Thread: Watt Meters
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Old 04-20-2014, 01:37 AM   #2
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Originally Posted by garyp1029 View Post
It seems to be the general consensus that a watt meter is almost required equipment in this hobby. I am almost convinced, but WHICH one? The AstroFlight WhattMeter gets high marks as does the Watt's Up. However, the GT is about half the price of those two. Anyone got a good reason for not opting for the GT? Obviously the greatest possible accuracy is desirable, but in considering watt meters what constitutes "close enough for all practical purposes"? I see that HobbyKing also offers its own brand. Any other meters that one should consider? Thanks. Gary
I've got an Astro wattmeter, and have checked it against my $350 Fluke 87V 0.2% accuracy digital meter. That Astro meter is accurate to a percent or two. This is far more accuracy than is required for our electric models.

The actual current pulled by your motor while in flight can vary by 50% more more, depending if you're flying level, climbing, or diving. The important use for a wattmeter, is to verify that you're running your motor/esc/battery pack within their ratings. That would only require perhaps plus/minus 10% accuracy. So, as you indicate, just about any quality wattmeter will be "good enough".

Just be certain the wattmeter you buy will be capable of measuring the currents pulled by your models. That won't be a problem, unless you're flying large models that pull over 60-80 Amps or more out of your battery. If you're running over 60 amps or so, check out the Sears Craftsman #82369 ($55)digital clamp on AC AND DC voltmeter/ammeter. This meter has two DC current ranges, 0-40 Amps, and 0-400 Amps. That will cover just about everything, including the starter on the diesel engine of your truck. It's easy to use, just clamp its jaws around ONE of the battery lead conductors, and read current directly. (Note that most digital clamp on meters are AC only, not usable for our stuff.

One of my club members bought the Hobby King wattmeter, and found it was way the heck off, like 50%. Hobby King replaced it, and the replacement unit works just fine.

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