Electrical – mobile phone direct power

mobilepower

I've got a few HTC Desire A8183's in which I would like to power directly off the wall socket.

I've got a 12volt 1amp transformer which I've put through a voltage regulator to bring that down to the required 3.7volts as stated on the back of the phone. WHen I connect the +3.7 to pin 4 of the phone and ground to pin 1 it doesn't boot.

I know there must be something I need to do with the other two pins. Some people say one is for the temperature of the battery and the other is a batter status indicator or something like that which needs a resistor.

I've tried a few different approaches so far. I've linked 1,2,3 to ground and supplied positive 3.7volts to pin4. This resulted in a orange & green flashing light which means it has detected the battery is over heating. I then tried putting a resistor on pin3 to ground of 82KOhms but that didn't help.

Here is some advice which I've already tried;
http://www.instructables.com/id/How-to-use-phone-without-battery/?ALLSTEPS

HTC Desire A8183

How can I run this phone directly off power?
I still have a working battery which I can use for testing the voltage supplied.

Update

Here are the read outs;

Phone
3&4 = 1M1
2&4 = 1M3

Battery
1&2 = 4K7
1&3 = 690K
2&3 = 20.3 @200M
3&2 = 1.1 @200M

Battery
Pin 1 & 2 = 0V
Pin 1 & 3 = 0V
Pin 1 & 4 = 3.5V
Pin 2 & 3 = 0V
Pin 3 & 2 = 0V

Best Answer

Pin 1: Ground
Pin 2: 4.7K Resistor connecting to ground
Pin 3: NC (If leaving it unconnected doesn't work, add a resistor with a value of about 650K)
Pin 4: 4V (Max: 4.2)

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