Why not try turning a 3-wire mini volt meter https://www.adafruit.com/products/705 into a proper probe?
Even @ 50 milliseconds the last digit reacts though clearly not at that rate. Might even be handy as a way to measure voltage droop.
I bought this to put in my wheezy old truck, but until then its handy on my small workspace as I don't have meter probe wires knocking stuff around.
Hint: the negative wire should be the longer one. Or you can burn the tip of your finger and give up on that like me.