SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jun 16, 2012, 12:33 AM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
Discussion
Motor not performing to specs?

Finally got my Rx's in today and installed it in my PZ Extra 300 all geared up to fly it tonight. I hooked the watt meter to it to verify everything was ok with amps, etc and was shocked. The motor I got for it should of been more then enough to do anything I wanted to do or so I thought. It's this motor http://www.headsuprc.com/servlet/the...ushless/Detail rated at 72oz thrust at 39amps and up to 570 watts. I got the 50 amp ESC and 12x6 for it as well to start with. It was only pulling 27 max amps and 305 watts. Something sounds off. My Trojan with a smaller motor pulls 38 amps and 420 watts with a 11x7 so something is wrong. Any ideas??

Here is the ESC. http://www.rchotdeals.com/Products/r.../S50A_BEC.html

Battery is a 3S 2200 25c 12.62 starting voltage

I did notice when I throttle up at about just over half, it acts like its full throttle. In other words the last 1/2 of throttle stick movement does nothing to the motor. I'm lost. Never had this happen before.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 16, 2012, 01:23 AM
GPT
Registered User
GPT's Avatar
Sydney,Australia
Joined Dec 2004
1,601 Posts
Check the throttle calibration, set throttle to full and plug in battery . After the 1st beeps have finished move throttle stick to the off position. Your throttle will now be calibrated correctly.

Refer to the esc manual if in doubt.
GPT is offline Find More Posts by GPT
Reply With Quote
Old Jun 16, 2012, 08:24 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
13,785 Posts
Information from another supplier -

3S LiPo APC-E 12 x 6 (400W) up to APC-E 13 x 6.5 (440W)
4S LiPo APC-E 10 x 5 (400W) up to APC-E 12 x 8 (560W)


As you are using a 3s, you could always go up to the next prop diameter. It will be how the plane flies that determines if you have the right setup.

A wattmeter just tells you you are within safe limits, not how well a model will perform.
eflightray is offline Find More Posts by eflightray
Reply With Quote
Old Jun 16, 2012, 04:59 PM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
Ok thanks. I will try the throttle thing tonight. If that works it will probably be fine because it literally sounds like its not turning hardly at all the way it is. Will post my findings late tonight hopefully. Thank you both again.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Old Jun 16, 2012, 08:52 PM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
I guess I'm going to have to try the 13 inch prop. I did the throttle calibration and gained about 30 watts on the meter but still not where its suppose to be. Since its only at 28 amps WOT on a full battery I should be able to try a few different props without going too high.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Old Jun 16, 2012, 10:19 PM
Registered User
Alameda, CA
Joined Dec 2006
2,924 Posts
The spec says the esc self-adjusting the throttle range. For that price, I think there may be some better choices in esc's, so if you don't get the performance you should from the motor, that may be an option.

I think he is being conservative on propping this motor (he provides the warranty!!), but I
believe you could easily go to 13x6.5. I would try that, while watching the amps.

What is the brand, age, and condition of your battery(s)? What is your voltage at peak demand? If they are well used, a new battery might be all that's wrong.

Hope this helps.

Steve
sgomes is offline Find More Posts by sgomes
Reply With Quote
Old Jun 17, 2012, 01:42 PM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
Quote:
Originally Posted by sgomes View Post
The spec says the esc self-adjusting the throttle range. For that price, I think there may be some better choices in esc's, so if you don't get the performance you should from the motor, that may be an option.

I think he is being conservative on propping this motor (he provides the warranty!!), but I
believe you could easily go to 13x6.5. I would try that, while watching the amps.

What is the brand, age, and condition of your battery(s)? What is your voltage at peak demand? If they are well used, a new battery might be all that's wrong.

Hope this helps.

Steve

The batteries are Blue Lipos. They are fairly new probably cycled 15 times at the most. The batteries perform fine in my T28 so I would think they would be ok for the 300. I thought about seeing if one of the guys at the field has a 4S I can try and see how it does too. I will try the 13x6.5 prop first though. The main reason I used that kind of ESC is they work great in two other planes I have them in and another guy that we fly with runs them in almost all his electric/glow conversions. I guess I pull one of the others out of another plane thats a different brand and see if it changes.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Old Jun 17, 2012, 04:43 PM
Registered User
Alameda, CA
Joined Dec 2006
2,924 Posts
Yeah, sounds like your batts are good. Try another esc, and if the performance is the same, that confirms your original esc.

This would almost surely, then, point to prop size as the reason your amps are down. So, I believe going up to a 13x6.5 should give you what you're looking for.

FYI, a few of us have been using this esc in that size range http://www.hobbyking.com/hobbyking/s...arehouse_.html with very good success. It is currently out of stock in the U.S. warehouse, but in stock in HK. This one has eight timing options, and 5v/6v bec output option. I have pushed them to 55a bursts with no problems. So, if you want options you may want to give this one a try.

Let me know, by pm if you want, how the bigger prop works out, or if you have any further questions. I have done quite a bit of motor testing and am familiar with many motors, so if you are looking for a different motor, I may be able to help.

Steve
sgomes is offline Find More Posts by sgomes
Reply With Quote
Old Jun 17, 2012, 05:32 PM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
If I had found this out sooner I could of ordered one. I just ordered a few things from them last week. lol Figures with my luck.

I think my fiancee's grandpa has some props I can try. Will post back when I get to test them.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Old Jun 17, 2012, 06:10 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,221 Posts
I know it sound like a bit of an insult (it is not meant that way) but I have to ask, are you certain the motor is turning the right direction and that the prop is not on backwards?

And do you know what the voltage was at the time you took the watts reading? I'm wondering if the battery is fading to too low a voltage under load.

Head's Up usually has reliable test data. They only have the current draw on the 3S testing while the 4S has both the current and Watts. It would be nice if they reported both on all their testing.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Jun 17, 2012, 10:43 PM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
Quote:
Originally Posted by jackerbes View Post
I know it sound like a bit of an insult (it is not meant that way) but I have to ask, are you certain the motor is turning the right direction and that the prop is not on backwards?

And do you know what the voltage was at the time you took the watts reading? I'm wondering if the battery is fading to too low a voltage under load.

Head's Up usually has reliable test data. They only have the current draw on the 3S testing while the 4S has both the current and Watts. It would be nice if they reported both on all their testing.

Jack
Well I thought they rated their stuff close to right too thats why I thought it was weird to be getting those readings. I put the prop on like always. Numbers facing away from the plane and the motor is spinning counter clockwise.

Before I started the motor the batteries were reading 12.57 according to the meter. I didn't look while testing though. I can do out again and see I guess. I don't really have a way of checking the thrust rate. Don't have a scale or anything to hook up and test it.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Old Jun 18, 2012, 01:09 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,221 Posts
Quote:
Originally Posted by JoshB View Post
Well I thought they rated their stuff close to right too thats why I thought it was weird to be getting those readings. I put the prop on like always. Numbers facing away from the plane and the motor is spinning counter clockwise.

Before I started the motor the batteries were reading 12.57 according to the meter. I didn't look while testing though. I can do out again and see I guess. I don't really have a way of checking the thrust rate. Don't have a scale or anything to hook up and test it.
And that would be clockwise as seen from the pilot's seat right? Or counter clockwise standing in front of the plane?

I asked because the rest of the numbers did not seem to point to a problem. I'll explain how I looked at them.

You said:

"..It (the 12 x 6 prop) was only pulling 27 max amps and 305 watts...."

Watts = Volts x Amps and both values have to be read at the same moment in time. Most watt meters will present the Watts and either the Amps or Volts, or maybe both, so the unknown can always be determined.

If you read amps and Watts at the same time, your battery was at 11.3V (305W / 27A = 11.3V). And that 11.3V would put your cells and 3.8V (11.3V / 3 cells = 3.75V) and verify that the battery was doing fine as far as it handling the load.

You also said:

"..My Trojan with a smaller motor pulls 38 amps and 420 watts with a 11x7 so something is wrong..."

Again, if the readings were taken at the same time, that would have the battery at 11.1V and the cells at 3.7V. The cell voltages are still OK but about as low as you would want to take the cells under load for the best battery life.

The 11 x 7 and 12 x 6 prop should draw similar amounts of current, the Head's Up testing show the 12 x 6 pulling 4A or about 10% more current.

They list the max current for the motor as 40A for 30seconds, the 12 x 6 gets close to that so if you intend to fly continuous throttle for longer periods of time there may be some overheating. But since you are talking about 3D planes I think you are probably flying at less than full throttle and using full for shorter bursts so that should all be OK

I agree that is sounds like something is not right. If you didn't take your readings at the same time I would recommend you try to do that. And if the numbers still show the disparity you saw an email to Head's Up will undoubtedly be in order.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Jun 18, 2012, 01:36 PM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
Quote:
Originally Posted by jackerbes View Post
And that would be clockwise as seen from the pilot's seat right? Or counter clockwise standing in front of the plane?

I asked because the rest of the numbers did not seem to point to a problem. I'll explain how I looked at them.

You said:

"..It (the 12 x 6 prop) was only pulling 27 max amps and 305 watts...."

Watts = Volts x Amps and both values have to be read at the same moment in time. Most watt meters will present the Watts and either the Amps or Volts, or maybe both, so the unknown can always be determined.

If you read amps and Watts at the same time, your battery was at 11.3V (305W / 27A = 11.3V). And that 11.3V would put your cells and 3.8V (11.3V / 3 cells = 3.75V) and verify that the battery was doing fine as far as it handling the load.

You also said:

"..My Trojan with a smaller motor pulls 38 amps and 420 watts with a 11x7 so something is wrong..."

Again, if the readings were taken at the same time, that would have the battery at 11.1V and the cells at 3.7V. The cell voltages are still OK but about as low as you would want to take the cells under load for the best battery life.

The 11 x 7 and 12 x 6 prop should draw similar amounts of current, the Head's Up testing show the 12 x 6 pulling 4A or about 10% more current.

They list the max current for the motor as 40A for 30seconds, the 12 x 6 gets close to that so if you intend to fly continuous throttle for longer periods of time there may be some overheating. But since you are talking about 3D planes I think you are probably flying at less than full throttle and using full for shorter bursts so that should all be OK

I agree that is sounds like something is not right. If you didn't take your readings at the same time I would recommend you try to do that. And if the numbers still show the disparity you saw an email to Head's Up will undoubtedly be in order.

Jack
Thanks for the incite. Yes it would be clockwise in the pilots seat. I am going to try another ESC and a couple props just to rule everything out and see where it comes out.
JoshB is offline Find More Posts by JoshB
Reply With Quote
Old Jun 18, 2012, 02:51 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,221 Posts
I think that's a good idea, and if your watt meter will allow it, try to note the Watts and Amps or Watts and Volts at the same.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Jul 02, 2012, 11:33 AM
Novice in training
JoshB's Avatar
United States, NC, Statesville
Joined Aug 2011
708 Posts
I tried that other ESC I had and got basically the same results. 11.62v 26 amps and around 300 watts. I did contact Headsup and he sent a new ESC to me. Same thing. I tried finding an instruction manual or pdf to use to program it, but it didn't work. Someone said the factory settings on the ESC are set for inrunner motors and low timing. I might be wrong but from what I know about vehicles timing is too low gives better fuel economy, less performance and higher timing gives better performance but less fuel economy. So in terms of electric it seems it would be less power, and less amps on low and more power/performance on high. The problem is I can't figure out how to change it.

The plane flies ok, but doesn't seem to have the thrust needed to do the things I intended. Hovering, aerobatics, etc. I really dont know what else to try at this point, unless I could find an ESC with more programming options and try it. Its just weird because we have this same ESC on my dads Trojan with a different motor and it works great. Could the motor just not be functioning correctly?
JoshB is offline Find More Posts by JoshB
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Hyperion GS model motor spec missing gofish Power Systems 6 Mar 12, 2012 07:21 AM
Discussion Wading thru motor specs - any tips? shunyata Power Systems 29 Mar 05, 2012 09:33 AM
Discussion BOB mini dvr specs not bad ... ? bakchos FPV Talk 9 Nov 09, 2011 10:06 PM
Discussion Can a DIY Motor Perform As Well as a Mfg'd Motor? rmgmag Electric Motor Design and Construction 111 Feb 08, 2006 07:20 PM
MTM 400-T brushless motor E-flite 370 brushless motor PERFORM ON GWS FORMOSA? Zachary Power Systems 0 Sep 07, 2004 11:10 PM