Amp and ESC basics...

[protyne]

I'm using a 20C battery which specs states 45amp constant.

A 25A ESC allows 25A amp draw constant bursting up to 40A. Does it mean the ESC cannot be used? Or it doesn't work that way?

Cheers

[baby_zyklon]

Those are just rated spec. They are nothing without the motor rating and actual motor amp draw. To put it simply, the amount of amp that is drawn is decided by your motor.

[glenn cain]

and you must have a esc with a higher amp rating than your motor or you will fry it. eg for a motor that draws 30 amp, you would need 30a or better still 35a to safely use it.

[protyne]

Thanks! I think I get it now.

So the ESC Amp rate must be higher than the motor's spec. Batteries just provided the punch of which how much can be sucked still depends on the motor's drawn amp ya?

Thanks again

[flying bear]

hi,

i think a higher C battery do make a differences in the power output of the motor. as it is able to substain higher voltage. with the same current output.
So more power. I always see a differences when i used the flight 25C battery compare to the rest of 15C batteries. Datas from watt meter tell me the reasons. I estimate abt 5-10% differences unless u need that last burst for competition.

Bear

[Babylon5]

about ESC, amps and motor

Hi , I have heard many times that flyer mentioned motor quit half way during flight.
Usually (with exception)the motor brushless motor don't quit first but is the ESC that cuts off. This usually happen when flyer use oversize/pitch prop on high KV motor resulting is very high current during flight. The ESC gets over heated not at max power but somewhere in the middle to 3/4 max power. So Flyer gets puzzle and jump to the conclusion that the motor is "lousy" when half power ,motor already cut suddenly.
Infact they are lucky, the ESC is well design that when it overheat, it cuts or reduce outage ....otherwise, the entire ESC would have smoke and bring down the entire plane.

The only times when the motor quits is when the ESC don't cut(very high rated ESC is used) , the heat is so high that it causes the adhesive that holds the magnet inside the motor to de-natured and then you have exploding magnet. The other failure is the enamel insulation starts to break down and cause internal short.

Therefore if you want your motor, ESC, battery to last longer ,get yourself a clamp on ammeter, measure the amps . Start with a small or lower pitch propeller.
Don't exceed the max ratings of your electronics and electrical stuffs.
Remmember, ESC runs hotter somewhere between half power to 3/4 power and not at max power.


Cheers and best of luck.

[slackerz]

Not just that, if you draw higher Cs than your batt C rating, you'll fry your batt, it WILL catch fire.

[detach8]

i think the battery, esc and motor, even your wires and connectors are part of the equation to the power you want to provide for your craft

basically it's a good idea to work backwards... like if you want crazy power then you may think a high torque or high kV motor would be a good idea.

then you will check out the amp rating and choose a suitable ESC that can provide such current, and at the same time allow some buffer to prevent your ESC from burning.

then lastly you go to your battery and find out if it can sustain the current draw by your ESC.

if all three balances well, and provided you choose a correct prop (i have no knowledge of prop, however.. i fly helis haha) then your motor, esc and battery should run warm and not overheat. if you get any of these equation wrong.. something would overheat.

and usually the overheating component is the one causing the "bottleneck"... that's what i feel

it's quite tricky for the motor tho.. if the motor overheats, it might not be that the motor is weak. it may be just your prop size, pinion T, blade pitch.. whathever else that is mechanically linked to the motor that is causing it to heat up.

[fieldburt]

Hi,

I am a beginner using a align 35A ESC that came with my Trex. Was 1 min into the flight and the ESC power cut came in. This happened several times throughout 1 battery flight i.e. power cut happens every 1 - 2 min of hovering. My motor is the align 430L (think its 3550kV?) that came standard with the heli, so I am guessing the reason couldn't be a mis-matched motor + ESC combination??

My pitch and throttle curve as follows: PC 0,40,60,75,90 and TC 0,35,65,80,95.

I was reading the ESC manual and several possiblities:

1) Battery protection circuit came into play when I exceed 65% of my battery voltage (btw, i was using a NEW 2200mah, 20C, 3 cell. So this is the first charge and first flight!! )

2) The other possibility might be the thermal protection coming into play. My ESC is stapped on externally on the side of the frame. Where else might have better ventilation?

As I am only a beginner, I am only doing hovering thus far... not even FF and I am already "tripping" the esc? strange .. would appreciate some input and advise from the gurus here.

Cheers