What is the difference between D, C and AA batteries? They are all listed as 1.5 volts. Could you use a AA battery to operate a toy, or what ever, that requires a D battery? 
You can.
Size = capacity. That’s it.
They are all different sizes
SIZE VOLT. DIAM. HEIGHT WIDTH
D 1.5 1.346" 2.421" N/A
C 1.5 1.031" 1.969" N/A
AA 1.5 0.571" 1.988" N/A
9V 9 0.689" 1.909" 1.403"
AAA 1.5 0.413" 1.752" N/A
AA batteries might work where D batteries are called for in a toy, but not with the same oomph. Even though a AA battery and a D battery are both 1.5 volts, D batteries deliver higher current and wil last longer because they store more energy.
To expand on what has already been posted, it comes down to amp/hours. The battery for my snowblower is 12 volts, as is the one in my truck. The difference is that the snowblower battery has a fraction of the ability to deliver a steady draw of x amps over time that the truck battery can deliver.
It’s more than just capacity. Another important difference is that larger batteries usually have much less source resistance. This means a fresh 1.5 volt D battery is able to maintain a higher voltage for a given load when compared to a fresh 1.5 volt AA battery. Using Ohm’s law, this also means a fresh 1.5 volt D battery is able to maintain a higher current for a given load when compared to a fresh 1.5 volt AA battery.
Just to nitpick.
The AA, AAA, C, and D sizes are CELLS, not batteries. Batteries consist of sets of cells. The 9 volt however is a battery because it has seven small cells inside the casing.
In the context of the OP, he need not concern himself with anything beyond size = capacity and he can use a 1.5 C battery to power something that is sized for a D.
The C battery will dropped dead alot faster, and that is pretty much the essence of the answer.
Six. It has 6 x 1.5 V AAAA cells inside, if we’re talking about an alkaline 9 V battery. Some NiCd 9 V batteries do have 7 x 1.2 V cells for a total of 8.4 V, but most have 6 x 1.2 V cells for a total of 7.2 V. The 8.4 V “9 V” batteries are much more expensive because they use a series stack of non-standard oddly shaped cells (picture a 9 V batter sawn into 7 crosswise sections), rather than the standard AAAA size inside alkaline and 7.2 V NiCd Batteries.
The one I disassembled was a NiCad. Guess I should have done a comparison.
Radio Shack used to sell, and maybe they still do, a set of sleeves to “upsize” their NiCads. You slipped a C sized cell into a D sized sleeve. Don’t recall if they accommodated the AA sized cells.
As a slight hijack, I used to have a “F” sized NiCad cell. It was a fine unit for glowplugs on model airplane engines. Heck of a large cell. IIRC it was rated about 4 AH. It’s been years ago and I’ve never seen another one.
This isn’t terribly relevant, but I thought I’d throw it in.
I remember reading once that consumer reports or some similar magazine bought a bunch of “D cell batteries” of various brands and had them sliced open (taking all sensible safety precautions)
Over 70% of the batteries that were tested actually had C cell power sources, just surrounded by a thicker casing so that the resulting battery was of the right size to fit into a D battery slot. :]
I have one device that is powered by an AAAA battery* – a stylus for a touch-pad. (It was the first time I had seen an AAAA battery, and I actually tried shoving an AAA into the pen because I couldn’t find the included AAAA at first.) Could I use one of the AAAA cells from a 9V battery instead of buying a pack of AAAA batteries, if I didn’t feel like buying AAAA batteries?
*: Yeah, cell, I know.
Three times I’ve pulled open alkaline 9V batteries, and neither time did I discover anything that looked like AAAA cells. What gives? What I found was a set of six black tabs stacked atop each other, with a bit of a gluey substance between them. They were not cylindrical, but rather rectangular, following the shape of the 9V battery.
Read QEDs post #9 above. I think you’ll find the answer.
I did.
So I take it these batteries I’ve pried open are the 8.4V “9V” batteries? I don’t remember seeing seven cells, but rather six, and the batteries were certainly not Nicads.
Huh. What brand were they? Are you sure they were an alkaline formulation? It’s also entirely possible that manufacturers are phasing out the AAAA conficuration. It’s been a few years since I pulled one apart.
chrisk: I believe, in fact, that the Consumer Reports article stated that all the D-sized NiCd cells they cut open (4 or 5 different major brands, IIRC) were a C-cell in a D case, with the sole exception of the Radio Shack D-size. I worked for Radio Shack at the time the article was published, and believe me, we made the most of it.
Where they actually C cells inside the cases, or were they merely C-sized cells in there? If so, I don’t see the problem - especially if the AH rating was given.
They may not nave been labelled, but it was nevertheless clear that the manufacturers were using their own C cells to make Ds to same money. This practice has largely stopped, anyway, making it irrelevant.
This goes even further and weirder when you compare different battery chemistries in high load devices. Alkaline and carbon zinc cells nominally deliver 1.5v while NiCad and NiMH are 1.2v. This is when measured with a meter with high impedance which places a tiny load on the battery. High current devices such as photo flash will actually have a higher voltage drop and consequently more current flow from the 1.2V NiMH/NiCad cell than a 1.5v alkaline. This extra current flow is usually an advantage but Metz includes a warning not to use NiCad/NiMH cells in the alkaline pack for the 45 series flashes as the higher current flow can burn up wiring. There is a factory NiCad pack but it uses a different positive contact that is configured in the flash to accomodate those cells.
NiMH also has a very different discharge curve than alkaline as it maintains most of it’s voltage until nearly discharged where alkaline loses voltage in a more linear fasion as it discharges.
Maybe. I dissected a Duracell 9V battery. The cells are connected by thin steel strips that are spot-welded (?) onto the ends. The strips can be mostly peeled off, but a small piece remains. This piece could be ground off, or perhaps left on as it might not be a problem. The positive end of the cells was simply the steel cap of the cells’ body, while the negative terminal had a tit. This is the reverse of the layout on AAAA cells sold as such, and may or may not be a problem depending upon whether the device is polarity-sensitive.