Sanjaya,

Standard Alkaline "AA" Battery about 1.5 VDC

NiMH and NiCad "AA" Battery about 1.2 VDC

Going from Alkaline Batteries to NiMH or NiCad
Batteries should not produce any bad results other
than slightly less performance.
= = = 6.0 VDC down to 4.8 VDC

However, for a Radio Designed or Set-Up for NiMH
or NiCad Batteries inserting and using Alkaline type
Batteries could cause some possible problems
= = = 4.8 VDC up to 6.0 VDC

If the Radio is Designed to use a built-in NiMH Battery
Recharging Circuit with the installed NiMH Batteries.
Then using an External NiMH Battery Charger should
with NiMH Batteries should not be a problem.

The key 'safety' problem with NiMH Batteries seems
to be when some one tries to Re-Charge them with
a NiCad Battery Recharger. Then they can overheat;
get very hot; start a fire; and/or explode. -But- They
usually only charge up to 1.2 VDC and if they are OK
after re-charging; can be installed into a radio and used
safely. Repeating the process several time may not be
the smartest thing to do...

Be Safe - Be Wise - Use the Right type of Charger
with the Right type of Battery.

~ RHF