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Old 12-23-2010, 05:25 AM   #1
Bluefronted
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Default Help - understanding Watt meter

Hi Guys,

I received my Turnighy wattmeter yesterday. I tested it and would like to know which reading will tell me how many amps(I) is drawn from the pack in a minute.

It has:

A - amps currently drawn
Ap- peak amps drawn
w- watts being drawn currently
Wp- peak watts drawn
V
vp
ah-amp hours


Thanks
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Old 12-23-2010, 05:43 AM   #2
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I'm not sure I understand from your question what it is you want to measure. Amp-Hr is a measure of battery capacity consumed. If you have an 1800 mAh and you drain 0.9 Ah from it you've used 1/2 of its capacity, regardless of how long you took to do that.

Mathematically Ah is the time integral of the current draw. If the current is constant then Ah is just the product of current in amps times the time in hours. So 1.8 amps for an hour is 1.8 Ah or 1800 mAh. The same amount of energy can be used by drawing 3.6 amps for 30 minutes (1/2 hour).
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Old 12-23-2010, 05:43 AM   #3
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You will have to time it for one minute, but it's ah- amp hours.

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Old 12-23-2010, 06:00 AM   #4
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Thanks,

Ok , i will need to work with the amp hours , as I want to calculate how long will my 2.2a last per flight
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Old 12-23-2010, 09:17 AM   #5
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Originally Posted by Bluefronted View Post
Thanks,

Ok , i will need to work with the amp hours , as I want to calculate how long will my 2.2a last per flight
That all depends on if your going to be flying the plane at 1/2 3/4 or WOT all the time, so it will depend on what throttle setting you will be using, by using throttle management, you can extend the amount of flight time on your lipo, so its a given, if your going to be flying WOT all the time, then that will only give you that estimate for WOT, not for a throttle managed flight, hope that helps, Chellie

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Old 12-23-2010, 12:17 PM   #6
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An example for WOT throughout the flight (as Chellie says, you may well only average half throttle): You have a 2200mAh pack.... you should reckon on being able to extract about 80% of that before you hit LVC... so now we work on 1760mAh.

Let's say you are drawing 20A at WOT... your flight time (at continuous WOT) will be:

1760/20000 x 60 = 5.28 minutes
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