Current draw of a 3511KV 5407L with no load on 2s or 3s lipo? Need some help here. - RC-Monster Forums

littlegiant

Current draw of a 3511KV 5407L with no load on 2s or 3s lipo?

I suspect that my feigao has partiallly demagnetised. Right now i am having a current draw of 6A unloaded on 2S lipo. Is this normal?

hemiblas · 07.18.2009, 01:13 PM

That sounds pretty high. I will look later on and I think I have one of those laying around somewhere and a wattmeter. I will try to give a comparison, but usually its only 1 or 2 amps from what I have seen.

zeropointbug · 07.18.2009, 01:32 PM

My 7XL will draw 6.5 amps no load on 6s lipo... so it could be right. Maybe check Fiegao website for idle currents?

littlegiant · 07.19.2009, 12:00 AM

Quote:

Originally Posted by zeropointbug

My 7XL will draw 6.5 amps no load on 6s lipo... so it could be right. Maybe check Fiegao website for idle currents?

Hi, thanks alot for the info. I've tried searching on feigao website but all I have found is the max current spec of the 540 motors.

zeropointbug · 07.19.2009, 12:19 AM

No prod bob.
It's probably right... Fiegaos aren't exactly made with high quality control, so everyone's results may vary a bit.

littlegiant · 12:45 PM

Quote:

Originally Posted by zeropointbug

No prod bob.
It's probably right... Fiegaos aren't exactly made with high quality control, so everyone's results may vary a bit.

I've tested the rest of my motors and found that motors with stator has a lower idle current. Motors without stator cores but have very strong magnets have higher idle current. Higher KV = higher idle current.

Well it all makes sense now. :D

All tested are 2 poles motors.

hemiblas · 07.19.2009, 04:42 PM

Sorry it took me so long. 3.4A on 2S, 5A on 3S.

littlegiant · 07.20.2009, 12:33 PM

Quote:

Originally Posted by hemiblas

Sorry it took me so long. 3.4A on 2S, 5A on 3S.

Ok that's a 5407L right?

I guess my feigao is working fine. Max current draw on a 1/10 buggy was 33A on 3S sounds ok right? Race track will be different I understand.

J57ltr · 07.20.2009, 01:41 PM

So what is the test procedure for idle current?

Jeff

littlegiant · 07.20.2009, 02:25 PM

Quote:

Originally Posted by J57ltr

So what is the test procedure for idle current?

Jeff

Hook the esc up to a wattmeter and apply full throttle. Check the amp reading.

The motor must be without any load (free load)

zeropointbug · 07.20.2009, 02:27 PM

Well, it's a very complex and time consuming procedure, where you take any load off the motor and run the thing WOT and measure the currents using an eagletree or similar unit. Now, this is only for the non faint of heart and experienced RCist.

J57ltr · 07.20.2009, 09:35 PM

Quote:

Originally Posted by zeropointbug

Well, it's a very complex and time consuming procedure, where you take any load off the motor and run the thing WOT and measure the currents using an eagletree or similar unit. Now, this is only for the non faint of heart and experienced RCist.

Well I didn't know, I didn't think you were supposed to run them at full throttle without a load (though I have done it), and idle to me means low rpm.

Jeff

hemiblas · 08:27 PM

Woops, you know what, it an 8L purple feigao. Sorry about that. I can only read the 77A max sticker and the .0076 ohm on it which I think corresponds to an 8L motor. So a 7L would be higher than what I gave you. Ya I just hooked up my wattmeter and let it run full blast for a couple of seconds. I tried a couple times to be sure, but you dont want to run these things unloaded for too long.

33A peak on 3S sounds fine. In fact that might be a bit low. I'm assuming its a light buggy to get that number. But ya looks like it is ok.

littlegiant · 07.21.2009, 12:11 AM

Quote:

Originally Posted by hemiblas

Woops, you know what, it an 8L purple feigao. Sorry about that. I can only read the 77A max sticker and the .0076 ohm on it which I think corresponds to an 8L motor. So a 7L would be higher than what I gave you. Ya I just hooked up my wattmeter and let it run full blast for a couple of seconds. I tried a couple times to be sure, but you dont want to run these things unloaded for too long.

33A peak on 3S sounds fine. In fact that might be a bit low. I'm assuming its a light buggy to get that number. But ya looks like it is ok.

Hey thanks alot. 33A peak on 3S was tested on a low traction surface. Asphalt or grass will definitely result in a higher peak current.

hemiblas · 07.21.2009, 01:06 AM

Something I have learned about the feigao motors is they last forever as long as you cut the run short when they get to about 175 ish. Once they go over that and overheat, they become useless. So watch temps.