The 2001 Ranger wiring diagram shows the Lighter or Power Point plug to be fused and Hot all the time, so not on the key switch.
This means it should have 12v all the time.
The Mighty Jump, and other similar products are NOT for "jump starting" an engine, they, and the wiring in your vehicle, do not have and can not carry enough amps for that.
What they are for is to trickle charge a battery that has been drained by leaving a light on or similar "oops" issue.
You plug it into the cigarette lighter socket and then wait for 10 to 15min., the longer the better, unplug it and THEN try starting engine.
DO NOT turn on the key with this type of device connected.
Before using I would test it's voltage, some have reported as much as 30vDC which could fry some electronics in a vehicle, it can be as high as 15vDC but I would be concerned if it was higher.
If car battery is bad or the cars charging system was the reason for the dead battery then Might Jump won't help, simply not enough amps to replace car battery.
So for the specific "oops I left the lights on" this could be helpful.
And yes, after engine is started and charging system is working you can plug the Mighty Jump back in to cigarette lighter socket to be recharged.
Most newer vehicles have "battery savers" that will cut power after 20 minutes or so to prevent the dead battery issues with leaving something on.
Last edited by RonD; 01-21-2014 at 09:41 AM.