Anybody who knows anything about electricity knows that when it comes to flash light batteries (or more generally for these modern times, dry cells), the important thing is how much “energy” you get for your money. And yet, the packaging for dry cells tells you virtually nothing about this important specification. And there is nothing to indicate why, say, one brand of 9 volt battery at $2.50 may actually be a better value buy than another at $3.00.
Seems to me it boils down to how many watts (unit of energy) a battery is capable of delivering at some standardized rate of discharge. It should be fairly simple for battery manufacturers to include this information on their packaging (you KNOW they know what the values are) and for retailers to label the prices so that the consumer would be able to compare various batteries on their $ per watt rating.
Even in the wet cell arena, such as automotive batteries, such important values as “ampere-hours” and “cold cranking amps” are readily specified, but nary is a price per energy unit seen.
I totally agree. Batteries should have some specs in the labeling just as any other product is labeled to tell you what you are getting. Why they don’t have it I don’t know but it is not uniques to the USA because I have not seen baterries in Europe or Asia labeled that way either and I cannot see any good reason why they should get away with it.
One big problem with that is that the amount of energy that is available is strongly dependant on discharge rate. The high drain batteries such as Duracell ultras will actually last shorter in low drain devices such as radios (not tape/cd players), but cost more. If energy unit pricing was to become a standard, manufactures would have an incentive to make the battery that gives the best discharge at the test discharge rate and dam the rest (design the batteries for the test instead of real world applications).
ALso from consumer reports, several years ago all alkaline batts are aboyut the same with the name brands having at most 10% more capacity then the no-name - as long as it’s fresh, so it may not be all that importaint.
Well, I would anticipate that several “classes” of battery applications would be established such as “High Drain” or “Long Life” and the standardized discharge rate criteria developed appropriately in consultation with the manufacturers. Manufacturers certainly will not abandon entire classes of applications to concentrate on one criteria where they can maximize their $/W number. Otherwise, automobile manufacturers would discontinue all models except the one with the best looking mileage figures.
OK, how about a bump to have this reconsidered. My letter of inquiry to the Federal Trade Commission (who ought to be interested in topics such as this) couldn’t be bothered to even send me an automated receipt/reply. Do the battery manufacturers have enough clout to quash any move by the FTC to impose this kind of accountability?
milliAmpHours is still only a discharge rate. To get energy you would need to multiply by the circuit voltage (Watts = Volts x Amps = Power). Power x time = Energy. Your electric company charges by your energy consumpion as measured by your watt-hour meter.
Am I missing something? Or is it the case that mAH should be just fine for comparing batteries of comparable voltage?
Anyway, the OP is based on a faulty premise, that “important thing is how much “energy” you get for your money”. The important thing is actually how long the battery will power the appliance you want to power. And people have tested the batteries and concluded that in most cases, batteries of similar type will produce just about the same results, mostly because there’s only so much electolyte and other goodies that you can fit in a single cell. So providing an energy rating wouldn’t really accomplish anything, and wouldn’t be accurate anyway, because batteries age in the package.
I 'd prefer clear specifications instead of vague descriptions for dry cell type batteries. Clearly some types are best for high-draw applications, other for low-draw applications. Unfortunately marketing people shy away from clear labeling on the lines of:
short circuit current: … A
capacity … mAh at 1 mA
capacity … mAh at 10 mA
capacity … mAh at 100 mA
capacity … mAh at 1000 mA
fabrication date …
loss of capacity: … % per month for the first … months, %… per month after that
specified values tested by standards … and …
This massive NiMH rechargeable battery shootout over at DPReview is pretty interesting. If nothing else, it shows that rated capacity is only vaguely correlated to real power, and that there’s more than a 50% difference between the best and worst batteries.
Well, full spec sheets with enough information to satisfy everyone in this thread wouldn’t fit on most battery packages (or would make the packages larger and unnecessarily expensive). Some manufacturers do include a single mAh value on the packaging (I’ve seen it listed on some, but I don’t remember which… Duracell, maybe?). They also make full information available on their websites: here’s Energizer’s and here’s one for Duracell; the spec sheets include things like lifetime for various loads. Making the information available on request seems like a fair compromise here.
Well, I don’t want to have to stand at the battery counter analyzing a bunch of spec sheets that the manufacturers wll make as confusing and dissimiliar as possible. I simply want to be able to see a “unit price” of say, 20 cents per watt-hour for battery “A” and 22 cents per watt-hour for battery “B” and reach the reasonable conclusion that I’m getting a better bargain with battery “A”, other factors such as design discharge rate or suitability-for-purpose being equal. Is this too much to ask? After all,doesn’t everyone buy toilet paper on the basis of its price per square foot?