Overheating HDX500SE (burnt my fingers!)

[Heli Paramedic]

Hi All,

I've been having nothing but trouble with my HDX500SE. Can't seem to keep the damn thing cool. I started with the stock 890KV motor, 24T pinion and 60A ESC using a 4S 4000mAh lipo. After about 5 mins of hovering and gentle forward flight, the motor and ESC were so hot I burnt my fingers. Batteries were also a little too warm for my liking. I was told to upgrade the motor & ESC to the Sonix 1050KV motor with 19T pinion & Align 70A ESC.

After upgrading things are worse. After 2 mins of hovering you could fry an egg on the motor & ESC and now the battery is so hot it is starting to puff.

What could be causing my heli to heat up so much?

I've considered all of the obvious things. Gear mesh is perfect with no resistance in the main or tail rotor systems.

In normal mode pitch is minus 2 degrees @ low stick, 5 @ mid stick and 9 @ high stick.

Hovers just above half stick.

Normal throttle curve is 0, 85, 85, 85, 85.

Even tried a 3S setup using the 890KV motor & 24T pinion.

Any suggestions would be appreciated.

Thanks.

[Ticidytoc]

If you are practicing your hovering and forward flight then I would drop down at least 1 or 2 teeth on that pinion.

I would check all your connections, make sure everything is soldered properly and there are no motor wires shorting out. If you have a bad solder joint this will add resistance.

If this all checks out, then drop at least 1 or better yet 2 teeth on the pinion which should help things.

[Heli Paramedic]

Thanks for your reply Ticidytoc,

Did you mean drop 1 or 2 teeth on the 24T pinion & 890KV motor or the 19T pinion and the 1050KV motor?

As far as my solder joints they all look OK. The solder is shiny and smooth. Would a bad solder joint be enought to cause overheating of this magnitutde? I don't have a temp gun but the motor and ESC are too hot to touch fer even 1 or 2 seconds.

Is there any way to test resistance in a solder joint? perhaps using a multimeter? and if so what would be an acceptable value?

[Ticidytoc]

If your solder joints look good and it sounds like they do then try going down 1-2 teeth on both, but start with the 1050kv setup if thats what is in your heli now.

I wouldnt worry too much about checking for resistance issues quite yet. It more work than I think you will need to do. I helped someone out at my local field with this same problem, turns out to be a combination of 2 things, one was the motor was not up to task, which in your case the 1050kv z-20 is actually a good choice, and two the gearing on the heli was a bit aggressive, so in your case I believe its the gearing.

I would try a 17T on the 1050kv motor to start since your temps are as high as you describe.

[Rototerrier]

I am running A30-8XL with a 19T Revco, mine is warm to the touch but I can leave my fingers on it so it isn't super hot. I have noticed that it does get hotter when I just hover for 6 minutes, but nothing like you are indicating. I am extremely pleased with the A30 and would highly recommend it. I am sure there are others that might disagree, but since I haven't had a single problem with it in either hover or flight, I can't complain. Very little bog when using throttle curves and hardly no bogging when running fixed throttle, and runs very cool when not just hovering.

[Heli Paramedic]

Thanks,

I'll try a smaller pinion. My LHS which is unfortunately on the other side of the country and in a different time zone only stocks pinions down to 18 teeth.

After discussions with my LHS I am apparently the only customer he has had with such overheating problems. The owner of the shop says he has flown an HDX500 with the exact setup I am using & has had no overheating issues. He also was not able to offer any solutions to my problem. Therefor I must be doing something drastically wrong. Surely just hovering for a few minutes shouldn't be enough to cook a battery, motor & ESC. I don't think my lipos will be good for much longer as they are really starting to puff.

I read somewhere that gear ratios lower than 9:1 can result in excessive current draw. As my setup is 4.95:1 am I going to be stuck with overheating issues? Even if I drop a few teeth on my pinion I will not get anywhere near a 9:1 ratio. Should I just cut my losses and look for a heli that doesn't have this issue? Perhaps a Trex 500?

[booger]

So you Have bought 2 motors and they both get real hot.
Have you checked amp draw on the motors at the rpm you are using at 0 pitch. if the current draw is high on both motors. then most likely its not a motor issue but a drive train issue. something is binding
what is your head speed you are trying to run?

[Ecaf]

What ESC are you using? I found that going to high timing lowered my temps alot.


Something else to consider.

[Rototerrier]

Oh yea, I second that. I had to go to High Timing on my HobbyWing Pentium 60. I was eperiencing some weirdness at anything less. I tried to get away with lower to increase flight times, but the thing sputtered a couple times and did get a little hot.

[Ticidytoc]

What ESC are you using? I found that going to high timing lowered my temps alot.

Ahh good point, I'm not too familiar with the Align ESC, but I would look at this setting as well. Just not sure that timing is solely the problem with such drastic temp issues.

I wouldnt give up on the heli just yet, you already have an investment in the kit, there is a gearing change in the works here for the HDX and I am currently playing with the prototype gears as we speak.

[Heli Paramedic]

Thanks for your replies,

Yes I have 2 motors that are both getting very hot. The stock 890KV motor and the upgrade 1050KV motor. I am using the Align 75A ESC and the timing is set to high.

Booger - How can I test the Amp draw? Can this be done with a multimeter? What would be an acceptable current under these test conditions?

As far as head speed I'm not sure as I dont have a tach. I'm just going with whatever my gear ratio and throttle curve gives me.

I'm pretty sure the problem is not in my rotor system as it is silky smooth and takes forever to spool down. It feel it must be either the gearing or a problem with my electronics setup.

I really don't want to give up on this heli as it is a very nice machine, but I can't afford to be cooking batteries and motors after a few minutes of hovering.

[booger]

here is a graph of my hdx500 on 4 cells,scorpion 980 kv motor and 18 tooth pinion
you can see average amps is about 23 to 24 amps
and head speed is about 2300 rpm
if your just hovering by my calc the batts and gearing your running would put you close to 3000 headspeed so it is gonna be current hungry at those headspeeds
first thing I would try is dropping to an 18 to 20 tooth pinion and slow that headspeed way down. I believe your motor and batteries will be much happier.
and to measure your voltage and amps you at least need a watt meter
something like in this link
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLMV0&P=ML
but as you can see i have an eagletree and rpm sensor and it makes your setups rocksolid and you know if you got what you want or not
hope It helps
Rob

[Ticidytoc]

I would guess if the Align ESC will run the Z-power at low timing that is where I would keep it. This should help with temps, try all 3 settings to confirm. Lower your pinion after you check motor temps with temp gun. They are available here: http://www.helidirect.com/product_info.php?products_id=2336

I use this exact one which seems to work for as often as I need it. If your motor is running in the 200F range its not going to last long, you want to keep it in the 100F-150F max. Even if the windings are rated for more, which some motors are, the bearings seem to suffer when temps are in the 200F.

[juneebear]

Do you have a BEC installed with your ESC?