Adding a 12v outlet (1 Viewer)

[markthegrea]

So there are lots of threads about this but I have a question that I don't think anyone has asked. I have an Add-A-Circut and understand the load and the breaker side. All that is fine.

Here is my question:
If I use any 10amp circuit and I add a circut to it, if both circuits use 10amps at the same time, won't that overload the vehicle wiring?

An example: If the headlight circut uses 10amps and I piggyback on it for 10 amps for this socket, won't that possibly draw 20 amps when I turn the headlights on and wouldn't that be a bad thing?

If this is the case, how could you ever add a circut? Don't we have to assume that all circuts could draw the maximum amount?

 

[Sky Soldier]

Yep. Both circuits pulling 10 amps at start-up will be puling a total of 20 amps and will most likely pop the circuit breaker. Best to establish its own circuit or up the circuit breaker providing the wire gauge is sufficient.

As to your other question, yes you can assume other circuits will draw close to their max amperage at start-up and then less once the circuit reaches steady state.

 

[Sky Soldier]

So there are lots of threads about this but I have a question that I don't think anyone has asked. I have an Add-A-Circut and understand the load and the breaker side. All that is fine.

Here is my question:
If I use any 10amp circuit and I add a circut to it, if both circuits use 10amps at the same time, won't that overload the vehicle wiring?

An example: If the headlight circut uses 10amps and I piggyback on it for 10 amps for this socket, won't that possibly draw 20 amps when I turn the headlights on and wouldn't that be a bad thing?

If this is the case, how could you ever add a circut? Don't we have to assume that all circuts could draw the maximum amount?

Oh and the proper (safe) way to add a new circuit would to establish one if there is an empty location on the current fuse panel.....or buy a small marine fuse block and pull a 12 V primary wire to it and then add your circuits.

 

[markthegrea]

But I want a switched one (off when keyoff). How do I do that?

I spent the weekend trying to figure this out. It seemed that even the window switch fuses are hot (the windows would not go up or down though) when the key is off. I can't figure it out!

The only fuse that had no power with key off was the cig lighter.

 

[SteveH]

Maybe use the cig lighter power to power a relay coil to run your new circuit. Supply the circuit power to the new 12v outlet from the battery, and run an in-line fuse near the battery.