I have always used 25C batteries (I think). Is there any reason that a 20C wouldn't work?
Come to think of it - I really don't know much about C ratings at all.
I have always used 25C batteries (I think). Is there any reason that a 20C wouldn't work?
Come to think of it - I really don't know much about C ratings at all.
"He who turns himself into a beast gets rid of the pain of being a man. I became the God Damn Honey Badger."
Amazing what a single second of searching can yeild...
We hear it from the grizzled veteran pilot who is been flying since he lived next door to Wilbur and Orville Wright. We get the same question from guys who have with so little experience with electricity they think that Watts is just a neighborhood in L.A.
So what does the C rating on a lipo mean? For starters, the C in C Rating stands for capacity. To break it down to its simplest terms, the C rating is the maximum safe continuous discharge rate of a pack. If you see 10C on your battery, it means it can be discharged at 10 times that pack's capacity. Capacity refers to the milliamp-hour rating of the battery, which will be listed as a number followed by mAh (2000mAh, for example).
Here's the easy way to find your battery's discharge rate just multiply the number from the C rating by the pack's capacity. Keep in mind that 1000 milliamps equals one amp. Here's an example, using an 11.1V 2000mAh 10C
11.1 volt 2000mAh -10C
2000 milliamps = 2 amps
2 Amps x 10 = 20 amps continuous discharge
This means that you can safely draw up to 20 amps continuously from that 11.1V 2000mAh 10C without doing damage to your battery. Our packs have all the discharge information printed right on the label. You can check out one of our labels right here. We hope this helps clarify the most misunderstood aspect of electric flight.
"He who turns himself into a beast gets rid of the pain of being a man. I became the God Damn Honey Badger."
So the short answer is - on my Swift for instance - which only draws 20 something amps - a 20C 2200mah battery is more than fine. However - that same battery on (say) my EZ which draws 46a at WOT would likely cause something of an issue.
"He who turns himself into a beast gets rid of the pain of being a man. I became the God Damn Honey Badger."
Looks like you answered your own question pretty comprehensively.
Rules are for the obedience of fools and the guidance of wise men.
Igor Sikorsky - "Gentlemen, there will come a time in your career when you discover that the facts and the theory do not agree. At all times, I urge you to respect the facts!"
Yes, and you'll also want to remember that some batteries (especially cheap HK brand batteries) may not live up to their advertised C-rating.
Personally I always like to give myself a bit of breathing room. If my power system uses 30A at WOT, then I'll want at least 40-50A safe continuous discharge. Is it really necessary? Probably not, but I prefer to err on the side of caution.
OTOH, higher C-ratings typically mean either physically larger or heavier batteries (Not to mention a lot more expensive), so if you're only using 20A on your power system then using a 45C discharge battery will do nothing more than hinder your flight performance from larger/heavier batteries that aren't really needed.
Far better is it to dare mighty things, even though checkered by failure; than to take rank with those who neither enjoy much or suffer much, because they live in the gray twilight that knows not victory nor defeat.
I generally do a little overkill on my batteries. I'm using 20c Turnigy 5000mah batteries on my skywalker and draw at most 35 amps. So far no issues.
One other thing to mention about higher C rated lipos....
The more a lipo can discharge (C) the higher the voltage will be under load.
If you matched up a 10C and a 50C lipo and put them under the same load, the 50C will deliver higher voltage (less sag) than the 10C.
If you are going for all out performance, this may be there difference in a few MPH due to the motor getting that higher voltage (kv). But the cost is weight. higher C rated packs are much much heavier than their lower C counterparts.
We all know that lipos have a quick voltage drop at or near full capacity use. This happens much faster on a higher C pack. This can be great for some.....and destructive to others. It all depends on how hard you are flying your lipos.
Last edited by GregSilver; 18th May 2012 at 01:20 PM.
Weight is important - the ones that I bought are for my fleet of Swift II's - I don't usually push the limits too far with them and the amp draw is pretty low.
My EZ that has the 6000mah pack is 45C.
"He who turns himself into a beast gets rid of the pain of being a man. I became the God Damn Honey Badger."
Shame on you....Originally Posted by Blue Chip
FPV is not a crime!
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2 miles and 6000 feet has been satisfying enough on those little things. Even though I am going for 4 miles and 10K feet to set a record.
"He who turns himself into a beast gets rid of the pain of being a man. I became the God Damn Honey Badger."
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