NIHM AA voltage?

Question

These batteries are usually labelled 1.2 volts, and marketed for use in devices that normally would have 1.5v batteries. Will they in fact drive the 1.5 volt devices?

Answer 1

yes
the device will operate at 1.2 volts, go read a book on electric circuit elements

Answer 2

Although it does seem like it shouldn't, yes 1.2 volt NiMH batteries will work in MOST devices that take 1.5 volt batteries. NiMH batteries (and Nicads for that matter) have a pretty flat voltage discharge characteristic. What that means is they maintain the 1.2 volts for most of their discharge cycle.

Alkaline disposable batteries on the other hand, loses voltage as it discharges. Most graphs on battery life use 0.9 volts as the cutoff point.
So 1.2 volts is within the area that the 1.5 volt alkaline battery is supposed to operate in.

However, there are devices that (for whatever reason) specifially state that alkalines and not rechargeables are to be used. You might want to keep that in mind also.

Answer 3

It depends on the device. Alkalines do start out with a nominal 1.5v per cell, but as you draw power from them the voltage will actually show a steady drop, eventually going below 1.2v. Some devices will continue to run well below 1.2v, but others will barely run at that level. NiCads and NiMHs are rechargables that will ride a plateau at 1.2v pretty much from start to finish, so devices that are optimized for 1.2v rechargables (like most digital cameras) will actually get a more reliable current from rechargables than from alkalines. High-drain devices like portable CD players will work better on regular alkalines, since they need the extra juice to power the moving parts.

Also, there are new NiMHs out there that run 1.25v, like Sanyo's Eneloops or Rayovac's Hybrid line, and will resist shelf discharge (they'll retain about 80% of a full charge after a full year instead of losing their full charge after about one month).