Step down transformers.

[Sloppysod]

i am adding three USB sockets to my car, to power phones and a tablet, however, i have rin into a problem.
no matter where ever i add a fuse jumper the usb sockets remain live after ignition has been switched off! not asvi had planned/wanted. i have tried a fuse jumper in both electric front seat positions (G38 & G39) and even Sunroof (G34) which i dont have, with the ignition off, the seats don't work but the USB's will still charge.
is it possible that these step-down transformers have residual current and will take time to empty?

[GiveMeABreak]

Hi Stu, check out my dash cam install here which I updated some time ago regarding fuses:

viewtopic.php?t=56750

Search for the "Switched Live" in the post section (28) for info:

I think for the ignition switched fuse I used F4 (10Amp) for my dash cam.

[Sloppysod]

thanks Marc, yes you had the same problem, not turning off as expected
F4 it is.

Ok, so Fuse F9 is the one arrowed in Red and is 30 Amp for the Cigarette lighter.



Remember that this is permanent live at the fuse box, but the cigarette lighter itself is switched off by the BSI on economy mode or after a certain amount of time. This was no good for my setup, as the dash cam obviously stayed on for quite some time after I left the car - and if you don't manually switch the dash cam off it will stay on and gradually drain the battery over time.

I used Fuse F4 just along to the right in the picture above. This one is for the "Automatic gearbox - additional heater unit (Diesel) - electrochromatic rear view mirrors" This one is switched positive.

EDIT Jan 2018:
Main Article Updated for Permanent Live and Switched Live options

[GiveMeABreak]

No worries, will save a flat battery for sure!