electrical question

[benburnett]

Posting this in both forums hoping that someone can help me with it.

I have an electrical question for anyone who knows enough to help. I have a customer that has an electrical requirement that we need to meet for him. He needs to run a machine that draws 2.5 amps using 115 Volt.

He has a 400 watt inverter hooked up to a 12 volt battery for the machine.

According to my research, the following are the formulas to figure out the amp draw by the inverter when being used.

Watts = volts x amps 2.5 amps x 115 volts = 287.5 watts

Amp = watts / volts x 1.11 287.5 watts / 12 x 1.11 = 26.5 amp draw per hour.

Can anyone confirm this for me or disprove it for me. Would appreciate any help.

 

[quailsroost]

Ben Nosmo is right on the starting load, if you figure 2 1/2 times running load is your starting load you will be very close and that is a very momentary load, inverters have a peak or max that takes that in to consideration. RMS is the root mean square of a wave length and 26.5 amps per hour is a bit high and to the right for this application.

 

[benburnett]

electrical

The 2.5 is the max amp draw of the unit. Still waiting to hear what the running draw is. Have learned a lot about batteries though over the last few days.