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Does a USB port draw current if not in use?

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I recently put a combination cigarette lighter and USB plug on both of my adventure bikes (CRF450X and TTR250) to run the GSP on rides.  Not wanting to mess with the stock electrical system, I ran new wires (obviously fused at the battery) from the battery to the front of the bike.  In doing that, I did not put an on-off switch in line, thinking that as long as I take the GPS off after every ride and nothing is hooked up, there should not be any current draw.

Oddly, since doing that, if I leave my bikes for a few days, the batteries are dead or much lower than they were before.  Granted it is a little colder now (45 vs 65 degrees at night).  I'm sure a cigarette lighter does not draw current with nothing plugged in, but I really don't have experience with a USB plug.  Could it possibly draw current?  I do keep one end of the GPS cable plug plugged into the USB connection, but the other end at the GPS is not connected when the bike is sitting up.   And, yes, the Honda battery is brand new, and the other battery is good too.   I could have easily left them untouched for a week before this and they would have cranked easily.    Any ideas what might be going on?   Thanks!

I know that my (active) guitar which is battery powered does draw power as long as it is plugged in, whether or not I am using it.  Maybe the USB plug is the same way???

 

 

 

Edited by JCW

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If the USB is powered up all the time (nothing plugged into it, just 'live') they still have a parasitic draw. They take the 12.8 volts from your battery and convert it to 5.2 volts.

Every plug a power adapter in a wall outlet, yet never connect anything to the other end, then remove the 'wall wart' later to find it warm? It was sucking up power and not outputting.

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Thanks for the reply.  It's time to change it to a cigarette lighter only plug, or put a switch in line.  I appreciate the reply and info!!

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2 minutes ago, JCW said:

Thanks for the reply.  It's time to change it to a cigarette lighter only plug, or put a switch in line.  I appreciate the reply and info!!

That or put it on the already switched line on the bike. The draw is small and you will not over load existing electrics. Though of your choices, the switch is better as it will not be as much of a  fail point (use a water proof switch)

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