I have decided to go 48 volt after all the input from here.

[Kornbread]

I don’t get this? Why double it?

Like hrtkd said, it's a round trip. Have to consider both legs.

 

[MichaelK]

Like hrtkd said, it's a round trip. Have to consider both legs.

Doing the math by hand, yes. But, going with a voltage drop calculator, it depends on the specific calculator. The one I use specifically says to input just the one-way distance.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

 

[Kornbread]

Yeah, that's something that confuses me. Why is it some calcs appear to ignore the round trip? Or do they expect you to input the round trip footage?

 

[rhino]

Yeah, that's something that confuses me. Why is it some calcs appear to ignore the round trip? Or do they expect you to input the round trip footage?

Just poor UI. They should explicitly state if you need to enter one way distance or both.

 

[Dzl]

I don’t get this? Why double it?

Yeah, that's something that confuses me. Why is it some calcs appear to ignore the round trip? Or do they expect you to input the round trip footage?

Voltage drop is always based on round trip distance. People often talk/think in one-way, but that is only is only half of the total (assuming its symmetrical).

Some wire drop calculators use one-way distance and silently multiply it for you (which is one of the reasons for the confusion), better designed calculators will use round trip distance and clearly state it, some don't make it clear what they use. But the math is always based on total round trip distance. The difference is just whether the calculator asks for total distance as the input or whether it asks for half the distance and multiplies by two.

 

[SilverState]

I had a 12v system before on a sailboat and I think in that place it wasn't so bad. Distances were relatively short and the system was small. It was also ~15 years ago when 24v was fancy, 36 edge case, and 48 was something that you'd occasionally hear about. But on a terrestrial system of any size that doesn't have any particular reason to be not 48, go with 48. I think you'll be happy!