I'm skeptical of stern recommendations to users to not charge all the way (which is tricky ... whaddya do, set an alarm to wake you up in the middle of the night while it's chargin?). I've been watching the performance of several chargers on my Amaze compared to the HTC charger. All the chargers are technically capable of 1000mA charging, but on the HTC charger, the phone takes up to 908mA (well, as displayed by Battery Monitor Widget). The Apple iPod charger doesn't show up as an " AC Charger" because Apple puts reference voltages on the D+ and D- lines that iPods recognize. Most devices recognize a direct short on the data lines to indicate the USB connection is a charger only, not a computer USB port (which is limited by the spec to 500mA, available in steps of 100mA). Another Duracell charger provides about 400mA - 600mA.
The charging records indicate that the HTC handset is intelligently governing the charging rate. As it nears 80%, 90%, and 100%, the measured current is reduced. Even if the mA gauge is not getting the data correct, look at the RATE if increase over the two-minute measurement intervals (the Y, or time, axis of the charts) ... it slows down a bit. Both images are from overnight charge cycles, with screen turned off. Autosync and other periodic processes are disabled at night by Llama. Vertical indices represent one hour.
The top slope (last 10% of charging) seems shallower on the stock HTC charger than on others. I couldnt' tell you why ... I don't want to dismantle one to see if there are some intelligent feedback circuits in there in addition to the voltage conversion basics.
Battery Monitor has alarms for "Battery Full" and "Charging complete" and the "full" alarm follows the 100% by several minutes. The "charging complete" alarm has been as much as 20 minutes later. So if those alarms are triggered directly by phone indicators, then clearly the charging circuit is managing the charging process.
My take-away from this: I don't think you have to protect the phone from itself.
Last edited by ChromeJob; 03-24-2012 at 09:23 PM.
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