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Old Apr 06, 2015, 10:16 PM
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Watt Hours vs C rating

What is the C rating of The Great Planes Lipo 3S 1050mAh 11.1v battery? It says it has 11.7wh. How do you convert watt hours to C rating? Or how many amps does this battery produce? I tried to figure this out but I got confused. I want to run 1350mAh 11.1v 20c lipos in my Heli-Max Axe CP. Last time they ran it for a few times then the receiver board went out. I replace it then the esc, mixer, gyro caught
on fire. Not sure if it was because of to many amps from the lipo. That was in the original Axe Cp upgraded to run a 3s lipo. Now I have the 2.4 GHz meant to run the 1050mAh 11.1v 11.7wh lipo. Are the 1350mAh 11.1v 20c lipos going to fry this one?

Thanks Eric
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Old Apr 06, 2015, 10:28 PM
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A battery will only supply what is asked of it regarding amps. Think of amps as the fuel in a gas tank to a car, the engine will only take as much out as you ask of it (via the gas pedal).

You say you upgraded the original one you had? Sounds like maybe you didn't do it right and a 3S was too much for the electronics you had.
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Old Apr 06, 2015, 10:46 PM
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No information on that pack anywhere. But $30 for a 3s1050mah? That's twice the price of 50C packs from headsuprc.com .
Wh is the power the battery will provide for 1 hour. Multiply pack voltage x battery capacity in Amps.
11.1V x 1.05Ah = 11.655Wh
Tells you nothing about the maximum amps the pack can deliver (C-rate).
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Old Apr 06, 2015, 10:49 PM
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The upgrade was sold by Heli-max and you just hooked it up between the 3s lipo and the mixing board. At the time you were supposed to use a GP 950mAh 11.1v lipo. I used a Flyzone 1300mAh 15c lipo. Batteries never got hot or swelled up. Don't know but going to try again.
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Old Apr 07, 2015, 02:08 AM
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Quote:
Originally Posted by ericlhaase68 View Post
What is the C rating of The Great Planes Lipo 3S 1050mAh 11.1v battery? It says it has 11.7wh. How do you convert watt hours to C rating? Or how many amps does this battery produce? I tried to figure this out but I got confused. I want to run 1350mAh 11.1v 20c lipos in my Heli-Max Axe CP. Last time they ran it for a few times then the receiver board went out. I replace it then the esc, mixer, gyro caught
on fire. Not sure if it was because of to many amps from the lipo. That was in the original Axe Cp upgraded to run a 3s lipo. Now I have the 2.4 GHz meant to run the 1050mAh 11.1v 11.7wh lipo. Are the 1350mAh 11.1v 20c lipos going to fry this one?

Thanks Eric
C rating, combined with Ah, tells you how many amps the battery should be able to supply. Other than that, C rating has nothing to do with Ah or Wh, and can't be deduced or calculated from them. As others have mentioned, Ah tells you how many amps the battery can deliver for one hour, and Wh is the same thing multiplied by the battery volts. C rating is determined by the manufacturer's testing, and should be stated on the pack. If you multiply it by the Ah of the pack, you get the maximum amps that the pack should be able to deliver.

The battery does not force amps through whatever it's connected to -- the motor, receiver, servos etc. that it's connected to only take whatever amps they want, so using a same-volts battery with more Ah and/or higher C rating should not make your equipment draw more amps and fry. However, if you use a battery with more cells (i.e. more volts) you will usually fry your equipment
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Old Apr 07, 2015, 01:02 PM
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Quote:
Originally Posted by ericlhaase68 View Post
The upgrade was sold by Heli-max and you just hooked it up between the 3s lipo and the mixing board. At the time you were supposed to use a GP 950mAh 11.1v lipo. I used a Flyzone 1300mAh 15c lipo. Batteries never got hot or swelled up. Don't know but going to try again.
What was this upgrade? A link to the description would be great.

Freddy
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Old Apr 07, 2015, 04:11 PM
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You also did not state the C rating for that 950mAh battery the craft was supposed to fly with, if it was rated for a 25C or higher pack and you put a 1300mAh 15C, while your gas tank held more fuel, your fuel line got smaller. Would the inability to get enough power for the demand you are pushing for cause things to heat up ... it doesn't seem like it should, but then bumble bee's and GeeBees are not supposed to be able to fly!
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Old Apr 07, 2015, 08:34 PM
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Not sure of the C rating on the 950mAh either, but I remember there being issues with that lipo from Heli-Max. Maybe fried mixers and receivers? The upgrade was the HMXM2008nst v1.0 Lipo Protection Module (LPM). I attached a picture of it.
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Old Apr 08, 2015, 02:19 AM
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From the description, all the LPM does is sit between the e-board and receiver so that it can gradually reduce the power to the e-board when the battery approaches a critical low voltage. That is to prevent you continuing to run the motors and take the battery below a level which will permanently damage it.

I see that in note 6 is says, "Please take a moment to verify that the polarity of all connections are correct ...." Does that mean that some of the plugs can be put in either way round? Don't just check that the plugs go in their sockets easily; check also where each colour wire should be. Reverse polarity is the classic way to fry electronics.

I see no way the LPM is increasing the battery voltage and, as has previously been mentioned, so long as the voltage stays the same as what the equipment was designed for, it can't force more amps through the devices.
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Old Apr 08, 2015, 09:54 AM
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I see that in note 6 is says, "Please take a moment to verify that the polarity of all connections are correct ...." Does that mean that some of the plugs can be put in either way round?
That is just a disclaimer in case they have somebody on their assembly line or the customer is color blind.
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Old Apr 08, 2015, 09:30 PM
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This is what happened. Also just going to upgrade the Axe cp using the newer 2.4GHz mixing board, direct drive tail rotor, Tactic TTX650 radio and a SLT receiver. Hoping this will work using the 1300 mAh 30c lipos.
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Old Apr 11, 2015, 04:19 PM
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According to the Heli-Max Axe Cp 2.4GHz Manuel the Great Planes 1050mAh 11.1v has a C rating of 15.
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Old Apr 11, 2015, 07:37 PM
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I have never seen or heard of a higher C rated battery ever causing any problems with any of the fliers I know or fly with.
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