if I can run everything for 10 seconds that's more than enough for a test.
And now, some real fizix - EC=IT
If a capacitor is discharged with a constant current load, this very simple equation tells you how long the cap can run things.
If your cap is charged up to 12 V, and the device you are powering must have at least 10 V to function, then E = 2 V, the amount of output voltage change you can tolerate.
If your device draws three amps, the I = 3
Your cap is 2 F, so C = 2
Rearranging the equation, T = (E x C) / I = (2 x 2) / 3 = 1.33 seconds.
A lower operating current extends the running time; with a 1 A load the run time is 4 seconds.
ak