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24V amps

Voltage

Load power

Power factor

Current 10 A

240 W ÷ 24 V

Fuse at 125% 12.5 A

In milliamps 10,000 mA

Equivalent resistance 2.4 Ω

A = W ÷ 24 · half the current of 12 V

At 24 volts, amps are watts divided by twenty-four. A 240 W load draws 10 A — exactly half what the same load would draw at 12 V, which is the whole reason larger off-grid systems use 24 or 48 volts.

How to work out 24 V current

1 Enter the load in watts.

2 Read the current and the fuse figure.

3 Compare against the same load at 12 V — it will be double.

4 Size cable for the current over the full round-trip length.

Doubling the system voltage halves the current, which quarters the resistive loss in the cable, because loss goes with the square of current. That is the single strongest argument for 24 V over 12 V in anything but the smallest installation. The counterweight is component availability: 12 V accessories are everywhere and 24 V ones are a specialist purchase, so many systems end up with a 24 V bank and a DC-DC converter feeding a 12 V branch for the accessories.

Questions

How many amps is 240 watts at 24 volts? −

10 A. The same 240 W at 12 V would be 20 A.

Why choose 24 V over 12 V? +

Can I run 12 V accessories from a 24 V bank? +

Do I still need heavy cable at 24 V? +

Is 48 V better still? +

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