SDStaff Ken contradicted himself by saying:
and then immediately following this up with:
In the first quote, he says “no chemicals are reacting” while the battery is in storage. In the second quote, he says that chemicals are reacting while the battery is in storage.
I believe it would be more correct to say that chemical reactions are occuring within a battery at all times. When in storage (not under load), the chemical reactions happen at a much slower rate, but do not stop.
-m
Being an absolute idiot when it comes to chemical reactions, I can only point to practical experience.
Whenever I had to do with batteries, I made the experience that cold temperatures let them bleed out faster. Actually, that seems to be the point of all those battery warmth pouches that come with headlamps for mountaineers (my bad English and my fatigue really shine through, sorry).
Also, I have read ‘somewhere’, that if you throw batteries into hot water, you’ll get still some energy out of old, previously presumed ‘dead’, ones.
Doc
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Should you refrigerate batteries to make them last longer? (15-Mar-2001)
Consumer Reports did a five-year test comparing batteries stored at room temperature with those stored in a refrigerator at 37.5 deg. f. The result? “Refrigeration, we’ve found, only very slightly extends shelf life.” (December, 1999).
Don’t you think that the energy you “save” by refrigerating them is vastly offset by the amount of energy it takes to actually keep them cool?
Here’s an example to put that in perspective:
I’m going to build a solar car. The solar cells will charge batteries when my car is parked in the sun, and I’ll still be able to drive it an night. But, to “keep the charge longer” I’ll run a refrigeration unit on the batteries.
Steve
IF the refrigeration unit were only being run for the sake of the batteries, sure, slacy. But if the refrigerator is on anyway, the incremental cost of putting the batteries in the refrig has to be pretty much negligible – even if you include the extra energy to open the refrig door to take the batteries out.
I used to design sonobuoys, which are free-floating listening devices the Navy uses to detect submarines. Sonobuoys have a float that must be automatically deployed and inflated. In our design, we had the following system: buoy drops in the water, water pressure turns on a switch, which connects the circuit from a battery to a squib (small gunpowder charge). The squib fires, driving a hollow pin into a small CO[sub]2[/sub] bottle. The bottle empties into a float, which is held in place by a plate. The expanding float blows off the plate, usually violently, and the float surges to the ocean surface. Got that?
Anyhow, we were doing “cold float tests” to see if this system would work when everything was ice cold. A real system uses lithium batteries, but for this cold test, I substituted cheaper (and more stable) alkalines…which are also, apparently, more susceptable to cold. So we tied a string onto the switch (to manually activate it) and dropped the bouy into our test tank. I pulled the string to flip the switch, and…nothing happened.
Now a failed test usually isn’t a big deal, but in this case, the buoy might suddenly activate at any time, blowing off the top plate. Much better to have that happen away from engineers like me (and remember, we weren’t sure just what went wrong). The only way to turn thing off was to raise the buoy and manually turn of the switch. We stood around for a while debating what to do, until the problem was solved for us a couple minutes later by the system suddenly working and the float appearing at the top of the tank. Whew. We later decided it must have been that the battery was too cold to produce enough amperage to blow the squib, until it eventually warmed up enough. We changed the testing procedure after that.
The point of this story: different types of batteries have different susceptablities to cold temperatures.
Dr Ennig:
There seems to be some confusion about the purpose of hot & cold temperatures. Here’s the scoop:
In most chemical reactions, heat speeds it up, cold slows it down.
So, in a general sense, a cold battery can supply less “juice” but will last longer; a warm battery will supply more oomph but self-discharge faster.
This explains why mountaineers may want to carry batteries warm to be ready for immediate use. If they planned to be in the cold mountains for months, they might not care.
Duracell – our batteries have more Juice to the Oomph! 
While it may be true that only a small amount of power is saved by refrigerating batteries, here is an important point about refrigeration itself: The more you have in your fridge, the less energy is required to keep it cool. That is, an empty refrigerator uses the most energy whereas a completely packed one uses the least. This is just the nature of refrigeration. This alone should compel you to put anything that could benefit from being in there, in there. Batteries, or film or water or whatever.
Here’s the reason why cooling batteries doesn’t noticably extend their shelf life:
So far we’ve touched on the point that as a battery is cooled it’s potential (voltage) is lowered. The chemical reaction can only occur in the battery if the electrons can get from one end to the other. The potential of the cell is what pushes the electrons there.
But in real life a battery doesn’t just behave like a voltage source. It behaves like a voltage source with a resistor across the terminals. This is what causes self discharge. Don’t ask me where this path for the electrons to flow exists physically, I’m not a battery engineer. My guess would be impurities in the materials.
Most conductive materials conduct better as it gets colder. There are very few exceptions.
So - as it gets colder the battery has less oomph to push the electrons around the conductive path - but the path now has less resistance, making it easyer for the electrons to get where they are going thus allowing the chemical reaction to continue at close to it’s original pace.
There is obviously some temperature where the two factors (potential vs. resistance) come together favorably to give the longest shelf life. But I have to believe that it won’t affect my daily life as much as the fact that I have to warm up a battery out of the fridge just to use it (at full power anyway).
Joe
The reason that we keep our batteries (and photographic film as well) in the freezer is not so much that it extends their lifespan (as previously stated, it does, but for batteries not that much), but rather that it makes them easy to find!
The freezer is a good place since it is relatively easy to search and otherwise the film and batteries would be stuck in some drawer somewhere and we would have the problem of trying to find them.
My current problem is disposal of old batteries - I keep a bunch of them on the corner of my desk as they slowly build up over the years, what with smoke detectors, PDA’s and other little electronic do-dads. The plan is to dump them off at Radio Shack or a similar place for proper environmentaly sound disposal or recycling, but I never get around to it. I know that modern batteries use less of the bad stuff that we want to keep out of our landfills, but I figure every little bit helps. I know that Ni-Cad batteries are particularly bad and should not be thrown out with the rest of the trash.
Does anyone know the preferred method of battery disposal?
Strange sort of physics in your kitchen, e433. On what law of physics do you base your assertion?
And how full must the fridge be before no energy at all is needed to keep it cool? Would a dozen 6-packs be enough?
Here’s the real dope on batteries:
Loong ago, abck before 1970 or so, the most common kind of “battery” used by the average bozo was the carbon-zinc cell. There were a very few Alkaline and mercury cells,
but 95% or more were the carbon-zinc kind.
These kind were, to say the least, lousy. They only lasted a few months at room temperature. The chemicals inside would quickly attack the zinc, spewing out a few teaspoons of orange acidy liquid.
If you’ve ever opened up an old flashlight or toy and found a rusty-looking orange mess, that was a carbon-zinc cell.
Now THOSE you could extend the shelf-life of by keeping them cool.
Around 1970, the powers-that-be decided it was time to stop hiding alkalines. Alkaline cells use a completely different chemical reaction than carbon-zinc cells. Not only do you get much more current out of them, they don’t self-destruct as quickly. You can keep alkalines on the shelf at room temperature for years without them consuming themselves.
Carbon-zinc cells are still sold-- they’re usually labeled “for normal use”, meaning not heavy-duty.
So there you have it-- everybody was at least partially right. Take a time-machine back to 1960, or buy the “normal duty” cells, and yes, you should keep them in the fridge.
Buy alkaline or lithium cells, and it won’t make much difference what you do.
Regards,
George
The original question was obviously about D, C, AA, or AAA battery cells that can be purchased in stores everywhere. These are primary battery cells, and they will retain charge for several years after manufacture at room temperature as shown by the “use before” date on the package.
Some of the replies in the thread mentioned nickel-cadmium battery cells. I will expand on this topic a bit.
Nearly every spacecraft flown has contained large secondary (rechargable) batteries composed of (typically) 24 cells connected in series. (The exceptions were those powered by RTGs [radioisotope thermoelectric generators] or hydrogen-oxygen fuel cells.) There are two principal types: nickel-cadmium and nickel-hydrogen. Besides the nickel positive electrode, the aqueous potassium hydroxide electrolyte is common to both products. The respective negative electrodes are cadmium and hydrogen–the latter enabled by a platinum catalyst. Self discharge is a significant feature of both cell types. In space, low rate trickle charge is applied after the battery is fully charged to overcome this tendency. Standard design practise requires that flight batteries be charged at sunlight average cell temperatures between 41 F and 50 F using various passive techniques. No “refrigeration” is necessary.
These cells are stored on the ground individually or as battery assemblies at 32 F. Both types are fully discharged; the NiCd cells are short circuited and the NiH cells are open-circuited. In keeping with this theme, I store my camcorder battery in a ziplock bag in the bottom drawer of the refrigerator. However, in general, other commercial battery types do not require such special attention.
Self-discharge is real and not mysterious. It’s not true that there is no loss of energy from a battery in storage, with it all remaining potential. There are conduction paths between the anode and cathode at all times, consisting of the air around the battery and the insulating material in the battery casings. True, these paths have very low conductance compared to any device the battery would normally be installed in, but their conductances are not zero and they will have an effect over time.