I have one of these, and can say from experience, I have started a H1 diesel (dual battery system) a few times; and one day, for over an hour, cranked the engine numerous times to troubleshoot a fuel problem. I have also used it when working on my popup when I adjusted the limits switches for the power winch. Lifted and lowered the roof at least a half dozen time. (Too lazy to pull the batteries out of the garage an connect.)
Only frill is the charge port (accessory plug) can be used to power a small Cobra converter if needed.
You can charge it via the accessory plug from a running vehicle. I comes with a cord with two male plugs; this is a time charge and you must disconnect manually to keep from overcharging the battery. Or you can just plug a female end of an extension cord into the charge port; this is automatic and can be left plugged in at all times since it will cut charging automatically.
Amazon.com: Jump-N-Carry JNC660 1700 Peak Amp 12-Volt Jump Starter: Automotive