8 Gauge Wire
Got 25' of red and black 8 gauge copper wire, a 40 amp breaker and some lugs. I plan on wiring this truck correctly for the 12v frig. I hate to admit I never wired the three previous trucks correctl...
Forum Discussion
Depending on the calculator or table you use, distance is measured as one-way (as a crow flies) or two-way (round trip). If your battery and alternator are 25' apart, that would be 25' one-way or 50' two-way (25' POS + 25' NEG). The ever popular BlueSea voltage drop table is TWO-WAY based.
As for voltage drop, the 3% and 10% rules apply to most device types, but not necessarily to DC-to-DC converters which are designed boost voltage, aka counter voltage drop.
Sterling has a video where they compare straight alternator-to-battery wiring where the wire has to be "huge" to counter voltage drop, but then with a DC-to-DC converter, the wire can be much smaller and cheaper and still get the job done. For the alternator to DC-to-DC wire, see the manufacturers length to AWG recommendations rather than needlessly oversizing/overspending on AWG based on a 3% or 10% voltage drop rule. At least for Sterling, they support down to 11.0VDC, or roughly a 23% voltage drop off at 14.4VDC alternator. To counter voltage drop on the output side, the DC-to-DC will have to pull a few more amps, and Sterling specs the 60A output could require up to 80A of input from the alternator. I don't recommend pushing the 20%+ limit however.
As for voltage drop, the 3% and 10% rules apply to most device types, but not necessarily to DC-to-DC converters which are designed boost voltage, aka counter voltage drop.
Sterling has a video where they compare straight alternator-to-battery wiring where the wire has to be "huge" to counter voltage drop, but then with a DC-to-DC converter, the wire can be much smaller and cheaper and still get the job done. For the alternator to DC-to-DC wire, see the manufacturers length to AWG recommendations rather than needlessly oversizing/overspending on AWG based on a 3% or 10% voltage drop rule. At least for Sterling, they support down to 11.0VDC, or roughly a 23% voltage drop off at 14.4VDC alternator. To counter voltage drop on the output side, the DC-to-DC will have to pull a few more amps, and Sterling specs the 60A output could require up to 80A of input from the alternator. I don't recommend pushing the 20%+ limit however.
