I have a USB socket off my ODB port (I know!). it powers my satnav but my question is this: If I turn off my satnav but leave it plugged in to the USB is there any current draw?

Thanks to any wizard out there who can answer this with some authority ;-)

  • 1
    Does you satnav really turn off, or just go into a sleep mode?
    – Jon Custer
    Commented Jun 30, 2023 at 15:27
  • What satnav? When I turn off my phone and then plug it into a USB power supply, plainly it responds and draws current. It is never 'off' unless you remove the battery. Commented Jun 30, 2023 at 20:53
  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Commented Jul 1, 2023 at 14:31

1 Answer 1


Pin 16 on your OBD port will have power regardless of the position your ignition is in. It's always hot, delivering battery voltage and allowing up to 4 amps draw. Pins 4 and 5 are ground.

Whether your satnav will draw current if turned off depends on your satnav. Some satnavs will recharge their internal battery if plugged into a power source, even if turned off.

To be safe I would unplug your satnav when you turn the engine off and only plug it in if the engine is on.

Or you could be like me and get a deep discharge battery for your car. Then it's safe (or at least, safer) to run your electronics off the battery even if the engine is off. A regular car battery can be drained by electronics more quickly than you might think so it won't be able to start your car.

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