electrical question

benburnett

Senior Member
Joined
Oct 5, 2006
Messages
771
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.
 
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.
 
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.:)
 
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