Why all AA Rechargeables are 1.2V?

[ldft]

Any idea why all AA rechargeable batteries are 1.2V? Do 1.5 rechargeable AA batteries exist?

 

[nazure]

Not all rechargables are 1.2V per cell.

Where you referring to ni-mh or ni-cad batteries?
These have their nominal voltage at 1.2V, but they are rather old technologies.

Lithium batteries (those used in most handphones and dslrs) are actually 3.6V per cell.

Now, some alkaline limited rechargables are also at 1.5V per cell.

The voltage is determined by the 'potential difference' btw the anode and cathode.
Manufacturers can't really bump up the voltage unless they stack cells or use different materials for the anode/cathode.

 

[ldft]

Not all rechargables are 1.2V per cell.

Where you referring to ni-mh or ni-cad batteries?
These have their nominal voltage at 1.2V, but they are rather old technologies.

Lithium batteries (those used in most handphones and dslrs) are actually 3.6V per cell.

Now, some alkaline limited rechargables are also at 1.5V per cell.

The voltage is determined by the 'potential difference' btw the anode and cathode.
Manufacturers can't really bump up the voltage unless they stack cells or use different materials for the anode/cathode.

Hi ho,

Thanks for the info, and I should have mentioned this in the content and not only in the title, but I am talking about AA batteries. I know that other sizes have varying voltages.

As for alkaline limited rechargeables, please elaborate. Are these in AA size? Or are they some custom size for a specific appliance. If in AA size, where can I get some, also, how limited is the recharging capabilty, as a ni-mh one can be recharged a few hundred times before it dies.

 

[nazure]

Hi,

This should answer your questions on why they are limited
http://www.batteriesdigest.com/alkaline_secondary.htm

Yes, they are available in AA size.

Don't know about specific brands but did see them in supermarkets before (look around).
Not sure how they will perform in digital cams, probably fewer shots
than using ni-mh.

 

[tao]

From what I know, the 1.2V of NiMH has something to do with voltage fluctuations. The nominal voltage is indeed 1.5V, same as Lithium, Alkaline and drycell but the voltage fluctuates anything from 1.1V to 1.4V when it is in use, so average gives you 1.2V+ and thus 1.2V rating.

The voltage fluctuation is also the reason why NiMH is not suitable for use in some devices that are more sensitive to voltage changes, in which you end up getting very poor battery life from the NiMH, when in actual fact, there is still a lot of juice left when you use in other devices.

 

[ldft]

From what I know, the 1.2V of NiMH has something to do with voltage fluctuations. The nominal voltage is indeed 1.5V, same as Lithium, Alkaline and drycell but the voltage fluctuates anything from 1.1V to 1.4V when it is in use, so average gives you 1.2V+ and thus 1.2V rating.

The voltage fluctuation is also the reason why NiMH is not suitable for use in some devices that are more sensitive to voltage changes, in which you end up getting very poor battery life from the NiMH, when in actual fact, there is still a lot of juice left when you use in other devices.

Hi Folks,

Thanks for the inputs. I did a bit of searching and found this: http://www.starbatteries.com/batteryfaqs.html#My device uses

Very informative.

Learned something new today.