Piggyback fuse or relay

[jeeeep]

Installed the Dometic wiring harness which includes a standard 12v plug and 12v screw in plug, it's now up and out of the available storage space which I didn't like about the stock plug.

What I do like about the stock plug is the fuse can be moved to become ignition switch powered which is what I use when traveling with a cooler.
I plug a portable power battery into the 12v plug which charges while driving then shuts off and the portable battery keeps the cooler going without it draining the starting battery.

Now that I've wired the Dometic direct to battery, I'd like to wire it to be ignition switched and can't decide if the easy way (piggyback fuse) would be as good as a relay switch.

The Dometic wiring has a 15a fuse, the stock 12v outlet uses a 20a fuse but I'm thinking even if I didn't use the stock 12v plug it would still be limited to the 160w max rating where if I use a relay I could safely plug in a 300w inverter to maximize the portable battery charge during shorter drive times.

 

[Mike Pierson]

Clean install, I like! I’d think the relay would be safer but also more functional down the road if you wanted to add more devices. You could add a fuse block back there and have solid power from the battery.

 

[jeeeep]

Clean install, I like! I’d think the relay would be safer but also more functional down the road if you wanted to add more devices. You could add a fuse block back there and have solid power from the battery.

thanks, I found an existing hole in the corner that allowed me to pass the wiring thru the foam plug. It was tight and would've been a lot easier had I removed the paneling but I enjoy making it difficult and cussing a lot, LOL.

That makes sense with the relay and fuse block, I left room to mount some additional items. I'm thinking I can use a piggyback fuse on the OEM 12v to power when the ignition is on, connect it to a relay with the cooler/portable battery wiring and have zero affect on the stock fuse box.

I left enough wire thinking I might put a switch but reading more wiring books, even that idea would be better with a relay.

It's in my head, but will simmer there for a bit until I'm confident I know what I'm doing

 

[Mike Pierson]

thanks, I found an existing hole in the corner that allowed me to pass the wiring thru the foam plug. It was tight and would've been a lot easier had I removed the paneling but I enjoy making it difficult and cussing a lot, LOL.

That makes sense with the relay and fuse block, I left room to mount some additional items. I'm thinking I can use a piggyback fuse on the OEM 12v to power when the ignition is on, connect it to a relay with the cooler/portable battery wiring and have zero affect on the stock fuse box.

I left enough wire thinking I might put a switch but reading more wiring books, even that idea would be better with a relay.

It's in my head, but will simmer there for a bit until I'm confident I know what I'm doing

Sounds like a good plan to me. Keep this updated if you don’t mind, I’d like to do something like this too. Of course, once you have yours all dialed in perfectly. Lol

 

[black pearl]

I personally would run through a relay.

that’s a good looking install!

 

[Andy5160]

Installed the Dometic wiring harness which includes a standard 12v plug and 12v screw in plug, it's now up and out of the available storage space which I didn't like about the stock plug.

What I do like about the stock plug is the fuse can be moved to become ignition switch powered which is what I use when traveling with a cooler.
I plug a portable power battery into the 12v plug which charges while driving then shuts off and the portable battery keeps the cooler going without it draining the starting battery.

Now that I've wired the Dometic direct to battery, I'd like to wire it to be ignition switched and can't decide if the easy way (piggyback fuse) would be as good as a relay switch.

The Dometic wiring has a 15a fuse, the stock 12v outlet uses a 20a fuse but I'm thinking even if I didn't use the stock 12v plug it would still be limited to the 160w max rating where if I use a relay I could safely plug in a 300w inverter to maximize the portable battery charge during shorter drive times.

View attachment 376993

Nice set up!!

 

[Billy Joe]

Relay, if it were me. Nice install, very clean.