I have been wondering about this for a while and figured tonight would be as good a time as any to do a little test. I have a couple Lipo batteries that probably won't be used for a month or two, so I just charged them and now ran them down to about 3.75v per cell for "storage". Well, as I was doing this I though why not compare the perforance of different "C" rated packs and see how much of a difference it actually makes. The vehicle I was running for this test was my Losi 8ight-T 2.0 that has a Mamba Monster ESC and a Nue 1518 1800kv motor. I have it geared at 17/50 which I figured was good for about 50MPH or so (I have this set up to run cooler and more conservative than my 8ight buggy which is gear for top speed runs at 26/43 LOL!). The first set of batteries I tested was a dual 3s lipo setup. The batteries are Turnigy 3s 5000mah 20C constant/30C burst run in series for 6s. These pack are almost new with only about 4-5 runs on them. I have a Garmin Forerunner GPS that I use for speed runs so I used it to test my top speed with each setup. The Turnigy batts gave me a top speed of 52.2 MPH which calculates to 35,5xx RPM. The next battery setup I ran was a SkyLipo 6s 5000mah 40C constant/ 80C burst. This setup gave me a top speed of 54.3 MPH and 37,0xx RPM. Both battery setups where barely warm to the touch after about 8-10 minutes of runtime the wires on the 20C batts were a little warmer than the wires on the 40C batts. But there was barely a significant difference. I also was checking the voltage every minute or two since I was wanting to get to a specific voltage of 3.75v per cell for storage. I didn't start doing speed runs untill the batts were just under 3.9v/ cell. I did make sure the voltage was the same with both battery setups when doing the runs so everything could remain consistant. I did do one run with the SkyLipo when it was at full charge and it hit 56.7MPH but that really is irrelevant to this test.

I like information so that is all this test provides. I really don't care about top end speed with this truggy but I like to know what it is capable of and how much of a diffrence little changes make. You are free for form your own opinions about how your truck should be setup, but higher "C" rated batteries are more expensive so knowing how much of a performance gain you will see for the money you either spend or save can be nice to know. I will add that with both battery setups the truggy would do backflips at over 10MPH without any trouble no matter which setup was used! I was sligthly conserned that the 20C batts wouldn't provide enough juice to power this sytem but apparently they are more than capable.

C X mah is continuous amps, mostly important for mid to high rpm running, a battery with a very high burst rating will give you extra punch to get up and go.

if your system will eat more than the batteries continuous rating all the time, it is going to limit your top speed, the life of the battery and the life of the entire system.

my way of thinking is the motor should run warm and not hot, and the battery and ESC can supply at least 1/3 more than the motor's maximum current draw, and the battery should always supply more than enough amps than the ESC can draw.

alot of ridiculous C ratings out there are mostly marketing and the sign that battery technology is improving, stupid high C-ratings are usually pointless.

in the end, if the motor doesn't need extra amps, it wont use extra amps, and the amps just go unused.

That not entirely the case.....

Yes u need to match the current to the actual burst current ur setup draws, but both batteries u have are above that.
So why was the batteries with the higher c rating faster...... Voltage drop under load.

Voltage drop under load is what makes a 7.4v lipo feel faster than a 8.4v setup on a brushed setup.

Surface voltage is so different from load voltage, and that's what makes a good batterie it can even give a interaction of the battery's health.

Let's do the maths... U have a 1800 kv motor running 6s 22.2v 4.2v per cell.max, tested on 3.9v per cell
Turnigy 3s x2 6s 5000mah 20c, 100a
Sky lipo x1 6s 5000mah 40c, 200a
It's safe to say ur setup if not pulling over 100amps.... Scary to thing the 35a ezrun combo puts out 190a burst.. But it's only 2s max
Highly recommend getting on of these... I'm gonna order one Turnigy have a re badged version
http://www.himodel.com/electric/G.T....yzer_130A.html

Turnigy 52.2mph 35,500rpm
3550/1800=19.72/6=3.29v that's a approximate drop of 0.61v per cell
Sky lipo 54.3mph 37,000rpm
37000/1800=20.56/6=3.43v that's a approximate drop of 0.47v per cell

The theridcal top rpm of
22.2x1800=39960rpm so it's close....

A good test would be to try 2 of those sky lipos wired in parallel.... It might get very close to that 39960rpm, but because of weight, rolling resistance and wind resistance u won't eve hit that... But it's possible to get close...

Good post above, but it's not simply about passing the 'requirements'. Higher C rating does provide fringe benefits above whatever is required. A higher C rated battery will be more consistent, especially toward the end of its duration, will deliver noticeably more punch off the line and better midrange response as phmax said.

A simple analogy for batteries is that they are a like a water reservoir, with mAh being the amount of water in the reservoir, voltage being the strength of the pump, and C rating the thickness of the piping that delivers the water.

Thanks m8....

It Just goes to show how overrated 90% of the brushless systems are... I can understand these high amp ESC for boats but for cars its just rediclius. I'm planing to get one of those amp meters and do some futher testing.... Im so tempted to try a ezrun 35a hot box on 4s.... Wonder how many volts can be pumped it to one.
My slash gets just over 60km/h on a 2s lipo, so if I could say run 4s and gear down to the same speed, the amp draw would be a lot less, and so would the voltage drop under load.... With the same mah rating I would have even longer run times....

I honestly think people don't understand there setups very well. I've been hearing a lot of talk abou running 6s.... But 6s is no faster on a 1800kv motor than 3s on a 3900kv motor, bet alone a 4300kv motor... But higher voltage setups with lower kv motors don't loose as much energy through heat, so there for are more efficient... And draw less current...
With in a few months I should have some tests finished and will post up some results on voltage drop, current draw, and battery c ratings

problem with alot of people is instead of gearing down to run a higher voltage battery to run more efficiently, is that they keep the gearing the same and overtax the whole system, they then pick up the burnt up R/c go inside and cry about it over the net.

i still like medium KV and medium voltage the best.

Exactly, if u dont gear down a bit, it will over heat the system causing the magic smoke