out with jumper cables, in with jump boxes

[rphillips]

Well, a lot of the insulation has cracked & is falling off my 40 yr. old Jumper cables soooo, My first shot at a "Jump Box". I just bought a Noco GB70, 2000A. Hard to imagine they don't come with an instruction book. So Looking on computer I've not found my answer... It says for fast charging using the included 12V wire with 12V cigarette lighter plug on one end and little 2 prong plug on the other and plug it up to your auto. It says it should charge in about 2.5 hrs. It doesn't mention it, but should the eng. be running, off, or does it matter? With the eng. not running could this thing take too much charge out of my auto battery that my auto may not start? Will this box charge faster, less than 2.5 hrs., if the eng. is left running?