> I don't trust rechargeable batteries (they don't have the strength as
> alkaline batteries).  I change my batteries when the power drops under
> 50% on my etrex battery indicator.

While the NiCds of old were definately sub-standard, modern NiMH perform
similarly to alkaline batteries in high-drain devices like handheld GPS
recievers and pocket computers.

First off, the average "AA" alkaline battery has about a 2600 mA/hour
rating.  "Enhanced chemistry" alkalines, like Energizer's "e2", have about
a 3100 mA/hours.  While the old NiCds only had about 700 mA/hours of
power, the new NiMH rechargables well exceed 1500 mA/hours. I've even seen
2000 mA/hour NiMH "AA" cells, which is getting real close to a low-end
"cheap" alkaline.  (For reference, Eveready claims their commercially sold
NiMH "AA" cell is rated at 1850 mA/hours)

But that dosen't tell the whole story.  One of the nice things about a
NiMH battery is it performs as well, if not better, under high drain than
an alkaline.  While they don't have the nice clean linear voltage drop-off
that an alkaline has, they do provide adequate warning when they are
running out of gas (one of the primary complaints of NiCds was they had a
severe dropoff as they died, giving little if any warning of impending
failure).  Also, NiMH batteries seem to perform best in the exact kinds of
loads one would expect with a handheld device: hard, heavy draws to 60-80%
of charge within a short period, and reasonably quick recharge and reuse. 
NiMH batteries hate sitting in a drawer not doing anything.  In fact, one
specsheet I have for NiMH cells states that optimal mA/h performance is
seen after 10-15 charge/discharge cycles.

I use NiMH batteries in darn near everything.  They work, and work well..
and I've never been in a position where I've been without power.  I carry
a set of AA alkaline batteries in my "cache backpack", and they've been
sitting in there for a year unused, because the NiMH batteries are strong
enough to last an entire day of use in my reciever.

-- 
C. Sullivan               the world needs more mayo
feedle@feedle.net         www.moremayo.com
Phoenix, Arizona USA      another boring blog site.