In my car I have power converter for the cigarette lighter. This power converter has some 3 USB ports and 2 cigarette lighter ports. I have devices plugged into the cigarette lighter ports. One of which is to power my phone (is left in car overnight).
If the phone has enough power it will power the other devices plugged into the power converter, when the car is turned off. Power is not coming from the car. I know this for certain as the other devices will immediately turn off when i remove the charged phone.
I assume the power from the phone is leaking through the USB cable and into the other devices. This is a problem as I don't want the phone to discharge over-night.
I think putting in a diode on the 5V wire for the USB cable for the phone will do the trick. What requirements do I need in a diode to ensure that I don't cause damage to my phone and allow it charge as normal as possible?