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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 12-27-2011, 07:26 PM   #1
Cole Mayfield
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Question 3000mah 4S - How long should I fly ?

Hey Everyone,

I have not been posting on the forums for awhile, but I read them often, and have learned a lot...

For Christmas, I got a Handy King (3D/Aerobatic Aircraft) and it runs a 4S pack... I fly pretty well full throttle with most of the Aerobatics I do and was wanting to have an idea of how long I should fly for on a Fully Charged pack... I picked up a Sky Lipo 4S 3000mah Lipo pack...

What would a good Flight Duration be for me? Any Ideas?? I am trying to keep the pack in good condition...

Thanks for Reading

CM

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Old 12-27-2011, 07:33 PM   #2
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Cole that depends entirely on how much power you are taking from the battery. What are your numbers (amps watts?)....

We don't have enough to answer your question without that data.

And - really you should edit your sig and take out your personal data .... The spam bots search for stuff like email addresses.

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Old 12-27-2011, 08:42 PM   #3
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There are too many variable to give a definitive answer. even with the exact same model two different flyers might get different flight times depending on flying style. Best thing is to fly like you normally do, initially for, say, 4 minutes then land and check the battery voltage. Keep increasing flight time until the voltage is about 15v. That should leave about 15% capacity in the battery which is about as low as you want to go on a regular basis.
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Old 12-27-2011, 09:45 PM   #4
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Do you have a charger that measures how many mAh you put in the battery? In that case, there's a neat trick I learned here on Wattflyer and modified a bit that works great:

Make sure you have a full battery. Pick a really short flight time, like 3.5-4 minutes. Bring her down and charge up the battery. Check how many mAh the charger needed to put in to fill the battery to capacity. Let's say the charger put in 1500mAh. That means you still have 1500mAh left, in other words you have 50% left. Next time you fly, increase the flight time by about 25% and try again until you've reached a point where the charger tells you it puts back about 80% (2400mAh) in the pack. That leaves you with a 20% margin, which is optimal for making your batteries last and leaves you enough spare capacity to handle a go-around or two. Keep an eye on the number of mAh you put in the battery for the next several flight in case you need to fine tune your flight time.

Have fun!

Edit: According to the manual, the stock motor (not sure if that's what you have) has the model number KM0374810. If we google that, we find the following data:

Code NoKM0374810Specification / SizeD37.2 x 48.5 mmPackage1 pc/pkgDescription-Max Speed: 13860rpm
-Kv (rpm/V): 770
-Operating Power: 450W
-Operating Voltage: 8.5-18V
-Operating Current: 30A
-Peak Current: 38A (max. 15 sec.)
-Internal Resistance: 34 m ohms
-Diameter: 37.2mm
-Length: 48.5mm
-Weight: 172g
-Shaft Diameter: 5mm
-Mounting Screw: M3 (Front) and M2.5 (Back)
-Distance of Mounting Holes: 25mm (Front), 15.5mm (Back)
See the full page here:

http://www.theworldmodels.com/para/p...id=84&subcat=0

So the maximum continuous current is 30A, which would mean you'd drain 3000mAh in 3/30=0.1hr=6 minutes. No idea what you draw at full throttle (only way to find out is to measure with a wattmeter), but if that is indeed the motor you're running, you should easily get a 5 minute flight out of it as long as the current stays within the recommended limits.

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Old 12-28-2011, 02:37 AM   #5
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Originally Posted by Cole Mayfield View Post
Hey Everyone,

I have not been posting on the forums for awhile, but I read them often, and have learned a lot...

For Christmas, I got a Handy King (3D/Aerobatic Aircraft) and it runs a 4S pack... I fly pretty well full throttle with most of the Aerobatics I do and was wanting to have an idea of how long I should fly for on a Fully Charged pack... I picked up a Sky Lipo 4S 3000mah Lipo pack...

What would a good Flight Duration be for me? Any Ideas?? I am trying to keep the pack in good condition...

Thanks for Reading

CM
As others have indicated, one very good purchase will be one of those wattmeters. A number of places have them, such as Astroflights wattmeter. Some of the imports are 1/2 the cost of the Astro unit.

If you'd like a good all around digital meter for about $60, check out the Sears Craftsman #82369. It can measure the usual volts, resistance, ohms, and it measures amps without breaking into the motor wires. I use mine a lot. http://www.sears.com/craftsman-digit...p-03482369000P

As for how to use a digital multimeter, take a look:
http://www.wattflyer.com/forums/showthread.php?t=52821

And, as the moderator has suggested, get rid of the personal stuff on your byline! I had someone bust into my yahoo email last year, They were sending all sorts of XXXX stuff under my email address to all my friends in the RC club, and also out of the club. Didn't find out about it until Yahoo sent me an email indicating one of my email addresses didn't exist. The hacker had sent it. Yahoo traced the hacker to somewhere half way around the world.

DennyV
Retired and the days are just too short, busier than ever!
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