Thanks, Bill. I have a fast, 'smart' charger so I'm going to try it. And
thanks for the explanation about the low battery indicator - very useful
information.

- Rob Malkin


wrote in message
...

I have a Garmin 725 handheld that I use as a backup. The nicad pack
was never very good. Garmin has a NiMH pack as an option, and they
claim it would run the radio for 10 hours. They wanted EIGHTY
DOLLARS!!! I loaded up the extra battery bracket with 6 1850 milliamp
AA NiMH batteries that were freshly charged up. The radio's battery
indicator initially read 1/2 charge, and the indicator soon changed to
flashing "low battery", but the radio ran for over 21 hours that
way!!!

The reason for this is the threshold setting in the radio. NiMH
batteries have only about 1.2 volts each when fully charged, unlike
standard AA cells which are 1.5 volts. The difference is that the NiMH
cells stay at that 1.2 level for a long time before steeply dropping
at the end of their duty cycle. The indicator on the radio was
engineered to work with batteries that start at 1.5 volts and
gradually, but constantly, output lower and lower voltage.

Bottom line? Try it. The only thing I would warn against would be
using the "dumb" charger that came with the radio, or any 12 volt
adapter cables. For NiMH batteries it is very important to have a
charger that shuts off automatically when the batteries are charged.
Otherwise the batteries will get VERY hot, and possibly start a fire
in addition to self destructing.

I have a fast charger designed for the NiMH batteries that runs off of
either AC or 12v DC on the boat. I use the same size batteries in my
GPS and my digital camera, so there is always a set being charged, and
plenty of fresh spares to rotate.

BB