[EVO 4G General] PGRtoo:
Here are my observations:

The Evo seems to have a peculiar way of using external power. Once the battery reaches full-charge the external power apparently gets shut off and the phone operates on battery power until the battery level drops to somewhere around 85-90%. Then the charging current switches back on until the battery level reaches 100% again and the process repeats itself. This differs from more conventional scenarios where the phone actually runs on the external power (rather than the battery) once the battery reaches full charge.

I came to this conclusion while playing with my Evo while it was plugged into the charger. First I noticed that the charging light would cycle from green to amber and back every so often. Then I noticed that the battery level indicator would drop even while the charger was plugged in.

So I started checking my battery level in the morning before I removed the phone from the charging dock and discovered that it was rarely at 100%. I'm convinced that the phone does get charged to 100% when I put it on the charging cradle, but then it sits there running off of the battery until it drops to that magic ~85-90% level and the charging current is reestablished.

But a typical night on the charger isn't enough time for the battery level to drop enough to re-start the charging current and if I come along and just grab the phone, I'm starting my day with a battery which isn't completely charged. In my case, the only time this doesn't happen is if my day ends real late and the next morning starts real early.

Once I had a good idea of what was going on, coming up with a work-around was simple: One of the first things I do when I get up in the morning is look at the charging indicator on the phone. If it's amber I do nothing because the phone is already in charging mode. If it's green I remove the phone from the cradle for a moment and put it right back on. Most of the time the indicator will switch from green to amber when I do that, but if it doesn't I'll go online and read the news or something for a few minutes before I put the phone back on the cradle.

Either way, the phone will then charge for 30 minutes or less before the indicator goes green again. By then I'm done with my morning routine and ready to face the day, and when I grab the phone it's fully charged.

My Evo is out-of-the-box stock (for now). It's a hardware version 0003 and has firmware v. 3.29.651.5. I typically leave my Bluetooth turned on all the time, but I leave 4G, WIFI, and the GPS turned off unless I need 'em. My typical daily routine involves several phone calls, some email downloads and uploads, some incidental web browsing, and some geocaching if a new cache is published within a few miles. As long as I stick with that typical routine, my battery is always in the 40-50% range when I put the phone back into the cradle for the night. Of course if I use the phone more it discharges the battery more, but I'm set up to charge it at home, at work, and in the car.

Now despite everything I've posted here, I can't imagine any practical reason to not top off the battery whenever it's convenient. Letting the battery run down before you charge it doesn't have any effect on how long a full charge will run the phone. In fact, it will actually reduce the number of charge-discharge cycles that your battery can provide before it starts losing capacity. I don't want to type it all again, but if you're interested you can CLICK HERE if you'd like to learn more about LiPo battery characteristics and maintenance.

'Nuff outta me

Pete