50 Amp Receptacle to Inverter

avarusbrightfyre wrote:

DrewE wrote:

avarusbrightfyre wrote:

Wouldn't increasing to 24 or 48 volts require more batteries to reach the same capacity? I believe I would need twice number the batteries at 24 volts to get the same number of amp hours as a 12 volt setup. I plan on mounting the inverter right next to the batteries and using big fat cables to minimize heat.

You do need twice as many batteries to have the same charge capacity (measured in Amp-hours). You do not need twice as many batteries to have the same energy storage (measured in watt-hours), and it's energy that you're ultimately using. Since the voltage to the inverter is greater, the current it requires for the same output is proportionally lower, and so your amp-hour requirements--but not your watt-hour requirements--are also correspondingly lower.

Incidentally, this is basically the same reason why power company distribution lines operate at high voltages: they need to carry much lower currents to supply the same amount of power, and so they can use reasonably sized wires and still have acceptably low line losses.

What about the DC side of the trailer? I would need to step it back down to 12 volts on that side, and wouldn't that bring the capacity back down to what it would have been in a 12v system?

When step down from 24V to 12V, you will get roughly 2x the current out at 12V than goes in at 24V (minus any efficiency losses). Capacity is not lost, just reshaped when using a higher voltage for your storage.

So 100AH at 24V would yield 200AH at 12V.