Disposable AA batteries are always 1.5V. BUT......?

Question

Disposable AA batteries are always 1.5V. Rechargeables are ALMOST always 1.25V only. WHY?

Answer 1

Alkalines only give 1.5 for the first few minutes, they slowly start draining until 1.0v when they are used. The average output is about 1.25, same as a rechargeable. They both Give the same average output, rechargeables keep pumpin' the 1.25v until tha last few minutes where the lower quickly. REchargeables are better outputwise. alkalines slowly drain, Rechargeables don't really drain until the very last few minutes of use.

Answer 2

Well, sort a... carbon zink and alkaline batteries are about 1.5 v, where as Nicads are only 1.25v. That is why in 12v hand held walky-talky's it takes 10 Nicads and only 8 Alk.'s. the new Metal Hydroxides however, are close enough to the 1.5 spec to replace non-rechargeable batteries in such things as cell phones and digital cameras and have much higher Mah ratings.

Answer 3

That's the way they are, but the AMP HOURS are different.

Alkalines can't take a drain (and they drop in voltage as they drain).

You can use them up in a camera and they'll still run a flash light or a walkman.

Lithums have far better amp hour life.

From where I stand

Alkalines seem to have 1.25 V 200 Milli Amp Hour
Recharable have 1.25 V 2000 MAH
Lithums throw aways have 1.25 volt 10,000 MAH

I get 7 pictures with Alkalines, 50 with NIMH and I'm told Lithums give about 200

Answer 4

It is down to the chemistry.

Each material has an electrolytic potential, when you put two together, you get an electrolytic potential difference (voltage).

It is the electrolytic action that promotes rust at holes in Chromium plating of steel. Water is the electrolyte in this case.


Disposable batteries have a carbon - zinc reaction which has an electrolytic voltage of 1.5V.

'Alkaline' batteries are carcon - zinc batteries built inside out and inside a steel shell. This is the same electrolytic voltage.

Rechargeable batteries -

Lead - acid has a EV of 2V

Nickel - Cadmium has an EV of 1.2V

Nickel - Metal Hydride has an EV of 1.2V.

Answer 5

It just depends on the chemicals in the battery. Lead acid car batteries just happen to generate 2V per cell. Alkaline 1.5V, NiCad and NiMH 1.2V. Lithium Ion is 3.6V per cell, which is why there will never be a AA Lithium Ion (Not to be confused with disposable lithium at 1.5V per cell) So you see it all depends on the voltage produced by the reaction of the particular chemicals in use.

Answer 6

That is beacause it needs to be that way to charge. Its very hard to explain, but thats the way it is.