Power on nav and aux with booster pack plugged in

[DeltaT]

I have one of these:

It not only works as a booster pack but also has a little compressor to top up my tires. I have been using it quite often helping others this winter so I thought it would be a great idea to carry it around in the back of my hundy. I wanted to leave it plugged in using the plug in the trunk so it would always be charged.
But I noticed that if I turn off the vehicle (and take out the key) both the navigation and the aux plug (in the dash) are being powered by the booster pack. And they stay on unless I disconnect the charger cable from the booster pack.

Does anybody know if there is such a thing as a 'one way' plug adapter that ensures that the pack gets charged but doesn't power the vehicle.

 

[hankinid]

Does anybody know if there is such a thing as a 'one way' plug adapter that ensures that the pack gets charged but doesn't power the vehicle.

Sounds like something using a diode...allowing current to the pack and blocking current from it back to the main battery.

Maybe e-trailer.com?

Shouldn't be rocket surgery to find a diode and some heat-shrink at Radio Shuck...you'll need to know the maximum current the pack pulls.

hth

Steve