Power Systems Talk about motors, ESC speed controllers, gear drives, propellers, power system simulators and all power system related topics

Motor cutting out

Old 09-24-2011, 06:12 PM
  #1  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default Motor cutting out

Hi

I just returned from a first flight of my Frsky system. I converted my old 6exa using the Frsky hack module. No problems doing this and everything works as it should (I think).
As a test bed I installed it in my Easystar which had always used a JR slimline receiver on 35MHZ.
What happened:
At no time did I loose control or feel that I had. Twice the motor cut at full revs. I still had control of elevator and rudder although my instinct was to shut down the throttle as soon as the motor cut, I may not have had that contol if I kept the stick fully forward -I just do't know because as soon as I increased the revs again away she went.

I am wondering if the 2.4 receiver is taking just a tad more current than the JR and the esc is shutting down. ( once or twice on 35mhz the motor coughed for a second or two but never cut completely) The Frsky re-connects the radio link in a fraction of a second so it is difficult to say if this was signal loss but I just cant see that. I flew as far out and as high as I ever want to and that made no difference to the motor cutting problem.

I am using a Pilot 20A esc with bec on the std 400 motor powered with a 7.4 2500 Mah lipo 20c. The same system I have in a twinstar with two of these motors and never a cough.
When I just checked the lipo still had 45% charge left.
It is slightly puffed and this has never happened before. Could this be because of the low temperature today?

Well there is may essay........... Any thoughts?

BTW
I am well pleased with the Frsky system and it cost less than 30 to convert my 6xea . Even the bind panel fitted perfectly into the crystal socket on the rear of the case.

Pete
cheshireflyer is offline  
Old 09-24-2011, 06:34 PM
  #2  
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 6,122
Default

Seems to be that the battery voltage under heavy load is dropping too low and activating the ESC's low voltage cut-off (LVC). Closing the throttle re-setts the LVC and gets the motor going again, this is normal. The fact that the battery is puffed is further evidence that it's on it's way out.

You could verify it if you have a wattmeter or multimeter to record voltage under load. Most ESC's activate LVC at about 6 -6.3V for a two cell pack.

If this is the case then the only answer is to get a new battery.

Steve
JetPlaneFlyer is offline  
Old 09-24-2011, 07:24 PM
  #3  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default

Originally Posted by JetPlaneFlyer View Post
Seems to be that the battery voltage under heavy load is dropping too low and activating the ESC's low voltage cut-off (LVC). Closing the throttle re-setts the LVC and gets the motor going again, this is normal. The fact that the battery is puffed is further evidence that it's on it's way out.

You could verify it if you have a wattmeter or multimeter to record voltage under load. Most ESC's activate LVC at about 6 -6.3V for a two cell pack.

If this is the case then the only answer is to get a new battery.

Steve

Thanks Steve.
I said I have the same setup in a TwinStar.........I just thought, I use different lipos in that I use the same one for the easy*

I am never sure what makes a lipo swell. I never over charge and the Easy* only runs at about 60W.
Could be just age although this one must only have about forty flights on it in the same model.

I will try a different lipo and report back. Will pop it on the W meter in any event just for the record.
cheshireflyer is offline  
Old 09-25-2011, 06:54 AM
  #4  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default

Originally Posted by cheshireflyer View Post
I will try a different lipo and report back. Will pop it on the W meter in any event just for the record.

Well I put it on the watt meter before I re- charged the lipo.
Volts were 7.8. I ran the motor at full power for ages and the lipo never went under 7 v. I just could not recreate the fault. I am now wondering if the esc may be on the blink and cutting motor power too early or when the lipo is at full charge giving max. amps the esc cant handle it and shuts down. It is a 20A esc though.

I have a volt monitor attached in the model and this sounds off at 3.3v per cell. It never sounded and both green lights on showed that the cells were above that voltage. After a while the lipo is not puffed. I think it is more to do with the heat shrink not being a ticht fit any longer not the cells actually puffed.
Next move will be to fly again and see if the motor cuts. If it does then I will use another lipo. I will report back as all this may help others. The main reason for using the easy* was to test out the Frsky gear.

My training was in radio TV and electronics. I forgot loads but the important stuff is still in the grey cells ( just beneath the grey hair lol)
Do say if I ramble on too much !
cheshireflyer is offline  
Old 09-25-2011, 09:53 AM
  #5  
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 6,122
Default

Yeah, it could also be the ESC tripping out on overload. How many amps did your Wattmeter record?.. anywhere near the 20A ESC rating?

Low temps do cause voltage to drop but, in my experience, it's got to be pretty cold (well below zero C) before you notice significant changes. And even then the battery soon warms up in use anyway.

Lipos sometimes tend to puff a little after hard use then they may lose some or all of the 'puffiness' when they cool. I assume the cells can give off some form of gas in use which 'inflates' the covering.
JetPlaneFlyer is offline  
Old 09-25-2011, 03:01 PM
  #6  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default

Originally Posted by JetPlaneFlyer View Post
Yeah, it could also be the ESC tripping out on overload. How many amps did your Wattmeter record?.. anywhere near the 20A ESC rating?

Low temps do cause voltage to drop but, in my experience, it's got to be pretty cold (well below zero C) before you notice significant changes. And even then the battery soon warms up in use anyway.

Lipos sometimes tend to puff a little after hard use then they may lose some or all of the 'puffiness' when they cool. I assume the cells can give off some form of gas in use which 'inflates' the covering.
Reading was about 9-10 Amps so well in range. I was off out to test again but rain stops play.
I ran it up in my worshop trying to repeat the motor cut but it just won't.
Just watching the Grand prix. Wish I have the sort of info readout they have

Will try flying again asap and if it has not improved will use a new lipo which I have.
Well its all good fun and keeps the brain active.

Thanks for your support

Pete
cheshireflyer is offline  
Old 09-27-2011, 10:31 AM
  #7  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default

[QUOTE=cheshireflyer;835789]Reading was about 9-10 Amps so well in range. I was off out to test again but rain stops play.
I ran it up in my worshop trying to repeat the motor cut but it just won't.
Just watching the Grand prix. Wish I have the sort of info readout they have

Will try flying again asap and if it has not improved will use a new lipo which I have.

Well I was out again. Tried the same lipo and got same result. Tried a new lipo and again the same. This time I was losing control when I turned off the motor. This was at quite a distance but apparently this Frsky stuff has fantastic range !
On a ground reduced power check I get 20 paces against the stated 30 paces. As I just cannot replicate the motor cutting problem on the ground at close range with motor at full power I need to look at the radio side of things.
cheshireflyer is offline  
Old 09-27-2011, 12:56 PM
  #8  
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 6,122
Default

If you are losing all control then that very much looks like a radio issue. It could be related to the power supply from the BEC in the ESC. If it's just a basic linear BEC, which it's likely to be on a 20A ESC, then it could easily get overloaded and shut down temporarily, or the BEC output voltage could drop leading to the receiver shutting down.

You could check this by using a seperate battery for the receiver or a stand alone BEC.

thanks
Steve
JetPlaneFlyer is offline  
Old 09-27-2011, 01:01 PM
  #9  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default

Originally Posted by JetPlaneFlyer View Post
If you are losing all control then that very much looks like a radio issue. It could be related to the power supply from the BEC in the ESC. If it's just a basic linear BEC, which it's likely to be on a 20A ESC, then it could easily get overloaded and shut down temporarily, or the BEC output voltage could drop leading to the receiver shutting down.

You could check this by using a seperate battery for the receiver or a stand alone BEC.

thanks
Steve
Hi again Steve.

I shall use a seperate RX battery as there is plenty of room in there and I can remove some lead. I am right in saying that I just need to remove the positive plug from the esc lead to the RX ? and then connect a batter to a free channel.

I have also noted on another thread that the test range of the system is just 20 paces and not the 30 stated by Frsky. Things get murky don't they !

Pete
cheshireflyer is offline  
Old 09-27-2011, 01:10 PM
  #10  
JetPlaneFlyer
Super Contributor
 
JetPlaneFlyer's Avatar
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 6,122
Default

Yes, that's how i understand it.. Just remove the red (centre) wire from the ESC to Rx plug. Then plug the battery into the battery port on the Rx
JetPlaneFlyer is offline  
Old 10-09-2011, 07:59 PM
  #11  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default Motor cut problem sorted

Hi

I found the problem. The aerial was not making a good enough connection to the threaded socket on my TX. I made sure that enough thread was showing through and now I have no problems at all and more range than my eyes can stand.

Thanks to all who posted ideas and suggestions.

Pete
cheshireflyer is offline  
Old 11-05-2011, 07:23 PM
  #12  
repinfl
New Member
 
Join Date: Apr 2011
Posts: 11
Default

I am having same problem of motor stalling and when it does it makes a LOUD growling noise! If I advance the throttle slowly this does not happen. This is a Great Planes Eletrostik that came with motor & ESC already installed. LHS has given me a new motor and a new ESC, same problem. I thinking it must be something to do with the battery or connectors. Any ideas?!
Thanks...Robert
repinfl is offline  
Old 11-07-2011, 10:15 AM
  #13  
cheshireflyer
Member
Thread Starter
 
Join Date: Jul 2009
Location: Near Crewe Cheshire England
Posts: 51
Default

Originally Posted by repinfl View Post
I am having same problem of motor stalling and when it does it makes a LOUD growling noise! If I advance the throttle slowly this does not happen. This is a Great Planes Eletrostik that came with motor & ESC already installed. LHS has given me a new motor and a new ESC, same problem. I thinking it must be something to do with the battery or connectors. Any ideas?!
Thanks...Robert
I have seen this before. It may be that you need to setup the esc to get the "timing " right.
Some esc's have a hard or soft setting. If you don't get it right you get the sort of problems you reported here.
cheshireflyer is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.10095 seconds with 14 queries