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Minimum Battery C Rating

Minimum Battery C Rating

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Old 07-01-2011, 08:52 AM
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Default Minimum Battery C Rating

Ok, I could have sworn there was a thread on this a little while ago-but even I can't find it. Sometimes the search function is... sketchy.

Anyway, I know for 1/8 systems using high voltage low kv (6s 1400kv) it's ok to use lower c ratngs for your battery. But how low?

Would a battery with a higher C rating lets say 3000mah 6s 40c vs a 3000mah 6s 30c battery,

the higher c battery would make the ESC, battery, or motor run cooler? All of them?

What would you guys say is the minimum continuous amps (is this the right word, I forgot, LOL) for a 6s 1400kv battery in buggy?

For example, a 3600mah 30c 6s should have 108 (3.6 x 30c)

I'm looking at getting very lightweight low mah batteries for qualifiers.

6s 2200mah 30c = 66
6s 2200mah 40c = 88
6s 2650mah 40C = 106
6s 2450mah 30c = 74


Thanks guys
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Old 07-01-2011, 09:08 AM
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Originally Posted by Muggydude View Post
Ok, I could have sworn there was a thread on this a little while ago-but even I can't find it. Sometimes the search function is... sketchy.

Anyway, I know for 1/8 systems using high voltage low kv (6s 1400kv) it's ok to use lower c ratngs for your battery. But how low?

Would a battery with a higher C rating lets say 3000mah 6s 40c vs a 3000mah 6s 30c battery,

the higher c battery would make the ESC, battery, or motor run cooler? All of them?

What would you guys say is the minimum continuous amps (is this the right word, I forgot, LOL) for a 6s 1400kv battery in buggy?

For example, a 3600mah 30c 6s should have 108 (3.6 x 30c)

I'm looking at getting very lightweight low mah batteries for qualifiers.

6s 2200mah 30c = 66
6s 2200mah 40c = 88
6s 2650mah 40C = 106
6s 2450mah 30c = 74


Thanks guys
C Rating is a little over blown as there is no real standard to measuring it... hence the BS 90c and 150c claims that are starting to show up. All a higher C rating is going to do in 1/8 on 6s is give an already over powered car way more power than is needed.

You can easily run 20-25c packs with 6s. It might feel a tad less punchy than a comparably 40c-45c pack. However, even with 20c 1400/6s you are going to have way more power than is needed.

Run whatever packs you want and not worry about it. C rating really is more important with the 2s setups, particularly in 4x4 as the batteries are under a lot more strain to supply the needed power With 6s, C rating is almost not even relevant imho.
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Old 07-01-2011, 09:17 AM
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I'm not worried about punch or power, just having the system run cool.

Will a higher c rated battery make the motor, esc, or battery run cooler?
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Old 07-01-2011, 09:27 AM
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Originally Posted by Muggydude View Post
I'm not worried about punch or power, just having the system run cool.

Will a higher c rated battery make the motor, esc, or battery run cooler?
No, higher C rated packs are not going to lead to a noticeably cooler running system.

Generally, higher C rated packs will not get as warm as lower C packs, but I don't think you would even notice the difference with a 6 cell setup since amp delivery is not an issue like it is on lower voltage.

The battery has nothing to do with your motor temps. A free drive train and proper gearing is the key to low motor temps.

Speedo will run cool on 6s since it won't be pulling as many amps.
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Old 07-01-2011, 03:26 PM
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Muggy...check this out...lots of good info about batteries in here


http://www.rchelicopterfun.com/rc-lipo-batteries.html
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Old 07-01-2011, 03:38 PM
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I have run both 30C and 20C 6S lipos on a 1350kv T8 motor and the 20C seemed to temp a little lower on my motor. It may have been a fluke or how hard I was driving though too. There are so many factors. I run 5000mah packs as I need to make long Nitro mains in an E-truggy and I was temping out at 150 with the 20C and 160 with the 30C. Again, this may have been a fluke but that is what happened. So many factors could impact these temps though. And yes, the temps are a bit high but that's after 25-30 minutes etc.
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Old 07-01-2011, 03:49 PM
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The previous posts are correct lower C will run cooler and higher C hotter but more power (usually too much).

2cell = 35C+
3cell = 30C+
4cell = 25C+
5cell = 20C+
6cell = 15C+

Where by those are the minimum "Constant" C ratings you want and the Burst C should be 10-25 more than the Constant. Having more than 20 or 30 C above those minimums and it becomes a waste of your money. Having C ratings lower than these minimums will not only be slower but most manufactures claim a certain minimum (as shown) makes your ESCs run more reliably and that running too low a C can cause your ESC to do weird stuff.
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Old 07-01-2011, 04:01 PM
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Originally Posted by jasonwipf View Post
The previous posts are correct lower C will run cooler and higher C hotter but more power (usually too much).

2cell = 35C+
3cell = 30C+
4cell = 25C+
5cell = 20C+
6cell = 15C+

Where by those are the minimum "Constant" C ratings you want and the Burst C should be 10-25 more than the Constant. Having more than 20 or 30 C above those minimums and it becomes a waste of your money. Having C ratings lower than these minimums will not only be slower but most manufactures claim a certain minimum (as shown) makes your ESCs run more reliably and that running too low a C can cause your ESC to do weird stuff.
Thats not necessarily true, unless you are at the edge of the limit (low) on C ratings, and the motor is pulling too much power than the batteries can provide. If thats the case, temperature would only confirm what you feel on the track - stuttering, lack of punch, etc.

Also, C rating is dependent on capacity. Typically the lower the capacity, the lower the C rating. While I'd like to run a 2500mah 4s, im not sure that the 20-30c rating would be sufficient at that capacity, whereas my 5000mah packs, 20-30c would be fine.


The best advice I can give to people regarding C ratings (as someone said, there is really no telling how accurate they are to begin with), is do a little math, and add in a % for tolerance and inefficiency. Also, if the pack is hot after a run, that may be an indication its near its limit.

Truth be told, these motors we run are capable of large current draw, but not all the time. 100A constant is a LOT, and if your 5000mah battery had to provide that load, it would be drained in 3 minutes...
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Old 07-01-2011, 04:46 PM
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Why would it run cooler on a lower c battery? That doesn't really make sense.
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Old 07-01-2011, 05:02 PM
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I can tell you from personal experience that my castle MMM/1800 runs much cooler on 5s 40c 3300mah sky lipo(second best battery I have used only to team orion carbon molecular) than it did on 4s 30c 5000 turnigy. The 4cell turnigy's were always gettin warm, and when in decided to try the 5s sky lipo's I was shocked at how much cooler the speedo and batteries ran. Just my experience.
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Old 07-01-2011, 05:56 PM
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Did you gear down when you went from 4s to 5s?
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Old 07-01-2011, 06:34 PM
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With Heat on the Motor you have to look at all the factors

The ESC Will only deliver what it can from what the Batteries are willing to put out.

Also the Higher the Voltage the Higher the Efficiency of the system and the Lower the current draw.

Lower the Current you effectively lower the capacity to create wasted energy in the form of heat.

Ohms Law is v=I*R The resistance is the system resistance as a whole not just the motor.

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Old 07-01-2011, 06:35 PM
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Originally Posted by symmetricon View Post
I can tell you from personal experience that my castle MMM/1800 runs much cooler on 5s 40c 3300mah sky lipo(second best battery I have used only to team orion carbon molecular) than it did on 4s 30c 5000 turnigy. The 4cell turnigy's were always gettin warm, and when in decided to try the 5s sky lipo's I was shocked at how much cooler the speedo and batteries ran. Just my experience.
That makes complete sense. I believe you were cooler on the 5s 40c 3300mah. Even though it was 1cell more and 10C on average it was still 50grams lighter (40-65 grams depending on the manufacturer) because you've dropped 1700mah and because it was a 5s with its higher voltage it was even more efficient. You had 2 things going for you being cooler there. if you ran a 5s 20C (instead of 40c) 3300mah in the same brand I guarantee you will be EVEN cooler yet and plenty of power as long as its 5s

My last posting was a general guild and pretty solid you can rationalize finer points all day but that will get you where you need to be.

Last edited by jasonwipf; 07-01-2011 at 07:06 PM.
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Old 07-01-2011, 06:38 PM
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Originally Posted by jdeadman View Post
With Heat on the Motor you have to look at all the factors

The ESC Will only deliver what it can from what the Batteries are willing to put out.

Also the Higher the Voltage the Higher the Efficiency of the system and the Lower the current draw.

Lower the Current you effectively lower the capacity to create wasted energy in the form of heat.

Ohms Law is v=I*R The resistance is the system resistance as a whole not just the motor.

good post. I like the way you put it. By current do you mean constant C amps being lower with higher voltage I presume.

Last edited by jasonwipf; 07-01-2011 at 07:07 PM.
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