Inverter

Is your truck running while it's on?
On mine the display is in reference to the state of charge on my batteries.

 

If the coffee maker has a bunch of electronics in it, it may require the use of a pure sine wave inverter to operate properly. A simple on/off type coffee maker should work fine.
If the appliance draws 750 watts while brewing, the inverter will pull about 75 amps from the batteries. If you had it set to fire up with the truck off, it would have caused a low voltage condition and shut itself off. When you fire up the truck it will work fine. Unless it needs the pure sine wave type inverter.

 

There are a couple things here.

First off this is an inductive load, a little different than normal loads.

Second the five cup I have sitting here (mainstays) is 1200 watts, not 750.

Third there is overhead for every inverter so if you are using 1200 watts, may a couple hundred is being lost in heat and running the thing. The fan will run for a bit to lower the temps on the switching transistors.

Fourth that one is a chinese made modified sinewave inverter which more often than not isn't too great for coffee makers.

Fifth and finally, I hope you have it wired in right and it is fused.

 

Yeah the first time i was going to get an inverter and had to figure out how big I was very surprised to find out how many watts these little pots use.

 

I have The same pot as him , it says right on the bottom 700w manstays ( walmart) 5cup. Been using them for bout 5 years.
Before that Mr. Coffee those are 650w.
Up until last February I've ran them on Chinese modified sine with no problem.
The Mr. Coffee I used to run that off a 1000w.

 

I heat water in the mike and use a french press. Way better cup of coffee. Takes about 10 minutes from start to finish. About the same time as a pretrip while I'm getting dressed and circling the truck. 16 0z water at 6 mins in the 50$ mike. 4 scoops of MH colombian in the carafe. Zoom baby!!!

 

One of the companies I worked for had those 1500W cobras in their trucks, but they sucked. As I had to start the engine every time I had to use my microwave. Otherwise, I couldn't use it.

The 1800W cobras work far better, relative to the 1500W models, at least for me.