Are all rechargable 9 volt batteries still 7.2v?

[daz]

Or do they now make them so they are an actual 9v? Last time i looked was several years ago, but they still were all 7.2 then.

[tedmich]

no battery is 9v for very long:

see Discharge tests and capacity measurement of 9 volt transistor radio batteries at high current, engieering data

Some do like LiPo 9v but they are not cheap

[Enzo]

Not as simple as that.

A simple cell is called a cell. We use the term "battery" improperly when we call a C cell or a AAA cell a battery. A battery is a number of cells connected together. Think of it as the difference between a note and a chord on the guitar.

But a 9v battery is a battery, tear one open and find six cells connected in series. The basic lead acid cell makes 1.5v normally, and six of them makes a 9v total for the battery. That voltage may start to fall as you use it up, but it starts at 9v.

NiCad cells make 1.2v, so six of them totals 7.2v. I think the lithium hydride cells are also 1.2v cells.

We don't use them much in our stuff, but there are also mercury cells, which produce 1.35v a cell.

[MarkusBass]

I've seen several rechargeable batteries that are 9 or 9,6V. They are for use by musicians. For example here: The Best 9V Rechargeable Battery - MetaEfficient
They are build with 8 cells.



Mark

[daz]

I've seen several rechargeable batteries that are 9 or 9,6V. They are for use by musicians. For example here: The Best 9V Rechargeable Battery - MetaEfficient
They are build with 8 cells.

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Mark

Excellent ! I will check them out, thanks.

A second question....how about AA and AAA ? Are they generally under 1.5v too, and if so are there a new gen that give an actual 1.5 like the 9v? I would assume not since they are still one cell where the 9v have gone to 8 to get more volts. (and yes, i knew 9v are made by using 6 1.5v cells)

[Mark Hammer]

Many Alkaline and carbon-zinc 9v come in at 9.6VDC, and I have no problem charging budget ni-cads that ought to peak at 1.2V up to 1.35 or 1.4V. So, the rating is nominal. That doesn't mean, of course, that they will stay very long at that peak voltage, but it does mean that there is no hard and fast 1.2V/cell ceiling that can never be crossed, and everything starts falling from 1.2V.

That said, unless we're talking abut an "overcapacity" cell like the one MarkusBass pointed out, most 9v rechargeables you find in a bubble-pak on a rack somewhere, will have a hard time hitting 9v.