[coathangers]

Does the rear window defroster turn on and off with ignition, or will it draw power if there is a circuit?

I bought a 12v converter that outputs 3 amps into 2 female usb ports, which I want to use for my dash cam and general accessories. I want them off when ignition is off so to not drain battery.

I got a fuse tap for the ATC size fuses, with a 5 amp fuse, now I'm stuck because all the posts here say I need to use a mini blade fuse tap and tap into the cigar lighter.

I just want 12v that switches on and off with the engine. On my model of car it has a very specific fuse box. On the link below I have the E90 type 2 fuse box, and the window defroster is F46 (30 amp ATC size, the circuit doesn't need more than 20 amps I think, so it wouldn't overload with an additional 3 amps).
https://fusesdiagram.com/bmw/fuse-bo...bmw-3-e90.html

Is it advisable to piggy back the rear window defroster here, or should I get the mini tap first and follow the forum?

Can I even use one of the unused fuses and plug in a spare fuse?

Thanks

[coathangers]

Originally Posted by coathangers

Does the rear window defroster turn on and off with ignition, or will it draw power if there is a circuit?

I bought a 12v converter that outputs 3 amps into 2 female usb ports, which I want to use for my dash cam and general accessories. I want them off when ignition is off so to not drain battery.

I got a fuse tap for the ATC size fuses, with a 5 amp fuse, now I'm stuck because all the posts here say I need to use a mini blade fuse tap and tap into the cigar lighter.

I just want 12v that switches on and off with the engine. On my model of car it has a very specific fuse box. On the link below I have the E90 type 2 fuse box, and the window defroster is F46 (30 amp ATC size, the circuit doesn't need more than 20 amps I think, so it wouldn't overload with an additional 3 amps).
https://fusesdiagram.com/bmw/fuse-bo...bmw-3-e90.html

Is it advisable to piggy back the rear window defroster here, or should I get the mini tap first and follow the forum?

Can I even use one of the unused fuses and plug in a spare fuse?

Thanks

For example I have empty fuse sockets for the following circuits:

x3 Trailer control module (30 amps each)
x2 Seat Adjustment control module (30 amps each)
1x Head lamp washers (30 amps)

I won't be buying a trailer, new seats or head lamp washers, so is it a good idea to use those instead? Or will that damage the car somehow?