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USB port not charging iPhone

12364 Views 10 Replies 8 Participants Last post by  Cord
Did a search but didn't see anything on this.

I have my iPhone plugged into the USB port in the center console. The iPhone is receiving power, as the "charging" indicator is displayed. However, even after a long drive, the phone's charge amount is only increased by maybe a percentage point or two. The USB port appears to give just enough power to keep the phone at its current level, but not really charge it.

Anyone else notice this?
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I played around years ago with solar powered USB charging and I will connect my testing devices to the Volt and my Iphone and give you some numbers.

One thing to keep in mind is we use blue-tooth linking with cell phones in the car and that uses extra power and add in cell use will be more power.

Getting step rate of charge information from Apple even for hardware developers is not easy.
To get any charge on some older USB-2 ports the phone/pad has to be in sleep mode.

USB power available from the sockets is all over the map as well.
Ok here are some NUMBERS:

The std Apple Iphone wall charger is max of 5 Watts ( 5 Volts -1 amp) for ref the Ipad wall charger is 10 watts ( max of 2 amps)

The Chevy Volt is outputting 4.57 Volt at 0.48 amps which is 2.1 watts at the USB port
As you can see you are getting less then 1/2 the charging of the normal 120v wall charger.

Using a common 2 inch long Belkin power port USB charger I got 5.01 Volt at 0.92 amps or 4.6 watts.

I have seen some power port chargers that go to 2 amps ( 10 watts)

I think we can now say that 2.1 watts charging may not keep up with a smart phone doing too many functions.
Blue-tooth and cell calls and GPS and I guess the normal music function.

I can run some more test on I-Phone 4s doing these function after it completely charges.

Testing using the watts-up inline meter:
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