can a capacitor(s) crank a car?

[Solid Shadow]

I've seen a few YouTube vids about using capacitors (specifically ultra, and super caps) to crank a car. I'm skepticall but hopeful of the validity of this feat. (Who am I kidding, it's an excuse to play!)

My first problem is: Can this be accomplished or are these vids bs?

Second, I've come across a few old Mallory 8300 mF 100VDC caps (s# CG832U100G1), but I can NOT find a datasheet anywhere for them. Can I do with these caps that I've seen in the vids, or am I attempting to create a big firecracker? :-?

 

[dick_freebird]

You need 12V to drop to no less than maybe 8V over the course of
the crank-to-fire interval. So call dV=4V. dt is maybe 5 sec if the
motor is not warmed up. Now the amperes, that is a big question.
Let's say 200A cranking load.

So C=I/(dV/t)=200*4/5 = 160 Farad.

Your Mallory caps are not likely mF (millifarad) but uF (microfarad)
and you'd need a few crates of those puppies to make 160 whole
farads worth of "battery".

Supercapacitors do approach this range, and could work better
for a smaller, lower cranking load engine that catches quick. The
higher C supercaps are pretty low voltage, naturally, but there is
a range available (though the high voltage, high C, high reliability
models, you won't like for price one bit - lead acid battery will win
on economics, if not weight and filth.

 

[IanP]

You can buy 150F @ 14V capacitor (build of 6 x 900F cells).
Theoretically it should work, but I’d really like to see them in action ..
:wink:
IanP

 

[Analog Ground]

Supercapacitors are being used to replace batteries in trucks. See below or search:

https://www.truckinginfo.com/blog/o...a-better-electric-mousetrap.aspx?prestitial=1

 

[Solid Shadow]

Thanks guys, much appreciated.