Testing ESCs - How to?
05-16-2004, 11:15 AM
#1
Testing ESCs - How to?
How can I check an ESC to see if it is "good"?
I have a Novak Dually, bought used - it was very slow... Borrowed a Novak Cyclone - it was very fast - hugely noticeable difference, so I bought the Cyclone that I had borrowed.
After changing the wires on the Cyclone (just to neaten it up a little), it didn't work at all... I found that I had wired it incorrectly, so I assumed I had killed it. When I rewired it correctly, it seemed to run normally.
To verify to myself that the Dually was indeed bad, I reinstalled it, and now it seems normal - swapping between the Dually and the Cyclone, I can't tell any difference, so I don't know if I hurt the Cyclone to bring it down to the "bad?" Dually level, or if the Dually is really OK.
Without being on a track and/or around other cars, it is hard to judge what is happening... Is there any way to test an ESC to see if it is performing correctly?
I have a Novak Dually, bought used - it was very slow... Borrowed a Novak Cyclone - it was very fast - hugely noticeable difference, so I bought the Cyclone that I had borrowed.
After changing the wires on the Cyclone (just to neaten it up a little), it didn't work at all... I found that I had wired it incorrectly, so I assumed I had killed it. When I rewired it correctly, it seemed to run normally.
To verify to myself that the Dually was indeed bad, I reinstalled it, and now it seems normal - swapping between the Dually and the Cyclone, I can't tell any difference, so I don't know if I hurt the Cyclone to bring it down to the "bad?" Dually level, or if the Dually is really OK.
Without being on a track and/or around other cars, it is hard to judge what is happening... Is there any way to test an ESC to see if it is performing correctly?
05-16-2004, 11:20 AM
#3
Yeah, that is a thought. I had planned on sending the Dually back for replacement, but between the two, I want the Cyclone working first. I don't have time to send them both back and have something running by the races this weekend. Escpecially since the Novak site says there is a 2 week lag time on replacing/repairing Cyclones.
Plus, at $35 each (repair), plus what I gave for the Cyclone, plus some batteries that I have committed to buying, I can't afford to do it all at once.
Plus, at $35 each (repair), plus what I gave for the Cyclone, plus some batteries that I have committed to buying, I can't afford to do it all at once.
05-17-2004, 12:10 PM
#4
I talked to Novak, and they said that there is no way to "test" an ESC without lots of expensive equipment...
I guess I will just wait till race day and see if I am way off the pace - or at least see if I can blame being off the pace on the ESC
I guess I will just wait till race day and see if I am way off the pace - or at least see if I can blame being off the pace on the ESC
05-17-2004, 06:50 PM
#5
If you've wired your battery to the Cyclone's motor terminals & powered up... you'll probably have blown the brake FETs. Sometimes the brake FETs can stay jammed on shortcircuit even after you correct your wiring mistake.
If your FETs are burning hot just by powering up... that's a BAD sign.
Don't really need to "test" an ESC, its either working or its not.
For that all you need is 2 multimeters - put a voltmeter on the
battery (input) and one on the motor wires (output). At full
throttle you should have input = output.
Then you can also put an ammeter in circuit with the battery...
check the current drain. At idle the ESC should be drawing
negligible power, maybe just 100mA to power BEC.
Current should rise when the motor spins.
If its pulling several Amps at idle without motor spinning,
you've got a shortcircuited FET.
If you've got access to a sciencelab oscilloscope (sp?), you can
connect the output to the CRO and check its waveforms and how
it changes in relation to RX's signal. But this is probably not
necessary... you'll have known the ESC is working by now.
Most ESC "problems" are caused by bad setup programming.
Best to reprogram them correctly every time something is funny.
If your FETs are burning hot just by powering up... that's a BAD sign.
Don't really need to "test" an ESC, its either working or its not.
For that all you need is 2 multimeters - put a voltmeter on the
battery (input) and one on the motor wires (output). At full
throttle you should have input = output.
Then you can also put an ammeter in circuit with the battery...
check the current drain. At idle the ESC should be drawing
negligible power, maybe just 100mA to power BEC.
Current should rise when the motor spins.
If its pulling several Amps at idle without motor spinning,
you've got a shortcircuited FET.
If you've got access to a sciencelab oscilloscope (sp?), you can
connect the output to the CRO and check its waveforms and how
it changes in relation to RX's signal. But this is probably not
necessary... you'll have known the ESC is working by now.
Most ESC "problems" are caused by bad setup programming.
Best to reprogram them correctly every time something is funny.
05-17-2004, 07:59 PM
#6
Thanks WC - sometimes I can't see the forrest for the trees! I actually do have access to an O-Scope (I work in the Engineering shop of a broadcast TV station), but I wouldn't know what to expect any waveforms to look like, so I don't know if that would help.
Alright - a little testing, and here is what I have found...
Cyclone:
Battery at 7.86V
No throttle - 0.0V to motor
Full throttle - 7.86V to motor
Partial throttle - 7.89V to motor (due to no load?)
No throttle - .002A
Increasing throttle - up to 10A + (my meter maxes at 10A)
-----
Dually:
Battery at 7.75V
No throttle - 0.0V to motor
Full throttle - 7.76V to motor
Partial throttle - 7.76V to motor (again due to no load?)
No throttle - .002A
Increasing throttle - up to 10A +
I don't know about a way to check the brakes, but based on this, wouldn't it be safe to say that both ESCs are "good"? The car seems very fast on the street, but without having other cars to run with as a comparison, I don't know. Since I couldn't send one in and have it back by race day (Saturday), I guess I will wait till then and run each to see how they do - unless anyone can recommend something else to do/try.
Alright - a little testing, and here is what I have found...
Cyclone:
Battery at 7.86V
No throttle - 0.0V to motor
Full throttle - 7.86V to motor
Partial throttle - 7.89V to motor (due to no load?)
No throttle - .002A
Increasing throttle - up to 10A + (my meter maxes at 10A)
-----
Dually:
Battery at 7.75V
No throttle - 0.0V to motor
Full throttle - 7.76V to motor
Partial throttle - 7.76V to motor (again due to no load?)
No throttle - .002A
Increasing throttle - up to 10A +
I don't know about a way to check the brakes, but based on this, wouldn't it be safe to say that both ESCs are "good"? The car seems very fast on the street, but without having other cars to run with as a comparison, I don't know. Since I couldn't send one in and have it back by race day (Saturday), I guess I will wait till then and run each to see how they do - unless anyone can recommend something else to do/try.
05-18-2004, 12:16 AM
#7
The data indicate your ESC's are working fine.
The partial load voltage, is due to the ESC's way of working. It switches the voltage on and of at high frequencies - which your multimeter cant do fast enough, so it senses it as full voltage.
I'm confused about what your problem is;
The way I understand your first post, the Dually make the car slow (top-end, acceleration or both?), while the Cyclone worked fine.
But now I hear that both are working great?
Anyway, WC is right about it's a good idea to re-do the setup procedure, so you can be sure it fit together with your radio equipment.
The partial load voltage, is due to the ESC's way of working. It switches the voltage on and of at high frequencies - which your multimeter cant do fast enough, so it senses it as full voltage.
I'm confused about what your problem is;
The way I understand your first post, the Dually make the car slow (top-end, acceleration or both?), while the Cyclone worked fine.
But now I hear that both are working great?
Anyway, WC is right about it's a good idea to re-do the setup procedure, so you can be sure it fit together with your radio equipment.
05-18-2004, 07:46 AM
#8
Originally the Dually was very slow on top end, and acceleration seemed off too, so I borrowed the Cyclone - it made all the difference... Now they appear equal, so I was trying to determine if I had broken the Cyclone or fixed the Dually....
Maybe the Dually issue was a fluke, or it could have been a programming issue as you mentioned.
Thanks for all the help - we'll see how they do Saturday!
Maybe the Dually issue was a fluke, or it could have been a programming issue as you mentioned.
Thanks for all the help - we'll see how they do Saturday!
05-18-2004, 08:22 AM
#9
Brakes either work or they don't... 
use the 'resistance' part of your multimeter across the motor terminals. Should be infinite resistance when idle, and zero ohms when brakes On.
Oh yeah forgot to add... ESCs control the voltage to motor by pulsing the power - but your DC voltmeter might read this as full voltage. You might get more meaningful readings by using the AC voltmeter section of your multimeter; it depends on the meter's design.
Waveform is a squarewave of frequency whatever your ESC is set to (Cyclone is programmable). At 50% throttle the squarewave should be 50% on (full voltage) and 50% 0V.
Yeah overall sounds like its just a programming glitch... perhaps that time the ESC wasn't giving 100% when your stick's on max.
Only time I've had experience with a "bad" Cyclone was one where the FETs got very hot even when just plugged in. It was drawing heaps of amps at idle and the tabs got stinking hot enough to start melting the orange case.
Takes a lot to kill these things (I've tried). Sometimes funny glitches can be caused by dirt & pebbles in the case, some rocks are conductive and do funny things. Open up and clean out your case insides periodically, give the PCBs a brush too.
use the 'resistance' part of your multimeter across the motor terminals. Should be infinite resistance when idle, and zero ohms when brakes On.Oh yeah forgot to add... ESCs control the voltage to motor by pulsing the power - but your DC voltmeter might read this as full voltage. You might get more meaningful readings by using the AC voltmeter section of your multimeter; it depends on the meter's design.
Waveform is a squarewave of frequency whatever your ESC is set to (Cyclone is programmable). At 50% throttle the squarewave should be 50% on (full voltage) and 50% 0V.
Yeah overall sounds like its just a programming glitch... perhaps that time the ESC wasn't giving 100% when your stick's on max.
Only time I've had experience with a "bad" Cyclone was one where the FETs got very hot even when just plugged in. It was drawing heaps of amps at idle and the tabs got stinking hot enough to start melting the orange case.
Takes a lot to kill these things (I've tried). Sometimes funny glitches can be caused by dirt & pebbles in the case, some rocks are conductive and do funny things. Open up and clean out your case insides periodically, give the PCBs a brush too.
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