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Baffled by overheating ESC

Old 08-22-2012, 02:32 PM
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solentlife
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Default Baffled by overheating ESC

Depron F16 .. (Tomhe design)

2200kv motor with APC 8x6 prop (designed for 7x6 up to 9x5 prop ), 2 x 3S 800mAh 20C Lipos in parellel, 35A Mystery ESC with 43cm long extension leads to motor - 0.8mm solid copper cables, standard length battery leads ESC to LiPo's.

First test - I could sense something was getting warm. Checked and the ESC was HOT.

I connected up wattmeter and opened her up again. 15.9A, 10.78V .... approx 160W were readings. ESC was HOT ... motor was near hot ... so what's wrong ?

ESC is well within range ... but why the motor getting hot as well ... it all spins up freely ... if the motor was dragging - the amps would shoot up higher .. but they are where I expected.

Plenty of thrust to fly - but don't want to when ESC is running so hot ...

Nigel
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Old 08-22-2012, 02:45 PM
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dahawk
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Very strange indeed. I'm also running 2200kv motors on my "prop in the slot" jets but have never used a prop bigger than a 6x4e APC or MAS. I'm using mainly 30 & 40Amp esc's. You would think you would see a spike in amp draw with this bigger prop on a low torque, high rpm motor.

I did have a stock esc in my JPowers AT-6 Texan( same esc as 50mm Skyangel) get very hot. But that was an exception I think.
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Old 08-22-2012, 03:57 PM
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flydiver
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You should be seeing MUCH higher readings. IMO that prop is (way) too large for that motor. Something more in the 6x4 range is more appropriate.
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Old 08-22-2012, 04:18 PM
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What is the behaviour of an overheating esc?

Can overheating the esc cause it to fail cutting power to motor and rx? After it cools down would it go back to working correctly?
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Old 08-22-2012, 04:18 PM
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pmullen503
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Originally Posted by solentlife View Post
Depron F16 .. (Tomhe design)

2200kv motor with APC 8x6 prop (designed for 7x6 up to 9x5 prop ), 2 x 3S 800mAh 20C Lipos in parellel, 35A Mystery ESC with 43cm long extension leads to motor - 0.8mm solid copper cables, standard length battery leads ESC to LiPo's.

First test - I could sense something was getting warm. Checked and the ESC was HOT.

I connected up wattmeter and opened her up again. 15.9A, 10.78V .... approx 160W were readings. ESC was HOT ... motor was near hot ... so what's wrong ?

ESC is well within range ... but why the motor getting hot as well ... it all spins up freely ... if the motor was dragging - the amps would shoot up higher .. but they are where I expected.

Plenty of thrust to fly - but don't want to when ESC is running so hot ...

Nigel
I think you are using too much prop for 2200kV on 3S. Try a 6x4. I can't explain the low amp reading. There could be a timing issue on your ESC. If you can, try some different settings. The huge voltage drop is suspicious. At 16A you are running at only 10c. Unless your batteries are shot, they should be running closer to 12V right off charger. You didn't say if the battery was running hot but that level of voltage drop, if correct, would indicate a severely stressed battery.

I've run a Suppo 2212/6 2200kV for a couple years on my Polaris. I use a MA 6x4 with a 40A ESC that got hot enough to shut down until I added an extra heatsink. It pulled only 25A. Changing the timing helped but it still ran hot. At WOT a fresh 1600 mAh battery gives around 12V via telemetry. I figure it's time to land when the battery can't hold 10.5V under load.

The heat may be from an over stressed onboard linear BEC. You could try hooking everything up with a separate battery or UBEC and disconnect the red wire from your ESC.

Heat is wasted energy not available to fly the plane.
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Old 08-22-2012, 04:20 PM
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flydiver
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Depends on the ESC. Some simply fail outright, some shut down, some slow down. The 'better' ones reset after cooling down.
For a Mystery ESC.....well, it's a mystery to me. They may or may not be a decent unit as they have changed their origins over time. They do not make ESC, they rebrand them.
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Old 08-22-2012, 04:22 PM
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pmullen503
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Originally Posted by WayfaringDreamer View Post
What is the behaviour of an overheating esc?

Can overheating the esc cause it to fail cutting power to motor and rx? After it cools down would it go back to working correctly?
Many ESC's have thermal protection and will shut down. That includes the BEC resulting in loss of control.
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Old 08-22-2012, 04:26 PM
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Thanks for the responses. I need to delve deeper into my model (hacker x40).
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Old 08-22-2012, 04:38 PM
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I suppose if he's not using a lot of servos on the profile F-16, the Linear Bec would work just fine. I have over 100 flights on my Dollar Tree F-22(elevons only) using a Grayson V2/30 amp esc with linear bec, 6x4 MAS prop. It's like the Energiizer Bunny, just keeps on going ! I do know that the these low torgue 2200's will get bogged down in a hurry with a prop much larger than a 6 x 4. I tried it on a converted(bashed) Air Hog kids glider. Went with a 7x5 apc and things started getting warm from the get-go.

Maybe something's a miss in the readings?
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Old 08-22-2012, 04:40 PM
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Originally Posted by solentlife View Post
Depron F16 .. (Tomhe design)

2200kv motor with APC 8x6 prop (designed for 7x6 up to 9x5 prop ), 2 x 3S 800mAh 20C Lipos in parellel, 35A Mystery ESC with 43cm long extension leads to motor - 0.8mm solid copper cables, standard length battery leads ESC to LiPo's.

First test - I could sense something was getting warm. Checked and the ESC was HOT.

I connected up wattmeter and opened her up again. 15.9A, 10.78V .... approx 160W were readings. ESC was HOT ... motor was near hot ... so what's wrong ?

ESC is well within range ... but why the motor getting hot as well ... it all spins up freely ... if the motor was dragging - the amps would shoot up higher .. but they are where I expected.

Plenty of thrust to fly - but don't want to when ESC is running so hot ...

Nigel
I've run across one or two of those very low cost wattmeters that were way the heck off in their calibration. Like a factor of two. Have you tried a different wattmeter???

My main unit to measure current is the Sears Craftsman #82369 AC AND DC clamp on ammeter. This unit allows measuring current without having to put the meter in series with the battery and ESC. Simply clamp its jaws around one battery lead. Not cheap at some $60, but IMHO worth every penny. This meter can measure the usual volts, ohms, and so on, along with frequency, thermocouple temperature and a lot of other stuff.

FYI, most clamp on ammeters are AC only, not useful for our electric models.

(Hey, its on sale with free shipping until this Friday AM! http://www.sears.com/craftsman-digit...1&blockType=G1)
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Old 08-22-2012, 06:48 PM
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Nigel,

I went back to your F-16 thread, but could not determine exactly which motor you are using on it. But if it is a 2200kv motor like the 2212-6, then you are definitely way overpropping it and that is what's causing your ESC to drop out as you're pushing too many amps through it.

If you have the 2212-6 motor, the largest prop it can take on 3S is the 6X4E. The motor and ESC do get warm, but you should never have any issues with that setup and a 30A ESC.

You may be able to use a larger prop, but only if you go down to 2S. I've been flying these pusher jets for years now, and the perfect combo is the 2212-6 2200kv, 30A ESC, APC 6X4E prop and a 3S 1300-2200 lipo.
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Old 08-22-2012, 08:06 PM
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solentlife
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The motor has sat on the shelf for ages and only got used for testing a Parkjet ... then she ran a 5x5 ...

I made error - it's 1800kv ... not 2200 ....

Here's the same motor but with a label on it !! Mine lost its label long ago !

http://www.ebay.co.uk/itm/New-2208-1...item3f0ea6cbd4

As you see .. it's listed as 9x5 on 3cells.

I'm reluctant to go down to a 6x4 as I doubled up the fuselage spine - was very flexi ... and I have 4 servos on it ...
What I may do is crop an old 8x6 back and see what happens.

I've linked tail and aileron servo on each side so I have ailervators ...

Nigel
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Old 08-22-2012, 08:44 PM
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pmullen503
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I have the Suppo version of that motor (at least it looks identical) and an APC 7x4 was the best match (for max thrust, high speed not an issue) on 3S. I have it on a powered glider and so it runs for only 20-30 sec at a time. Draws about 12A static. It's only rated for 16A for 60 sec.

Manufacturers' prop ratings can be very unrealistic. A 9x5" prop is better suited to 1000 -1100 Kv on 3S for a small motor. I also have the 1200Kv version of that motor and 9x5 was definitely too much for that motor. 8x4 was a good match.

Take a took at Drive Calculator at http://www.drivecalc.de/.

I've found it very reliable and it's free!
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Old 08-22-2012, 09:21 PM
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Yeah, even the 2212-6 has a prop chart that says 7x5 is OK on 3S, but that prop will burn up the motor and/or ESC for sure.

EDIT - Oops, my bad. 7x5 is listed as 2S only, as it should be. And 5x5 on 3S.
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Old 08-22-2012, 10:23 PM
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JetPlaneFlyer
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Just add my voice to those saying you are massively over-propped. The eBay listing is wrong, something like a 7x4 would be about the biggest you could go on a 40g 1800kv motor on 3s.
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Old 08-22-2012, 10:41 PM
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Oops, wrong person. Ignore the rambling old man.
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Old 08-23-2012, 12:36 PM
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Originally Posted by pmullen503 View Post
Many ESC's have thermal protection and will shut down. That includes the BEC resulting in loss of control.
That would be too drastic: ESC saved but plane total loss.
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Old 08-23-2012, 01:10 PM
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Originally Posted by ron_van_sommeren View Post
That would be too drastic: ESC saved but plane total loss.
That's why I now use a separate switching BEC on everything but a few foamies.

I wonder how many crashes caused by "receiver problems" where really ESC thermal shut downs.
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Old 08-23-2012, 02:20 PM
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Originally Posted by pmullen503 View Post
That's why I now use a separate switching BEC on everything but a few foamies.

I wonder how many crashes caused by "receiver problems" where really ESC thermal shut downs.

I with you on this.
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Old 08-23-2012, 03:33 PM
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Originally Posted by pmullen503 View Post
Many ESC's have thermal protection and will shut down. That includes the BEC resulting in loss of control.
You sure about that?
My understanding is built in BEC's are in principal just like stand alone BEC's, only they are integrated into the same PCB as the ESC. It would be an unusual 'safety' feature that was engineered deliberatly to shut down the receiver in flight when it was working perfectly ok?

Some ESC's do have thermal shutdown but I understood that shutdown of the 'power circuit' didnt directly effect the BEC. In fact you can demonstrate something similar by powering up the model with the throttle in the half open position. The power circuit remains shut down but the BEC works as normal. The BEC may have it's own thermal shutdown function but it's separate from the main ESC power circuit (I think).. Of course a BEC shutdown does take everthing down also if the ESC goes up in flames then the BEC will almost certainly fail too.
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Old 08-23-2012, 04:29 PM
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Jetplaneflyer is correct as I am led to believe ...

There are no shutdown BEC ESC's in general over counter ... it's an expensive option that no chinese factory will install !

I have had power shutdown but BEC still cont's on. In fact even go to LVC and BEC still works till that falls so low it cannot power the Rx sufficiently.

Shutdowns are purely a motor LVC issue ...... and a Rx only drops out when voltage sags below it's operating limits and servos are not receiving enough power to turn arms ...

What I find interesting is comparing old days to now ... we never worried about putting 4.8v NiCD / NiMH packs in planes for Rx / Servo power. Big and small models. On big - we fitted back-up pack via a sensor that switched to back-up if main pack dropped below a set voltage level. We never talked about brownouts ... we just said pack failed. Now there seems to be a new dimension and all sorts of claims etc. that as an old school flyer I find difficult to agree with some.
The voltage levels that Rx's drop out at - even those of 'higher volts' .. are below what is reasonable to operate a servo ...

My 2 cents worth ....

Nigel
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Old 08-23-2012, 04:29 PM
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pmullen503
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Originally Posted by JetPlaneFlyer View Post
You sure about that?
It is absolutely the case on cheap ESC's with linear BECs.

After totaling my first Polaris to a "loss of control", I built a new one and reproduced the problem on the bench with a Suppo 40A ESC. Thermal shutdown kills everything. I now run it with an extra heat sink exposed to the outside airflow and a separate BEC.

Tricky thing with Spektrum is that failsafe zero's the throttle on loss of signal so thermal shutdown looks exactly like brownout. When you retrieve the crashed plane everything works normally so it looks like a loss of signal caused the crash.

Separate, switching BECs are cheap insurance.

I lost a plane a few years ago due to onboard BEC failure. I was flying in the dead of winter, maybe 10 degrees F. I experienced loss of control AND instant full throttle right into the frozen ground. I now realize that (4) 9g servos can pull over 3A if they are cold enough. Interestingly, while the BEC is burnt out, the ESC still works. I use it to power a small hotwire bow.
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Old 08-23-2012, 04:53 PM
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Originally Posted by pmullen503 View Post
..........Interestingly, while the BEC is burnt out, the ESC still works. I use it to power a small hotwire bow.
Works other way as well ... I use an old ESC that doesn't work anymore to provide bench BEC .....

I've had all sorts of crashes .......... bizarre, obvious (well initially seemed so) .. all kinds of models etc. The only ones I can then say with any degreee of confidence on reason are those that have been video'd. They happen quickly, you often are shocked and reaction is too late or not correct ... then we all fall into the trap of human nature and find a cuplrit for the crash.

My first 50mm EDF ... she flew month after month fine ... then suddenly no matter what I did - she would crash. Discussions with other flyers who witnessed ... ESC failure ... BEC failure ... Servo failure ... you name it - we had all mentioned ... I changed ESC, I fitted UBEC, I changed servos, Rx, even second radio system .......... I did everything ... still she crashed. To this day - I still don't know why ........ and I've been in this game for more than 40yrs.



Nigel
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Old 08-23-2012, 06:18 PM
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I know..........
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