Dave Butler wrote:
xyzzy wrote:
Battery life seems excellent so far, I had it on for about three hours
without plugging it in, and the battery meter still showed at least
7/8 charge

Now that's really good news. I was concerned about the number of wires.
If the GPS reception is good on the yoke, and the battery life is good
enough to leave it unplugged, then life will indeed be good.

Not so fast on this one. I turned on the GPS this morning for the first
time after that flight and the battery showed over 3/4 charge, so I
drove into work with it, about a 40 minute drive. Just as I was pulling
into my parking space it complained of low battery and immediately
turned itself off. I turned it back on and the battery meter showed
over 1/2 charge.

Conclusion: Don't trust the battery monitoring software, and don't
expect any real warning of an impending low-battery shutdown.

Btw adding the flight and the drive I figure I got a little over 3.5
hours out of a full battery charge, with the GXM-30 plugged in the whole
time. I guess I can't really complain given Garmin's promise of 4 hours
and Aviation Consumer's observation of 2 hours.