Volt gauge jumping up and down

[EricT22]

Not sure if this is the right place to post this but ill start here and mods can move if needed.

Voltage keeps jumping from 12v to 15-17v periodically when at low speeds. Basically when I’m traveling in no wake zones i can head the blower change sound so i know its just not the gauge. Installed a new depth/fish finder recently and used it for the first time today. The voltage readout on that was pretty consistent at 14v when the gauge on the boat was reading 12v. Not sure where to start here if i should do anything at all or if its normal. Battery is brand new also. TIA

 

[Bondo]

Not sure if this is the right place to post this but ill start here and mods can move if needed.

Voltage keeps jumping from 12v to 15-17v periodically when at low speeds. Basically when I’m traveling in no wake zones i can head the blower change sound so i know its just not the gauge. Installed a new depth/fish finder recently and used it for the first time today. The voltage readout on that was pretty consistent at 14v when the gauge on the boat was reading 12v. Not sure where to start here if i should do anything at all or if its normal. Battery is brand new also. TIA

Ayuh,..... I'm guessin' this boat has a motor,..??

 

[EricT22]

Ahh lucky guess!!!!! 4.3 Merc

 

[bruceb58]

Its probably normal. If it's a one wire alternator, it's very normal.