Fuse and wire size

[Tractor Seabee]

It doesn't work that way. The voltage is constant at whatever the charging system is putting out (ideally between 13.8 and 14.2 volts) so increasing the total resistance in the circuit lowers the amperage draw.

Mace,

You may want to review this some more. Yes, at the battery it will be whatever the Voltage Regulator is set for. 50 feet from the battery; wire size staying the same, you will have less than that voltage, but the lights, winch motor Etc will still try to put out its rated wattage therefore raising the amps till the fuse blows or the wire melts. Thats why the fuse is rated per the wire size; to keep the wire from melting. Set this up on the bench and it will become clear. Note I man deliberately avoiding gett into theory too deep.

Ron

 

[arlen4720]

Mace,

You may want to review this some more. Yes, at the battery it will be whatever the Voltage Regulator is set for. 50 feet from the battery; wire size staying the same, you will have less than that voltage, but the lights, winch motor Etc will still try to put out its rated wattage therefore raising the amps till the fuse blows or the wire melts. Thats why the fuse is rated per the wire size; to keep the wire from melting. Set this up on the bench and it will become clear. Note I man deliberately avoiding gett into theory too deep.

Ron

This is incorrect. Resistive loads such as lights and heaters will draw less amps as the voltage drops. The wattage is not fixed. The only thing fixed in the circuit is the resistance.
Remember E=IR, or solving for I...
I=E/R
R being fixed, its easy to see that as voltage drops current drops too (and wattage).
I would challenge you to set up a light bulb and 2, 6 volt batteries on the bench.
I will bet you next weeks paycheck that the circuit will draw less amps at 6 volts than at 12 volts.

 

[DT86]

You guys are making my brain hurt.

 

[Fallon]

You guys are making my brain hurt.

Just stick well under the ratings and you will be fine 4 lights on a 15 amp circuit will get the job done just fine.

 

[arlen4720]

Just stick well under the ratings and you will be fine 4 lights on a 15 amp circuit will get the job done just fine.

Finally some usable advice

 

[Fallon]

I'm also running my 4 LEDs off a switch just fine. No relay. The wire really couldn't be any shorter it goes straight from the battery to the fuse block. A couple inches to the switch then straight along the frame yo the lights.

 

[Mace Canute]

Mace,

You may want to review this some more. Yes, at the battery it will be whatever the Voltage Regulator is set for. 50 feet from the battery; wire size staying the same, you will have less than that voltage, but the lights, winch motor Etc will still try to put out its rated wattage therefore raising the amps till the fuse blows or the wire melts. Thats why the fuse is rated per the wire size; to keep the wire from melting. Set this up on the bench and it will become clear. Note I man deliberately avoiding gett into theory too deep.

Ron

I think you should do a little more reviewing about the difference between constant impedance loads (such as lights and resistive heaters) and constant power loads (such as electric motors and regulated power supplies).

 

[Scrambler82]

Wow, R we beating this one to death !

The idea of using a relay is to keep the higher current flow outside of the cab or from under the dash panel, in turn reducing any chance of causing a fire.

I know you guys are up on all of the LED Lighting and the need or not for a relay but if your happy running 10 amps thru a switch, no matter what the rating of the switch is... Good luck.

Here is a schematics I have passed around, luck to Ya no matter how you do it !