You're probably ok. I can't find anything conclusive one way or the other, just random anecdotes.

It's probably more of a belt-and-suspenders thing. In a perfect universe, when you jump-start somebody's car, they're just borrowing you battery for a second - it wouldn't matter if your car was off or not. But in the real world, the car being jumped might have shorts, a damaged battery, or other goofy electrical issues that could damage your battery or alternator system (no good deed...) - having everything off would help prevent that.

For many years, I've carried a rechargeable backup battery jump-starter doodad in my trunk, both for my own use and to help others without having to hook up my car to anybody else's. (In fact. it's old enough I should probably replace it...)

 

some pretty cool lithium-ion battery pack chargers on the market recently!
Charge everyones phones while jump starting the car!! lol

 

That makes a lot of sense. I was worried cause of all the electronics in the Technology Package but since you explained everything I can now rest peacefully knowing that my car is fine. Next time I give a jump I’ll be sure to leave my car off. It’s just the heat of the moment that you forget the critical things. Luckily for me her car was a newer model VW Jetta and her battery was original. Thanks for the swift replies everyone!

 

Personally, I would never jump start someone else's car if my engine were NOT running.

 

 

If you have your car running, and especially if you keep the engine revved up (not too high but maybe three grand), the load is not nearly as much of a shock to the electrical system because the alternator is spinning fast enough to supply the energy needed.

 

 

 

Over my driving life of 45+ years I've probably jump started 100 cars; I've literally ALWAYS connected the jumper cables with the engine running. Not that I've ever checked, but I don't believe I've seen a directive to do otherwise.

 

 

 

I actually have two $1,100.00 lithium ion batteries in my Ferrari in addition to a standard lead acid battery. They are used primarily for my monster 3000 Watt sound system, but if I go out of town on business for a few weeks, I'll flip a toggle switch to engage the two LiOn batteries before I hit the ignition and the car fires right up with authority. In a sense, this is like jump starting the car.

 

I have a battery tender that costs less


awesome ride though

 

 

Hmmm, a 3,000 Watt aftermarket sound system seems more than a bit redundant; to my ear at least, the symphony emanating from the engine bay is way more pleasing than an aftermarket sound system of any power.

 

I had a 2007 Kinetic Blue Pearl TL Type-S for many years. One time when I had it in the shop for a service, they gave me a SH-AWD as a loaner for two days. I fell in love with the car. I really didn't like the looks but it was a total drivers car. So when the Type-S odometer passed 180K miles, it was time to replace it with something, and by that time, the look of the SH-AWD had grown on me, especially after seeing pictures on this site with the horrid grills painted the body color.

 

I own a high end car audio company that caters to Ferraris only, so of course I must have the most monster car audio system in my car for shows, demos, etc.
At my age, I prefer to listen to only one 8" subwoofer. At a show, I wear hearing protection and fire all ten 8" subs. The ground literally shakes.