Measuring Voltage Coming out of an ESC

Thread Starter

HobbyGuy10

Joined Aug 19, 2021
4
Hello,

I have an ESC which is rated for 40A. I want to make sure that the 3 phase motor to which it is connected is getting sufficient voltage. How do I connect my multimeter to the ESC to measure voltage correctly? Should I just run the ESC at 80% PWM and measure 2 of the 3 outputs from the ESC? I once heard that you could short the ESC and/or the multimeter if this is done incorrectly so I thought I would make sure I was doing it right before connecting anything.

ESC: https://hobbyking.com/en_us/ztw-spi...pto-multi-rotor-esc-2-6s-simonk-firmware.html
Motor: https://hobbyking.com/en_us/4112-32...-multi-rotor-motor-with-extra-long-leads.html

Thanks!
 

LowQCab

Joined Nov 6, 2012
1,189
The problem is, You don't understand what is going on.
If You suspect that an ESC is "bad",
the solution is to buy a second one, and compare the performance differences.

You can't really get any meaningful information from an ESC with a Meter.
The ESC will either do its thing, or it won't.
There is virtually no situation where the ESC only works "part-way".

You "might" get some useful information with an Oscilloscope,
but I am fairly confident that You are "barking-up-the-wrong-tree".

There a huge pile of other things that must be in-order for the System to work.

You need to state what the over-all problem is that You are having,
not necessarily the problems You are having with the methods that
You have chosen to try to figure out what You think the problem may be.

More than likely, your problem has nothing to do with the ESC.
Generally, ESCs are pretty-much bullet-proof,
except when it comes down to proper Amperage sizing, and rejection of Heat.
Completely wrapping your ESC in Shrink-Tubing is a sure-fire-way to smoke it.

Did You start-out with a standard , plain-vanilla, set-up,
and then change something,
and now you're wondering why it didn't have the desired effect ?
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Martin_R

Joined Aug 28, 2019
103
If you want to check properly what's going on with your setup you need one of these
https://hobbyking.com/en_us/turnigy...D=42854&indexName=hbk_live_products_analytics
It will check your battery voltage on and off load, the current the motor is drawing and the wattage consumed by the system.
As already said by LowQcab, ESC's either work or don't.
Is your transmitter properly setup? Is your battery up to supplying the load? Is the propellor the correct size for the motors kv rating?
 

Thread Starter

HobbyGuy10

Joined Aug 19, 2021
4
If you want to check properly what's going on with your setup you need one of these
https://hobbyking.com/en_us/turnigy...D=42854&indexName=hbk_live_products_analytics
It will check your battery voltage on and off load, the current the motor is drawing and the wattage consumed by the system.
As already said by LowQcab, ESC's either work or don't.
Is your transmitter properly setup? Is your battery up to supplying the load? Is the propellor the correct size for the motors kv rating?
Thank you for the reply. Regarding the watt/ power meter you linked above, would I be able to connect this between the ESC and the motor?

I have already verified that everything up to the feed of the ESC is working correctly and the ESC is receiving a full 24V. My command signal (transmitter) is also working correctly. My battery is fully charged at 24.5V. The propeller / motor combo along with pretty much an identical setup was used by a colleague and he is getting a much higher RPM.

So there is only two ways my colleague and I are getting different RPMs:
1) My motors are not getting full voltage from the ESC.
2) My colleague actually has a different motor in his setup but is confused and told me that our motors are the same.

It's starting to sound like the latter is more likely, but a measurement of what voltage the motor is getting directly from the ESC output would confirm this I think.
 

Martin_R

Joined Aug 28, 2019
103
Regarding the watt/ power meter you linked above, would I be able to connect this between the ESC and the motor?
NO! The meter connects between the battery and ESC.
Are you checking the battery voltage off load or when the motor is running full load? It can be the battery has high internal resistance and the voltage drops under load, the above meter will show that.
Is your motor the same kv rating as your colleague? Kv is the rpm per volt, and maybe your setups are different.
 

LowQCab

Joined Nov 6, 2012
1,189
There are probably 3 or more different settings that can affect
the maximum output of a Motor / ESC combination.

More RPM's ..........
Come on man,
How do You know exactly ?
Are You flying side by side and Data-logging everything ?
Do your Quads weight exactly the same ?
Do you have the same Frames ?
Are every single one of your 30+ Tuning-Parameters EXACTLY the same ?
Are both of Your Batteries brand new and the exact same part-number ?
Are You both sharing a single Battery Charger ?
Are You sure your pal is not messing with You and feeding You misleading info ?
The list goes on ............
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Thread Starter

HobbyGuy10

Joined Aug 19, 2021
4
There are probably 3 or more different settings that can affect
the maximum output of a Motor / ESC combination.

More RPM's ..........
Come on man,
How do You know exactly ?
Are You flying side by side and Data-logging everything ?
Do your Quads weight exactly the same ?
Do you have the same Frames ?
Are every single one of your 30+ Tuning-Parameters EXACTLY the same ?
Are both of Your Batteries brand new and the exact same part-number ?
Are You both sharing a single Battery Charger ?
Are You sure your pal is not messing with You and feeding You misleading info ?
The list goes on ............
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Can we try to be less condescending? I really do not see the need to be rude.

Anyway, your assumptions are all incorrect. I figured out what the problem was and it had nothing to do with any of the things you mentioned and my system was indeed running at only 50% of its rated RPM as per supply voltage and kv. Try to be a little more open-minded next time. People come here for help, but with an attitude like yours, few will be coming back.

P.S: For the love of god, do not capitalize the first letter in the word "you".
 

Thread Starter

HobbyGuy10

Joined Aug 19, 2021
4
Just for my interest, what was the solution to your problem?
The ESC has a very specific throttle calibration sequence which I probably didn't do properly the first time. The ESC needs to be in initialization mode and then you would have to rev up to 100% PWM, at which point you should connect the battery, then back down to 0%. This allows the ESC to calibrate itself and recognize what scale it can run within. It appears whenever this calibration was completed, I did not properly rev up to 100% PWM, and instead only went to 50%. Meaning that the new range the ESC has access to is 0-50% instead of 0-100%. So when I set my PWM to say 0.5, I am only getting 25% of the RPM, or 50% of 50%.

In short, I had to re-calibrate my ESC and now everything is working as it should.
 
Last edited:

LowQCab

Joined Nov 6, 2012
1,189
I'm happy to have been of some assistance to You, even if You didn't "like it".

Thank You.

I am never condescending, or rude, or make ad-hominem attacks or call names,
if You choose to interpret it that way that's completely your business.

You have started the Thread with very little information,
and only refer to what You currently think the problem might be,
without informing anyone of the normal list of settings and set-up procedures
that You have, or haven't checked yet.
So it's up to someone else to take their time to attempt to get You to
clearly state exactly what efforts You have put towards solving the problem yourself,
which was apparently, not very much.

How much did You pay to have someone with more experience pick your brain
and to get You to realize how You can avoid having this type of situation re-occur ?

It's very possible that You could have thrown away serious Money, Time and
suffered hours of frustration without this freely given assistance.

Your buddy was either, unable, or unwilling to help You with it,
but You got professional assistance for free here,
and now You want to act all "offended".

I'm happy to have been of some assistance to You, even if You didn't "like it".

Thank You.

Oh and BTW ...........
"You" is a "Proper-Noun" and is supposed to be capitalized.
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