacity is best desribed as vague!

...

************** Quote3 Ends *********

And to: #56 Andy Germany

********* Quote4 ********

... and one cell going down (1 bad 3 good) is a clear

indication of a fault in that one cell.

********* Quote4 Ends ********

1. The storage-life is always certified on certain condions like Teperature, Humidity etc etc

2. As the Tests on products by mnftrs have been slacked for their intrest, deterioration in quality has suffered.

3. Almost all the major manufacturers [all types] are getting products from cheap-labour & under-developed countries' 2nd-Source producers and get their logos stamped to earn much

higher profits & loot the consumer.

4. The "Group" of Cells or "Battery" in real sense need a long Life-tests [in rechargeables] to

ascertain to group = capacity cells in a battery. So no individual cell will be fully discharged or REVERSE-CHARGED which is common problem if a battery is discharge beyond End-piont.

please also see:

Battery Life

<http://globalspec.ip09.com/rd/9z1zjfvk4p01072bf1d7fbu469nftn7bqb160qq3a6g>

(Electrical Engineering

-----------

More links :

1. Theory of Battery

<http://electronics.howstuffworks.com/battery.htm>

http://www.mpoweruk.com/life.htm