What does second wire (with 4 amp fuse) off of battery go to?

[NewbieBoatGuy]

I have a Malibu Echelon 94 boat.  There's a second red wire off of the battery with a 4 amp in line fuse a few inches off the terminal.  The fuse blows every time I turn the ignition key.  I'd thought it went to the radio- as that wasn't working, but after replacing the small radio 10 amp mini fuse, the radio works now even with this other fuse blown, I'm curious what's it's purpose?  Anybody know? 

[justgary]

Automatic bilge pump, perhaps?

[cowwboy]

Or a battery charger? 

[NewbieBoatGuy]

excuse my ignorance, here.  Is the automatic bilge pump different than the toggle switch for the bilge pump?  The bilge pump does work when I click the switch.

[NewbieBoatGuy]

what would a "battery charger" do?  Charge the boat battery? or have another port somewhere to charge other devices?

[justgary]

5 hours ago, NewbieBoatGuy said:

excuse my ignorance, here.  Is the automatic bilge pump different than the toggle switch for the bilge pump?  The bilge pump does work when I click the switch.

Your bilge pump should have a float switch that always has power available.  It should have a fuse somewhere.

[justgary]

5 hours ago, NewbieBoatGuy said:

what would a "battery charger" do?  Charge the boat battery? or have another port somewhere to charge other devices?

Charge the boat battery.

[electricjohn]

Try following the wire.