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Prop spins when receiver is turned off?

Old 12-30-2011, 04:07 AM
  #1  
craigrs84
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Default Prop spins when receiver is turned off?

I just bought a new Exceed RC 480 Engine and an Exceed RC 40A ESC.

I hooked everything up and it is working well, except occasionally when I turn off the transmitter (with the throttle turned off), the motor will start spinning moderately fast for a few seconds and then stop again. I'm not positive but it looks like its spinning backwards.

Anyone ever experience this behavior before? Not sure how to correct it.

Last edited by craigrs84; 12-30-2011 at 03:31 PM.
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Old 12-30-2011, 04:30 AM
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NJSwede
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Originally Posted by craigrs84 View Post
I just bought a new Exceed RC 480 Engine and an Exceed RC 40A ESC.

I hooked everything up and it is working well, except occasionally when I turn off the receiver (with the throttle turned off), the motor will start spinning moderately fast for a few seconds and then stop again. I'm not positive but it looks like its spinning backwards.

Anyone ever experience this behavior before? Not sure how to correct it.
Why would you want to turn the receiver off with the esc on? In the absence of a meaningful signal from the receiver, the esc probably picks up some noise it mistakes for throttle input. I'd just make sure the rx is always on when the power system is on and forget about it.
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Old 12-30-2011, 07:46 AM
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CHELLIE
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Originally Posted by craigrs84 View Post
I just bought a new Exceed RC 480 Engine and an Exceed RC 40A ESC.

I hooked everything up and it is working well, except occasionally when I turn off the receiver (with the throttle turned off), the motor will start spinning moderately fast for a few seconds and then stop again. I'm not positive but it looks like its spinning backwards.

Anyone ever experience this behavior before? Not sure how to correct it.
Never just turn off the receiver, always disconnect the Battery power from the aircraft, The transmitter is always the first thing to turn on and the last thing to Be turned off, to be on the safe side, by turning off just the receiver, you may have messed up the ESC throttle setting end points, here is how to reset the throttle end points.

http://www.wattflyer.com/forums/show...tle+end+points
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Old 12-30-2011, 08:28 AM
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JetPlaneFlyer
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As said by the others..
Rule #1: NEVER turn the Tx off with the model still powered up. Turn on the Tx first and turn it off last.
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Old 12-30-2011, 08:43 AM
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Larry3215
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I agree with everyone else but will add one more point.

A quality esc will shut the motor off when it looses signal from the rx. Your esc isnt doing that.

Its either dangerously low quality or its broken.
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Old 12-30-2011, 03:30 PM
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craigrs84
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I just realized I made a mistake on the original post. It happens when I turn off my transmitter NOT my receiver. Sorry for confusion. Although I think you guys probably knew what I meant.

Yea my ESC is probably cheap, I didn't buy name brand. I will just start turning transmitter off last.

Thanks for help.
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Old 12-30-2011, 03:36 PM
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Originally Posted by craigrs84 View Post
I just realized I made a mistake on the original post. It happens when I turn off my transmitter NOT my receiver. Sorry for confusion. Although I think you guys probably knew what I meant.

Yea my ESC is probably cheap, I didn't buy name brand. I will just start turning transmitter off last.

Thanks for help.
Short answer: Don't do that! You should never turn the tx off when the plane is powered up. If you have a 72MHz system, there's a very good chance you pick up random static or a signal from some distant station that your transmitter would have otherwise masked. With a 2.4GHz system, the chance of picking up static is a lot smaller, but it's still a good practice to keep the tx on whenever your plane is powered up.

Out of curiosity, what radio do you have? 72 or 2.4?
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Old 12-30-2011, 04:17 PM
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Smile Power Switch

Following the transmitter on first and last off train of thought, are there any switches available which could be put in line with the 3s or 4s lipo batteries? I saw a safety plug on line which is new on the market but I would rather have a switch. It would have to be small enough and light enough to mount on the aircraft. But, it must be rated for the voltage and
current levels it would operate.
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Old 12-30-2011, 04:56 PM
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Originally Posted by Motor Glider View Post
Following the transmitter on first and last off train of thought, are there any switches available which could be put in line with the 3s or 4s lipo batteries? I saw a safety plug on line which is new on the market but I would rather have a switch. It would have to be small enough and light enough to mount on the aircraft. But, it must be rated for the voltage and
current levels it would operate.
Something like this would work for smaller planes:

http://www.radioshack.com/product/in...ductId=3125353

You could go two-pole if you wanted to be really fancy, but this one would do the job of cutting power to the plane just fine.
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Old 12-30-2011, 05:44 PM
  #10  
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Thanks NJSWEDE! This switch is even in stock in my local radio shack and inexpensive. I appreciate all the help I can get.
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Old 12-30-2011, 06:02 PM
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No problem. Your local auto part store probably has something similar. Just make sure it's rated for enough amps and you'll be just fine.
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Old 12-30-2011, 08:18 PM
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Yea I am using 72 mhz
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Old 12-31-2011, 12:27 AM
  #13  
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Default Remember this.

The switch is ONLY switching the voltage ON & OFF when NO current is running. So you can go with a lot lower amp. rated switch. 30 amps max ? a 10 amp switch will work fine.
I have them on several GWS planes. The Corsair has the switch on the belly. Short grass landings pushes the toggle switch back, Which is OFF.
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Old 12-31-2011, 12:43 AM
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Originally Posted by cyclops2 View Post
The switch is ONLY switching the voltage ON & OFF when NO current is running. So you can go with a lot lower amp. rated switch. 30 amps max ? a 10 amp switch will work fine.
I have them on several GWS planes. The Corsair has the switch on the belly. Short grass landings pushes the toggle switch back, Which is OFF.
Not sure I agree with that. The current that flows through the switch when it's switched on is just as important (if not more important) than the initial current. The reason is that a switch rated for a lower current (less amps) is going to have thinner internal conductors than a high-amp switch. Thinner conductors mean higher resistance, more power lost as heat and less metal to handle the heat, which could lead to failure. I would definitely not push my luck getting a $2 switch instead of a $5 one if it could cost me a complete power loss and a lost model.

Let's have our resident expert on switches (you know who you are) chime in on the subject!
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Old 12-31-2011, 12:44 AM
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Originally Posted by craigrs84 View Post
Yea I am using 72 mhz
Well, then the switched off transmitter is DEFINITELY the problem. A 72MHz receiver without a signal picks up all kinds of static and can send out pretty much any signals on the servo connectors, so BEWARE!

The good news is that your ESC is working just fine!
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Old 12-31-2011, 12:47 AM
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I thought I was a expert on switching capacities of inductive loads. & current carrying capacities of resistive & reactive loads. In the real world.
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Old 12-31-2011, 12:58 AM
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Originally Posted by cyclops2 View Post
I thought I was a expert on switching capacities of inductive loads. & current carrying capacities of resistive & reactive loads. In the real world.
Maybe you are! In that case I bow down to your superior knowledge!

No, but seriously, you don't think you'd have a problem with heat in a switch carrying three times its rated max current? Knowing how warm the battery leads can after some aggressive flying in some of my models, I'd be worried about heat in a switch...

I'm a digital electronics and software guy, so I know very little about anything higher than 5V and a few amps...
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Old 12-31-2011, 01:26 AM
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Originally Posted by NJSwede View Post
Something like this would work for smaller planes:

http://www.radioshack.com/product/in...ductId=3125353

You could go two-pole if you wanted to be really fancy, but this one would do the job of cutting power to the plane just fine.
That's a real surprise! Someone actually makes a 50 Ampere toggle switch! As for the 12 Volt rating, that should not be a real problem, since the motor is likely to be off when the toggle switch is flipped. So, the switch is being flipped with no current through the contacts.

I'm just wondering what kind of contacts this switch has internally. Normally the internal contacts of a 50 amp relay are pretty big.

I'd be a little reluctant to try pushing 50 Amperes through a 10 Amp toggle switch though. I've disassembled a LOT of toggle switches, relays and similar to determine cause of failure over the past (many) years. The typical contacts inside a 10 Amp toggle switch are rather light duty, and will heat up very rapidly at 5X rated current. The heat build up is proportional to the current squared, so 5X is 25 times the watts lost in the contact material. It's going to get hot. What can happen is the overheated switch contacts can melt the plastic shell of the switch. When this occurs, anything can happen, from the switch going intermittent, to stuck closed, to stuck open. It can also severely overheat the contact springs inside, making them soft.
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Old 12-31-2011, 01:48 AM
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I agree with you, Denny. And I'd actually go a step farther and say I'd avoid the switch altogether. Switches are pretty delicate mechanical components and introduce a single point of failure in the power system. Plus, they steal away precious watts and amp hours.

What I've seen people do is to mount a deans plug or similar as a "jumper" on the outside of the fuse that can be pulled if the model needs to be powered down quickly. Simpler and less failure prone.

It would be interesting to see what you're doing in terms of "kill switch" on your multi-kW models, Denny!
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Old 12-31-2011, 05:33 AM
  #20  
kyleservicetech
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Originally Posted by NJSwede View Post
I agree with you, Denny. And I'd actually go a step farther and say I'd avoid the switch altogether. Switches are pretty delicate mechanical components and introduce a single point of failure in the power system. Plus, they steal away precious watts and amp hours.

What I've seen people do is to mount a deans plug or similar as a "jumper" on the outside of the fuse that can be pulled if the model needs to be powered down quickly. Simpler and less failure prone.

It would be interesting to see what you're doing in terms of "kill switch" on your multi-kW models, Denny!
You're right, I don't use toggle switches for power control on my models. Had to many field failures of toggle switches in the controls I repaired during many years at work. In fact, it was standard practice at work to use double pole switches with parallel contacts in critical circuits for added reliability.

And, unexpected start ups of a motor that can turn a 19X12 APC-E meat slicer unexpectely at 7000 RPM is something that absolutely must be avoided.

As for multi-KW models, take a look:
http://www.wattflyer.com/forums/showthread.php?t=65052

The Anderson Powerpole connectors are set up to allow running the motor with a 12S2P A123 pack. Then charging the same battery pack as a 6S4P pack with a Cellpro Powerlab 8 charger, set to 20 Amps charge rate.

As for the wiring, take a look at the attached JPG. The power connection between the pair of 6S2P A123 packs consists of four Anderson Power Pole jumpers that plug in, one at a time to power the ESC and motor. It was used all last year, with no issues.

The receiver power is a Castle Creations 10 Amp uBEC connected to the 6S2P battery tap, plus a two cell 2300 Mah A123 battery pack as a receiver backup supply. That's what you do when you've got $1000 flying in the air!
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Old 12-31-2011, 01:32 PM
  #21  
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Swede

I deal with NEMA ratings. Or at least a rated capacity. The safety factor is far higher for switches when they are derated for intermittant model airplane SPORT flying.

Hovering at 80% for several minutes.....WoW unlimited vertical climbs....underpowered & oversized props....All of those conditions are NOT GOOD sizing.

If you are NORMALLY pulling 30 C to + 50 C out of a battery of 1000mahr. or larger. STAY AWAY FROM switches !!!!!!!!!!!!!!!!!!!!!

Use the KEYED plugs & receptacles. I use the XT-60 ones on the Nanotech 2.2 ahr packs. Cheap, male & female, high current, solders VERY EASILY every body sells them cheap.

Remember. You ONLY need the setup I am posting in ...EITHER ... lead. I Epoxy the battery MALE SOCKET in the side of the plane. The REMOVABLE jumper must be the same type as on the end of the battery leads.
That way you should NOT be able to cause a SHORT CIRCUIT to the battery accidently.
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Last edited by cyclops2; 12-31-2011 at 02:03 PM.
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Old 01-02-2012, 03:52 PM
  #22  
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Just wanted to confirm all your suspicions.

I am using a 72mhz radio system and the problem was interference and was NOT caused by a faulty ESC. I removed my ESC completely and just plugged in a battery and a couple servos and the servos went crazy too. The higher I raised the receiver antenna wire the worse the problem became.

I was surprised because I had never experienced this behavior before with any of my other radio systems which are also 72mhz. However, this is a new receiver and transmitter and it uses a different channel than my other radio systems. It seems there is some severe environmental interference on this channel but not on the other channels, which is why I never noticed it before. Glad I figured this out sooner rather than later.

Thanks for your help.
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Old 01-02-2012, 07:56 PM
  #23  
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Do not test any RC gear indoors where there are Air Conditioning pipes in the floors, wall or ceiling. They....DO... cause reflected / delayed ghost signals to bounce all over the area.

My AC pipes HAVE caused my 72 mhz stuff to run erraticaly or jam a servo. Flourscent lightbulbs can do the same thing in a BIG steel garage.

Same equipment 100' away from steel building runs perfect.

When my electric furnace clicks in each 5,500 heating element. TWITCH...TWITCH...TWITCH...TWITCH. I am 8' away from the furnace.
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Old 01-03-2012, 07:29 AM
  #24  
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Hi Most 72 Mhz Receivers that work well with Nitro, dont work for Darn with E Power, the older JR Receivers work great with nitro, but e power Drives them nuts Use 72 Mhz Berg receivers with E Power, Berg Receivers have triple ceramic Filters in them, and are the best with 72 Mhz and E power, Its all i use and never ever had a glitch with a berg receiver, and they dont cost more than other receiver too, they are about the same price, always use a berg crystal with a Berg Receiver, Hope that helps, Chellie

I Like the 4L receiver, on all mini receivers, use a piece of Scotch tape to hold the tiny crystal in place with or they will vibrate out.

http://www.thefind.com/family/browse-berg-receivers
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Old 01-03-2012, 12:48 PM
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I can add the Hitech & Bluebird to the list.

HOWEVER..........I do not exceed the 250 watt levels in any motor / EDF.
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