C-Rating, what does it really mean?

Apr 13, 2012 5 Comments by

Battery manufacturers have made great improvements in the battery C-rating over the years and we modelers have embraced this advancement in technology.    But, is it possible to have too high of a C-rating and can we take advantage of it?  We asked Lee Estingoy from Castle Creations about this and here is what he had to say.

Featured News, John Reid

About the author

West Coast senior editor About me: I’ve been involved with RC aircraft since high school and have flown just about everything. I started my RC career with scratch-building, but now like many pilots I rely on ARFs to get me in the air. My main focus is on pylon racing, aerobats, combat and scale warbirds.

5 Responses to “C-Rating, what does it really mean?”

  1. High Nitro says:

    I’m thinking he got it backwards. A 40c rated battery is twice as much “power” as a 20c. In running 40c batteries there is a MARKED difference over 20c both in response, time of flight, and a no-worry puff factor. They are also heavier, but the weight penalty is worth it. I’ve cooked a pile of 20c batteries in electric helis and EDFs. Not so with the 40s, same times, same airframes.

  2. Jim says:

    he has it correct HN… You are not running 40C when comparing apples to apples. A 20C pack will not discharge at 40C because it will overheat. What Lee is saying that if you discharge at the highest C rate that the battery lists, the higher C rated pack will discharge faster than the same capacity and voltage pack but had a lower C rating. Of course if you run a 40C pack at 20C, it will perform better than a 20C pack at 20C.

  3. High Nitro says:

    “Of course if you run a 40C pack at 20C, it will perform better than a 20C pack at 20C”

    Isn’t that what we care about? .40C gives a longer run time, more power, runs cooler, and doesn’t puff — running five minutes in a Stryker Q, with half the flight at full power. That’s a 480 motor, 60 amp ESC, turning 21,000 RPM. Try that with a 20C, or even a 30C. So what does the “C” rating mean in the real world? More “power”? Better longevity? Greater burst? I don’t care at all about running full blast at the C rating and getting a lab result. All lipos puff or worse if they are abused. If you limit your wide open runs to 10 seconds or less, are careful with time management, charge at 1C, you can get 100 or even more runs. I haven’t had any trouble with Turnigys, Nanos, Thunder Power, and others when I follow the rules. And I’ll take a 40 or 50C anytime over one rated less in any environment. Isn’t that the point of putting a rating on the battery?

  4. Tom says:

    40C does not necessarily give a longer run time. At one point in the video it was mentioned that the C rating pertained to the internal resistance of the battery. This point should have been stressed. The higher the C rating, the lower the internal resistance. What this means effecitvely is that less power is dissipated inside the battery as heat. Any power not wasted in battery heat is power available to the motor. Whether or not this results in longer fun time depends on flying habits. To that end, choosing a C rating many times comes down to personal preferences. There are other planes besides jets and helis. If I fly in a manner that doesn’t require sudden acceleration (like a vertical pullout from a 3D hover or high speed passes) I may not benefit from a high C rating. Why pay for it? Also, higher C rated batteries seem to be a bit larger and heavier for the same mah capacity, and this could be something to consider as well.

  5. Basilis Zolotas says:

    40C means 40x Capacity,so a battery of 2200mah max40c can deliver max 2.2amps x 40 =88 amps without damaging the pack
    a 40C batterry of the same capacity and voltage of course,is just stronger than a 20C battery that all,so simple!
    a 2200mah 20c pack delivers 44amp where as a 40C of the same capacity can do 88amps,nothing too complexed…..

    of course abattery of 2200mah 20c and a battery of 3300 20c wont have the same power and longevity,itw 44 vs 66amps max,so the second one will be less stressed in flight with the same power system and work better and longer…

    then there is the manufactirer factor of course
    a cheap battery stated as 2200mah 20-30c might be a bloated number, of a 2000 15-20c,manufacturers do play with allowed 5% deflection in numbers
    ull be surprised if u try 2 packs of the same ratings but of different quality….my 2200mah 30c zippy is by no means as strong as my gens ace 2200mah 25c battery!!

    i hope i helped :)

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