john stones 1 - Moderator Posted August 8, 2014 Share Posted August 8, 2014 Not been doing electric flight that long but have managed to get my head around it, and not set fire to anything yet When selecting a lipo for a model, there are different C's and bursts, how do I choose which C rating best suits what I need ? John Quote Link to comment Share on other sites More sharing options...
Ben B Posted August 8, 2014 Share Posted August 8, 2014 Multiply amp hours by the C rating and you get max ampage. Most burst C ratings are way overly optimistic and the lipo will cry uncle long beforeyou get there. Stick to the lower C and you should be fine with all but the cheapest packs... Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted August 9, 2014 Share Posted August 9, 2014 e,g 2200ma/h lipo is 2.2a/h. At 25C the battery is capable of supplying 55amps, (2.2a/h x 25c) At 30C it can supply 66 amps. (2,2a/h x 30C) If your setup is drawing say 70 amps you would need either a higher capacity battery or higher C rated battery. You would also need to keep an eye on the capacity though because although the 2200mah 25C lipo can supply 55 amps it can only do so for approximately 1.98 minutes! Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted August 9, 2014 Share Posted August 9, 2014 I don't understand why, when seeking more amps capability from a battery, people seem to automatically go for higher C rating: As has been pointed out, amps capability = Ah x C, so increasing the Ah will give you the same result, plus longer flight duration. Maybe the answer is that more C adds less weight to the pack than more mAh does -- has anyone done a comparison? Personally I try to size my packs so they're running at 10C or less on average. Some in my larger models give me in excess of 15m flight time, which means they're averaging only 4C. Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted August 9, 2014 Share Posted August 9, 2014 Yes, agree with Alan B. I find that going for the largest capacity that's practical is far more economical than the high C option. I've just got some 3000 20C three cell packs from HK (UK) to replace the 2200s that I was using previously - only twelve quid each, including delivery. Slightly heavier but run times are extended, and even after eight minutes in my Hyperion Yak52 the battery is hardly warm. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted August 9, 2014 Share Posted August 9, 2014 Higher C batteries tend to have a lower internal resistance than a lower C battery of the same capacity, which results in less heat being generated and better performance. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 9, 2014 Author Share Posted August 9, 2014 Thanks fella's I understand that John Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted August 9, 2014 Share Posted August 9, 2014 Yes I would also agree with Alan above on the C rating. Don't go chasing a higher C just to get more amps as the flight time and your wallet will suffer! Much better to upgrade the capacity and as above aim for around 10C in normal flight to minimise stress on the battery. Quote Link to comment Share on other sites More sharing options...
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