More C or mAh ?

[Tony]

Been running 3S 25C lipo series. Now, i want to run with 2S2P lipo in series. So which is better. 7.2v 2S1P 4000mAh 25C = 100amp or 7.2v 2S1P 5000mAh 20C = 100amp

Setup: motor 9xl, esc 125amp, prop x642....

[bwells]

hmmm, damn good question. You were previously running 22.2 volts and with your 2s plan in series gets you 14.8, (you misquoted the volts as 7.2 in a 2s, no biggie). But why drop the volts by half? I'm interested in the second part of your thread as that is a great question and I think I see where you are going and wait to here some responses!!! Previous threads say double the Mah and c rating stays the same and others say c rating increases because of two packs to draw from, never saw a consensus on this though.

[domwilson]

I think it is a good question as well. From what I heard, a higher "C" rating the batteries stay cooler and have better acceleration. But I think it really depends on a whole host of other factors. Including brand, type of useage, average amp draw, expected run times, etc.

[bwells]

Yeah, I reread the thread and penciled it out, still ends up with 14.8 and either 8000 or 10,000 MaH but the C rating is the kicker, I like your idea of cooler and more efficient, I assume cost is higher on the c rating than the MaH

[Ub Hauled]

I'd go with the higher C rate...
lower C rates tend to heat up to get to the same point as the higher C rates do.

[domwilson]

Yeah, I reread the thread and penciled it out, still ends up with 14.8 and either 8000 or 10,000 MaH but the C rating is the kicker, I like your idea of cooler and more efficient, I assume cost is higher on the c rating than the MaH

In series, the mah rating stays the same. The voltage is doubled. In parallel the mah rating is doubled but the voltage stays the same. So in series, 2x 7.4v would be 4000mah @ 14.8v. In parallel 2X4000 mah would be 8000mah @ 7.4v.

[Apples1]

if your a memeber of AMPBA, i asked the same question weeks ago,check it out if you can.

as in AUS we have a 150 gram limit per cell ie. 6s class 900 gram max, as both MAH and C rating increase the weight of the pack i could only do one....but which one?..... it came down to two things, runtime and perfermance, i needed to get 5 laps + 1 in and 1 out lap out of my 6s setup, and 4900mah wasnt just getting so i needed more runtime, but if i could finsh a race with 5000mah or so pack i would go for a higher C rating as this meant i could prop up and gain some speed, thats the catch, Higher C rating seem to give more punch and eveything runns cooler, which is a bonus.

i managed to get Hyperion 5500 Gen 3 35c 3s packs, if i cut the wires a bit shorter i can come under the weight. These packs are brillaint!! @ $113 USD great value and they can handle a 5c charge to boot.

[bwells]

Exactly but what he wants is 2s2p in series which ends up 14.8 and either 8000 or 10,000 at the motor depending on the batts he chooses but I like your and UB Hauled answer to go with C rating over Mah so he should go with the 4000 25C ones I assuming, one sticky question and left up to preference or price and weight.

[bwells]

Apples1, we posted at the same time and your explanation is great. It seems like you would go for a higher C rating than increase the Mah. I hope the original thread maker will see this!

[Apples1]

Cheers Wells

[domwilson]

I am surprised others haven't chimed in on this question yet. This could also be a cost issue.

[Flying Scotsman]

I think it is a good question as well. From what I heard, a higher "C" rating the batteries stay cooler and have better acceleration. But I think it really depends on a whole host of other factors. Including brand, type of useage, average amp draw, expected run times, etc.

Dom correct on all your questions. What boat? Also Tony you state

Now, i want to run with 2S2P lipo in series. So which is better. 7.2v 2S1P 4000mAh 25C = 100amp or 7.2v 2S1P 5000mAh 20C = 100amp

I presume you meant to say 2 2S1P in series. I do not think it would make a difference as the avaliable amps are there in either setup with quality batteries. Cheap batteries at least 25C or higher dependant on Mah

Douggie

[domwilson]

Found this article...http://rcedf.com/?p=41

[Flying Scotsman]

Dom, that article is referring to a parallel setup which will garner much better performance in amps. I presumed the thread was about amps and not voltage drop

Douggie

[domwilson]

Douggie, You are correct, in part. He does mention parallel batteries. But the general information is a good to know.