Jump start on 4s 16.8v LiPo?

LiPo batteries when fully charged are 4.2v per cell. I've jump started cars a couple time on a 3s (12.6v) which worked ok. The batteries can't keep the voltage at 12.6 so it struggles but does work. My logic here is that with a 4s battery (16.8v) connected to a dead car battery would immediately drop the voltage to something safe even before the starter cranks over.

I'm considering running my battery a little, maybe 11v, disconnecting it from the vehicle, then connecting the 4s LiPo and checking the voltage. Other than damaging the LiPo, do you see any problems with this logic?

before anyone says why, because I have a lot of LiPo batteries.