Voltage gauge readings question

I replaced the stock headlights with LEDs. I then snipped off the plug for the one of the original parking lights and wired in a cheap gauge off of Ebay that reads volts.

My question is, is it normal for voltage to jump from 13.5 to 14.4 to 13.8 to 14.2 and so on, changing every couple of seconds? Very rarely will it read a constant voltage for any length of time, though it's always in the 13 to 14 volt range.

Just wondering if I should try a different gauge or if this is normal.

Thanks.

Mmmm...@DEcosse will weigh I'm sure but here is my 2 cents worth.
The battery is a rather large capacitor, which should smooth out any sudden voltage changes. To me that indicates a bad connection or bad voltage indicator.