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Old Feb 06, 2006, 05:59 PM
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Joined Jan 2006
20 Posts
measure wattage draw at home w/ voltmeter?

If I've got a ready-to-fly plane with power system installed, is there a way to measure the actual wattage draw while on the ground? I'm pretty sure the answer to this question is "yes" but I'm not sure exactly how to do it.

I've heard of the whattmeter but don't have one... I'm mostly literate with using a standard voltmeter... is measuring the power draw as simple as hooking up the battery and measuring the voltage drop and amp draw across the two battery terminals?

Maybe asked another way is "if all I have is a flight-ready airplane and a voltmeter, how do I make this happen?"
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Old Feb 06, 2006, 06:01 PM
-plancks only-
Franck's Avatar
The Netherlands, UT, Benschop
Joined Oct 2001
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Old Feb 06, 2006, 06:23 PM
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Staffs, UK
Joined Nov 2003
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To measure watts you need to measure current AND voltage at the same time. This takes either a wattmeter or TWO voltmeters.

But I guess you really want to measure the current draw in which case the shunt and a voltmeter that reads down to millivolts will do it.

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Old Feb 06, 2006, 08:44 PM
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Joined Oct 2005
659 Posts
here's my "watt meter"...the ammeter is 1A full scale but with a shunt
it can measure either 10 A max (shunt is 14 inches of 18awg copper
wire) or 20 A max (shunt of 28 inches of 18awg copper wire) - see
pic of backside. I've used the multimeter to verify the new scales. The
voltmeter is 0-15 V. Don't forget the fuse !

Total cost: about 25 bucks if you buy all you see in the picks.

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