SHSTEADFASTTHE PRACTICAL HOME GUIDE

Electrical power/ CALCULATOR

Inverter running and motor-start screen

Compare one documented motor start plus other loads with derated continuous and surge inverter ratings.

Exclude the motor entered below.
Use documented or measured real running power.
Use total starting watts or a manufacturer-supported equivalent, not an assumed universal multiplier.
Use the applicable output rating at the intended temperature, voltage and power factor.
The rating must last at least as long as the documented motor start.
Allowance for operating condition and design margin; follow manufacturer limits.
Combined running requirement

1,300 W

Combined starting requirement

2,500 W

Allowed continuous output

2,700 W

Allowed surge output

5,400 W

Continuous-power margin

1,400 W

Starting-power margin

2,900 W

Interpretation:The simplified screen leaves 1,400 W of continuous margin and 2,900 W of starting margin. Confirm start duration, VA and battery-side limits.

One motor starts while all entered other loads remain steady. Watts are compared directly. The screen excludes VA, power factor, waveform compatibility, start duration, voltage dip, multiple starts, battery current limits, cable loss, inverter temperature and protection behaviour. The inverter and motor manufacturers must confirm compatibility.

Continue your calculation

Electrical power

DC cable voltage drop

Estimate copper-cable voltage drop, percentage loss and heat at a steady current.

Electrical power

Inverter DC input current

Convert an AC load and inverter efficiency into approximate battery-side power and current.

Electrical power

Battery runtime from a steady load

Estimate ideal runtime from nominal energy, usable fraction, inverter efficiency and load.

Electrical power

DC cable area for a voltage-drop target

Estimate the copper conductor area needed to keep steady DC voltage drop below a chosen percentage.