Belt / floor stops at 13klm, have to get off, turn power off and restart then only lasts for several minutes before stopping again

Yes.

On some low power charging systems it is possible a weak battery can start/run the engine and even mow for a several minutes and then the mower deck cuts out, you turn the deck back on and it last for a few more minutes and deck stops again. Eventually it will no longer engage.

A fully charged battery will read >12.5 VDC with engine off.

The tricky part is figuring out if the battery is really bad or merely undercharged because of a failing charging system.

check adjust belt tension
may have to clean under belt area as there could be a build up that is stopping the free movement of the belt as it gets hot

Check oil level may be low

Some treadmills seize themselves (burnout) because their floor belt works (runs) dry to the point where the motor has to strain in rotating the floor belt, into it gets hotter and burns out or it may burn out the electronics that control its speed. One of the problem in relation to this kind of burn out is the lack of floor belt lubrication. So, when was the last time you ever lubricated the floor belt with the appropriate lubricant, such as silicone spray? I have an electric treadmill of 9 years and it still runs like new. Why? Because before I use it to walk, jog or run, I apply a couple of evenly sprayed squirts under the floor belt where it makes contact with the smooth steel base. Lightly spraying on the base up and down and evenly from side to side, just a couple of seconds of short sprays to lubricate the floor belt base (do not over spray or you'll have lubricant everywhere on the floor/carpet. You can spray it on a lint-less cloth outside the house then go back to the treadmill, lift the floor belt with your fingers and smear the moisturised cloth evenly on the base) and then give it a little power to make the belt slowly rotate so that the overall belt is lubricated, run it for half a minute before beginning to exercise on it. This should make the belt run smooth for a month without straining the motor, depending on how often it is used. I use it one hour each day, 4 days per week besides other gym training.

Sounds to me like your belt may be slipping on the front of your engine. If it is in fact the belt, (not being particularly familiar with Jeep) be careful if you do try and make it to your mechanic. Have some one follow you if possible and or carry a cell phone incase you need help enroute. It is most likely a serpantine belt and if it does brake you may loose power steering, battery charging power (alternator) and worse, cooling ability. (AC also if you have it) I would call your mechanic(s) for their advice. A serpentine belt is not that hard to replace if you or some one is know is mechanically inclined.

A treadmill will shut down from to much friction which is due to high motor current because the walkbelt and deck are not properly lubricated. I would recommend replacing the motor controller,walkbelt,deck and applying .5 oz of lubricant on the deck every 3-6 months or 100 hours of use. This will extend your treadmill's life many years.

Just take off your carb and give it a good cleaning. Be careful and watch how everything comes apart so you can put it back together with little or no trouble.

The motor for the machine is probably burned out with the power off you can check the motor winding with a meter ohm the wire out to the motor if no resistance bad motor.

This sure sounds like a bad transmission. Turn the transmission by hand to feel and listen to it. It should be smooth and quiet.

Check the timing, if it is way off the belt has jumped and the cam is out of time, also are there any burn marks on the insulators of the spark plug wires that go down into the head?? that is a common problem, If the car is a hig miler then replace the wires with a high quality set, don't use cheapo wire sets.One other thing make sure the rubber intake hose is properly connect to the MAF sensor and intake throttle body and has no cracks or leaks