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Old Dec 18, 2009, 12:45 PM
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Golfnutttt's Avatar
United States, ID, Boise
Joined Oct 2009
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Pros. Need Lipo advice.

Can someone reccomend a lipo for a dual rotor heli running 2 370 high power brushed motors? The battery it came with was a 7.4v, 1500 mah lipo. I replaced it with a 7.2v, 2200 mah lipo and it doesnt give me the lift I need. I use a 3CH pcb, that I dont have the specs for, and also wanted to know if someone has a general idea of the requirements for this kind of set up. I'd like to upgrade the battery and have no idea what to get. I've researched and not sure about burst rate, the voltage limits or requirements or how high I can go on mah rating without sacraficing power. My heli is an import so specs are limited. It's 2' 4" long, 12" in height and the blades measure 9 1/2" a piece. Any help is appreciated. Thanks in advance.
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Old Dec 18, 2009, 01:17 PM
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Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
4,323 Posts
The problem is that you significantly increased the weight of the battery when you went over to the 2200mah.

If you're trying to get "more lift" then what you actually need to be looking for is a battery with a higher C rating than the one that came with the chopper. The C rating is the amount of current the battery can put out.

In order to figure out the amperage (current) the battery can put out you use this formula:

Current * mah divided by 1000 = Amperage. So a 15c 1500mah lipo would put out 22.5 amps. 15 * (1500/1000) = 15 * 1.5 = 22.5. Of course you haven't told us the C rating of your original battery.

The formula to figure flight times in minutes is:

MAH of battery divided by 1000 divided by average amperage draw of motors * 60. This gives us the amps per hour of the battery (mah divided by 1000) then it divides that by the amperage drawn and then multiply by 60 to turn hours into minutes.

You can figure out the average amperage draw of your motors by reversing the formula.

If you got 10 minute flights on the 2200mah lipo then:

10 / 60 = 0.16666666666666666666666666666667
2200 / 0.16666666666666666666666666666667 * .001 = 13.200000000000000000000000000053

So your motors in this example would be drawing a little over 13.2 amps average combined.

Pretty sure my math is right here, but I have been known to make mistakes. I hope this clarifies things for you?
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Last edited by Barak1001; Dec 18, 2009 at 01:30 PM. Reason: Making it easier to read.
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