HTC Desire S keeps turning off

I’ve had my HTC Desire S (S510e aka Saga) since May 2011 and it has been an amazing phone. I’ve upgraded it to ICS and use it constantly. All of a sudden it started turning itself off – not rebooting, but losing power. There were a number of other people who had the same problem but no solution.

This was incredibly frustrating, so I tried a few things:

• factory resets
• different charger
• no microSD card
• no SIM card
• S-OFF, changing the recovery and rooting the phone

Eventually I was able to get a stable phone by leaving the SIM card out. As soon as the SIM card went back in it would power off. Then I discovered you can log the debug output from your phone using adb logcat on your computer. You can follow some of the instructions and downloads from CyanogenMod’s Saga install instructions (up until using adb for the first time). My log output contained lots of stuff until shutdown with nothing too obvious, so I worked my way backwards and found something quite interesting:

D/HtcPowerSaver( 1584): Checking...
I/HtcPowerSaver( 1584): >> updateStatus
D/BatteryService( 1584): updateBatteryStats ======================================
D/NotificationService( 1584): mIntentReceiver() Intent.ACTION_BATTERY_CHANGED
D/PowerManagerService( 1584): runHtcPowerSaverCheck ======================================
I/HtcPowerSaver( 1584): currentStatus=8000, currentLevel=68, enableLevel=20, enable=false, popDialog=false, statusChangeTo=-1
I/HtcPowerSaver( 1584): << updateStatus
D/WifiService( 1584): ACTION_BATTERY_CHANGED pluggedType: 2
D/PowerUI ( 1678): closing low battery warning: level=68
D/PowerUI ( 1678): plugged = true, health = 2, mBatteryLevel = 68, mPluggedBatteryLevel = 68, mLowBatteryWarningLevel2 = 25, mshowLowChargingWarning2 = true

I had previously bought a new battery and charger but nothing else had changed when it started to misbehave. It looks like the HTC battery may have failed slowly or with the introduction of another charger. Installing a different third party battery from eBay seems to have solved the problem. I hope this is helpful for anyone else suffering the same problem.

Thank you HTC for allowing people to S-OFF their own phones.