I have an 2018 fx4 super crew 3.5 eco boost. I’d like to eliminate the timer that asks me to either cut off the ignition switch or start the engine when I’m sitting with the engine off and switch in the accessory position. What I’m trying to accomplish is to prevent my lighter plugs from losing power after a few minutes.

 

The simplest thing to is to disconnect your lighter socket from the current feed wire and to run a wire from it directly to the battery (via a fuse of course). Just be aware that the batteries in the newer vehicles are tiny and they will run down sooner than the massive batteries used in the pre-computerized vehicles.

 

Professionally, I've done this before, but I added a 1 hour timer relay.

A while ago I added a second battery in my toolbox that I ran in parallel with the battery under the hood using 0 gauge wire. I also cleaned up my wiring two summers ago and used actual fast trip DC circuit breakers and connector blocks. Wasn't a cheap proposition for the good marine quality stuff.

But my need is extreme - I run high powered radio gear in my truck that can potentially kill my alternator or leave me stranded if I "forget" that I'm on the air too long, or if I want to run multiple rigs, and possibly multiple SDRs. I also have a massive inverter to power things like sidewinders to two or three desktop computers out in the field.

For you, I do recommend a 1 hour timer, but NOT necessary, but be careful! It's easy to forget things overnight - trust me.

I also have an onboard battery maintainer and charger. So for those days I come back home from messing around with radios, I plug my truck in to AC and my batteries are topped off in a couple hours. Mind you, I used AGM batteries for this application.

My next truck will have dual high output alternators, and of course dual (or add my 3rd) batteries. Along with stationary elevated idle control....