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What Does the Lipo "C" Rating Mean?

vortechZ230

Elite Veteran

Michigan, U.S.A.

Can someone please explain the "C" rating of a Lipo battery?, Thanks!

06-05-2008 Over year old.
HOMEPAGE  
Gyronut

rrProfessor

Martinsville In.

"C" stands for the discharge capacity.

For example a 10C 2100mah pack can be discharged at a continous rate of 21 amps for "X" amount of time.

Rick

06-05-2008 Over year old.
speeddemon370

Veteran

Spruce Grove, Alberta, Canada

2100mah (milliamp hours) =2100 milliamps for one hour

10c of 2100ma = 21000ma or 21a

So, if you're increasing you're rated output by a factor of 10 you can generally reduce the time factor by 10 as well. So, 60min/10c=6min

In a perfect world, you should get about 6min of flight from a 2100mah 10c pack running it at it's maximum output of 21 amps. However, it usually dosen't work that way. Experiment around with the math a bit, use ratio's and cross multiply. From there you can start getting a really good indication of what to expect and what you require from you're battery packs.

with 2 ears and 1 mouth you should listen twice as much as you talk

06-08-2008 Over year old.
HOMEPAGE  
"Cam"

Key Veteran

UK

C is for Coulombs

1 Amp, is 1 Coulomb passing a point, per second.

Battery capacities should be written in AmpHours - AH - they’re not, they’re written in mAh.


Multiplying the battery capacity in AH by the C rating (for example 30C) will give you a number in Amps.

3700 x 30C = 3.7 AH x 30 C = 111 Amps

Only charge batteries at 1C unless the instructions say otherwise.

Discharging ANY (good) battery at 10C and it will last for 6 minutes.

DSX9
EMax V2
http://runryder.com/helicopter/gallery/37491/

06-08-2008 Over year old.
"Cam"

Key Veteran

UK

What Speeddemon370 said is correct
In a perfect world, you should get about 6min of flight from a 2100mah 10c pack running it at it's maximum output of 21 amps
BUT you want to run the highest-rated battery you can get because it will hold it's voltage for longer. A 10C battery run at 10C will overheat and the terminal volatge will drop.

Batteries with higher C ratings have lower internal resistnace, so less of the battery's voltage is wasted across itself. You get a much more powerful flight from a 2100 30C than you do from a 2100 10C battery!

SOME new LiPo batteries are OK to charge at 2C. Most only 1C.

Charge a 10C 2100 pack at 2.1 Amps. (1C).
Charge a 30C 2100 pack at 4.2 AMps. (2C) For example.

Never make any assumptions with batteries.

DSX9
EMax V2
http://runryder.com/helicopter/gallery/37491/

06-08-2008 Over year old.
Cambyses

Heliman

Southern Utah

Question, I am new and only fly electric. when you have a say 25C battery it wont always discharge at 25C right? What I mean is your motor wont always pull that much. You could have a 25C battery but only be discharging at 10C right?

06-17-2008 Over year old.
speeddemon370

Veteran

Spruce Grove, Alberta, Canada

Right cambus. 25c would be the maximum that the battery could handle if the motor/esc needed to pull that much. It wouldn't be continuous though.

with 2 ears and 1 mouth you should listen twice as much as you talk

06-17-2008 Over year old.
HOMEPAGE  
ZuhairMarafi

Heliman

Kuwait

Battery Amps

Am new in electric brushless motor and I need an advice how can I calculate the battery amps
Like if I have a motor with 1855 watts 600kv 55amps battery size 14.8- 37v how can I calculate the amps and how can I select the right battery

Thanks

04-11-2012 Over year old.
Richardmid1

rrProfessor

Leeds, England

1855W and 55A will be the motors max continuous power output and current draw.

14.8-37v is 4s - 10s Li-Po.

It all depends on the application and battery voltage as to the average current draw.

You want to be averaging not much more than half the current the motor is rated for so in this case lets call it 30A.

If you wanted the application to run for 1 hour you would need 36Ah (36000mah) (using 80% capacity). To run for 1/2 hour you would need 18Ah. 1/4 hour you would need 9Ah. 7.5 mins you would need 4.5Ah (4500mah).

60% of the time, it works every time!

04-12-2012 Over year old.
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Flyrover

Heliman

Guangdong,China

Agree the above.

04-18-2012 Over year old.
HOMEPAGE  
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What Does the Lipo "C" Rating Mean?

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