Cigarette lighter socket no longer charges phone

Question

I have swapped out the USB cable, the USB adapter, as well as had the socket tested by volt-meter at the mechanic. Everything checks out as normal.

The "charging" icon shows up on phone display, but percent charged goes down from 30% to 29% after about 45 minutes of charging!!!

Any ideas?

[From the comments] The phone charges correctly in other vehicles.

Answer 1

You could have voltage at the socket with only one strand of copper connected so simply testing for voltage doesn't mean there isn't a fault.

How to check for a bad Ground:

• Connect a load to the socket
• Set the multimeter to measure voltage
• Connect one lead to the Ground connection of the socket
• Connect the other lead to a known good ground If the meter reads above one volt you have a bad ground.

How to check for a bad Positive:

• Connect a load to the socket
• Set the multimeter to measure voltage
• Connect one lead to the Positive connection of the socket
• Turn the ignition on
• Connect the other lead to a known good Positive If the meter reads above one volt you have a bad positive connection.

Answer 2

You could perform a voltage drop test. If the voltage is reduced by the time it hits the phone, it might be high enough to trigger the charging indicator, but not actually be able to charge. Explanation of voltage drop test

Answer 3

Just because you are getting voltage does not mean you are getting current. You may have a frayed connection or corrosion somewhere between the car battery and the cigarette lighter that reduces the amount of current delivered to the cigarette lighter.

Also check the fuse for the cigarette lighter port. Make sure it's good, properly seated and that there's no corrosion either on the fuse or in it's socket.

Answer 4

Yiu can get a little inline meter that measures the particulars of the power drawn from the USB cord. If it’s simply not delivering the needed current, that will show.