Yes, that's essentially how it works, once you press the 'power' button, it will detect voltage across the clamps and starts the timer, if the battery is so flat that it isn't detected, then press and hold the 'override' button to latch the power on, this also prevents the timer running - you'll need to manually power off the unit if you used the override. Also, be aware of the amount of time you leave the pack connected to the vehicle - you'll be putting alternator voltage directly across the Lithium battery, they'll tolerate it for a short period but not minutes at a time. A salesman where the Mrs. works borrowed a GB50 from one of the tech's and killed it by leaving it connected for 10-15 mins.

The pack will get warm in normal use, if it gets 'hot' it will shut down.

Full manual here https://manuals.plus/noco/gbx75-2500a-lithium-jump-starter-manual

My NOCO 150, if overkill in capacity, always started the Westminster fine before fitting a second battery in the boot.
Not needed the NOCO since but is there just in case.
No doubt a cheaper model will do the job just as well. Forty years of progress. 1972-2012

I got a Noco GB70 for work and it has never failed to start anything I have ever put it on. Including a box transit van with two 95ah batteries.

JayGee wrote:

Camtec Craig says you should not jump start these cars as there is a real danger of destroying the ECU - better to trickle charge the battery off the car.

My advice was slightly different... If your out in the field with a dead car, connect a jump pack and walk away for 5 mins and let the car battery recover somewhat before you try starting it... DON'T just connect up the leads and start it...

FF's have upwards of 30 ecu's and jump-starting them can at best put an ecu into a distressed state. In earlier cars YES it very much can kill ecu's...

Just to add to the good advice from Pheonix and Craig, it’s definitely a very good idea to buy a unit with a substantially larger capacity than required, especially if it must be stored in an unheated location.
The battery capacity will drop significantly at very low temperatures, so it’s better to store the unit indoors at room temperature in Winter, this willl also prolong its life, but do not charge in the home if possible (due to fire risk), and do not leave unattended whilst charging, especially overnight.
It’s an expensive purchase, so for maximum longevity, follow the “80-20 Rule” regarding max/min charge/discharge. The worst thing you can do is to charge to 100% and store, this will drastically reduce battery lifetime.

I learned the above during extensive research into Ebike batteriy best practise; I have certainly found the range of our 52V 21Ah Li Ebike batteries is perhaps down by as much as 50% in sub-zero conditions. “If it ain’t broke, don’t fix it” -where’s the fun in that?

I use a GREPRO 2000A great bit of kit Around £65

Has a light and can charge other things through USB, Very handy SDV8