" Ok, Seems senseless to charge an expendable charge in a laptop with another expendable battery. Duh! But just checking."
Millions of people do this everyday, with pocket size USB power banks for their phone or tablet
Quite a few lithium jump boosters have DC output ports with proper adapter for charging notebooks and laptops,
Before it died the one I had could do 12v, 15v, 19v
Had push button to select voltage out,
I damaged it trying to start a suburban with dead battery hidden under floor in the rear, with jumper posts under hood, poor power to the battery, and heavy amps from booster direct to starter when turning the key,
Warning don't connect to jumper posts under the hood, always connect directly to the start battery,
If it's not your car, tell them to remove seat, open trunk bed, etc.. What ever has to be done to access the start battery, with lithium jump booster,
After I tried to help them and failed, the battery in my booster swelled up, it started losing power , power faded away with each use, it was only 2 years old
$80 gone, now I need a new one
Note: the warning is just info about my experience, not related to OP question, maybe it will prevent some one from doing the same thing and killing their jump start booster