In article 441809da.0@entanet, Zog The Undeniable wrote:
Pete Biggs wrote:
Zog The Undeniable wrote:

LEDs are also generally awful when run from NiMH cells.

"Nickel Metal-Hydride batteries have a high capacity and a very flat
discharge curve which maintains a cell voltage of 1.2V over ~80% of the
discharge curve. This gives a nominal pack voltage of 4.8V which as you
can see from the graph brings the mean efficiency up toward 70% and since
the fully charged voltage of the pack is only 5.6V the maximum LED power
is about 1.3W for a brief period and stays at 1W for most of the discharge
cycle. If you do not want to modify the light I strongly recommend you use
NiMH rechargeable batteries, you will get much longer run times."
- http://www.ajjrice.plus.com/reviews/smart%20nova.htm

Yes, but LEDs are more voltage dependent than current dependent.

Well, sort of, in a way, ignoring lights with proper regulation (which
should be current regulation for LEDs, not voltage regulation).

But while the lower internal resistance of rechargables isn't as
significant at the typically lower current requirements of LED lights
compared with incandescents, LEDs are more efficient at lower currents,
so a small amount of undervolting won't reduce brightness anything like
as much as it would for an incandescent.

Any LED light that is ok on part-used alkalines should be fine with NiMH.