Turnigy 80-100 - Why so hot?

[mauimart]

I have been messing around with a cheapo 72V Hua Tong 15-FET controller to see how well it spins my Turnigy 80-100 outrunners. My thinking is to use it as a replacement of my Kelly if and when it blows. In any event I was spinning the 130Kv stock wound motor under no load to see what the max rpm of the Hua Tong was. It got it up to 7770 rpm before it lost sync (note at 1:40 in video that the current jumps to 10A right when rpm hits max), which works out to just over 54000 eRPM. Pretty good for a $37 controller. During the 3 to 4 minute test at 70V and 5A under no load, I was surprised to see the motor was quite hot, pushing 80 degrees C. I guess all of that 350W is going into heat... The controller did not get much above ambient during the test. The strange thing is that my rewound 80-100 does not get nearly that hot, even while under load on my bike. I think 50 degrees C is the most I got on that one under average power of 1000W for 10 minutes. It has internal halls placed at 120 degrees and was powered by the Kelly. Might the excess current draw and subsequent heat generation have something to do with the externals halls not being perfectly placed and hence providing poor timing? Anyone else seeing 5A no load current @ 70V for the 130kV motor?
over

[youtube]OL4XvbuKoYk[/youtube]

 

[Kurt]

The funny thing is I noticed my 80-100 getting reasonably hot during similar full rpm no load tests. The can of the motor defiantly wasn't 80c though. I could still hold my hand on it for a short period but it was still hot.

When the motor is in the bike and under riding conditions it never gets more than a little warm. Even when feeding it 2500w and climbing big hills. So I am not sure if it is just the airflow on the bike or something to do with friction and bearing heat from high RPM under no load. That big skirt bearing knocks out some heat at high RPM. If I had to pick one I would say its the air flow you get on the bike that's the biggest contributor to less heat.

I also think 70v is a lot for stock 130kv motor, I actually recorded mine at 144kv so would be over 10,000rpm at WOT. They start to sound a little stressed at this RPM.I feel they are a lot less stressed at around 5000rpm

By the way when I did continued to do stationary testing a ran a small desk fan on the motor and it never got more than warm.

[youtube]7TUqmZeMGzg[/youtube]

Kurt

 

[Thud]

From My experiance,
you are running into non optimal timing for the rpm's. if you can adjust your halls on the fly you'll be able to get the no-load into the 4.5 amp range at max rpms.

The XieChange controllers do a bit of timing advance...but i have a green board no-name controller that acts exactly as the one in your video.

Another word of caution...I have never been able to get an external sensor mount working satifactorly on an 80mm motor on a bicycle. On the bench yes, on the bike no.

you will see some dramatic heating on these motors spinning above 9k rpms. front bearing or not. Iron losses start to kick in prety strong at that speed.

Going internal has yeilded much more consistancy from testing to application.
Good Luck.
T

 

[Burtie]

The XieChange controllers do a bit of timing advance...
T

This is a common myth on this forum.

The XieChang controllers (116 processor), that I have played with, do not have any ability to advance the timing.
They are not complex enough to pre-empt the hall sensor signals.
They simply change the commutation state, when the hall signals change.

You can see this is the case, if you 'scope the hall and phase signals together.

There is of course a small, unavoidable processing delay (latency) between seeing the hall signal change, and switching the power to the windings. The HuaTong controller may have a bigger latency than the XieChang, and this would account for its inferior high rpm performance.

The latency would have the effect of retarding the timing, increasingly, as the rpm rises.


Everything else you say here Thud, I completely agree with

Burtie

 

[Thud]

that makes perfect sence Burtie. (i would never question a man with a scope! )

I am a bit curiouse about the 120% throttle option we have in the parameter designer flashing software....I allways assumed (dangerous i know) it was a timing tweek.
thanks for the straight dope.

 

[Burtie]

I am a bit curiouse about the 120% throttle option we have in the parameter designer flashing software....I allways assumed (dangerous i know) it was a timing tweek.

The 120% throttle option does not change the timing. It just removes the small amount of PWM that is normally still there at WOT. This is what produces the increase in power that people experience.

The controller normally has some pwm at WOT in an attempt to prevent destructive phase currents from building. With pwm present, the phase currents are kept in check by the motors inductance.

Edit:
Just thought, -Another reason to always have pwm present, is to ensure the bootstrap for the FET drivers stays charged, even when commutation is slow or stalled.

When you use the 120% throttle option to remove WOT pwm, you loose this safeguard.

Burtie

 

[Thud]

Thanks Burtie,
That is valuable info for us spinning rc motors with these. (i need to re-flash some controllers tonight lOL)

 

[recumpence]

Hopefully this does not muddy the waters, but, I know with sensorless setups, I have seen motor heat when running without a load. I assumed this was related to the sensorless timing varying itself incorrectly with no load. Is there anything related to that going on here?

Sorry if this takes the subject off topic...... :|

Matt

 

[mauimart]

I was running the motor a bit more at high speed ( >5000 rpm) and one of the bearings completely failed. It's quite obvious that most of the heat at no load is coming from the sub-standard bearings. Luckily I had a spare (used bearing from my other 80-100) and put that in. Still getting hot at high rpm. In the mean time I ordered a whole set of higher quality replacement bearings that I will install once they arrive.

I did some additional testing with the same motor/controller setup, this time under load. I was turning a 30x20 prop with the setup for a few minutes at WOT throttle and it seems like the controller is limited to about 35A continuous. On my 18s pack this translates to a bit over 2kW. At roughly 2500 rpm the motor was just warm. It's getting a bit of airflow in the pusher configuration but not as much as it would had the prop been pulling. In any event the motor is not nearly as hot when pushing over 2000W at low rpm vs. 350W at high rmp - this outcome again points to the crap bearings generating heat at high rpm.

I think I am going to open the controller and decrease the resistance of the current shunt and see if I can get a little more current out of this cheapo controller.

When I replace the bearings I also want to install internal halls at 120 deg. Does it matter between which stator teeth I install them, being the stock delta wind?

(note @ 1:19 in video my 20A fuse glowing and burning out - forgot to put a bigger one in)
over

[youtube]O3z9SCxTczA[/youtube]

 

[Burtie]

I also want to install internal halls at 120 deg. Does it matter between which stator teeth I install them, being the stock delta wind?

This might be helpful:

http://endless-sphere.com/forums/viewtopic.php?f=30&t=15686&hilit=ryan&start=210#p358841

http://endless-sphere.com/forums/viewtopic.php?f=28&t=26005&p=386328&hilit=burtie#p386088

 

[AussieJester]

Yes it does matter what teeth they are
Fitted between, several positions will work only
One will be correct though, the one that draws least current
Its a case of trial and error to find the correct
Position.

KiM

 

[Kin]

Does anyone run this motor (or similar ones) at lower voltages?

The turnigy 80-100 130kv seems to be one of the few (<$200) motors on HK that have a low enough Kv to run a low-rpm (<5k) system. Everything else seems to have 200+kv and even at only 12 that's going to be 8k loaded 10k unloaded rpm. Sorry if I'm missing something.


I don't really need more than 900w peak from the motor. Which at 6s nominal would be 40 amps and at 5s would be <50amps.

Is it simply that people are trying to get more like >3kw from the motors, and so they cant possibly use such high current?

This thread is encouraging me, because it seems that while I might loose some current from having a higher current ESC, I might also save some loses in the bearings. Hopefully this isn't too off topic.

 

[Bazaki]

I was running the motor a bit more at high speed ( >5000 rpm) and one of the bearings completely failed. It's quite obvious that most of the heat at no load is coming from the sub-standard bearings. Luckily I had a spare (used bearing from my other 80-100) and put that in. Still getting hot at high rpm. In the mean time I ordered a whole set of higher quality replacement bearings that I will install once they arrive.

I did some additional testing with the same motor/controller setup, this time under load. I was turning a 30x20 prop with the setup for a few minutes at WOT throttle and it seems like the controller is limited to about 35A continuous. On my 18s pack this translates to a bit over 2kW. At roughly 2500 rpm the motor was just warm. It's getting a bit of airflow in the pusher configuration but not as much as it would had the prop been pulling. In any event the motor is not nearly as hot when pushing over 2000W at low rpm vs. 350W at high rmp - this outcome again points to the crap bearings generating heat at high rpm.

I think I am going to open the controller and decrease the resistance of the current shunt and see if I can get a little more current out of this cheapo controller.

When I replace the bearings I also want to install internal halls at 120 deg. Does it matter between which stator teeth I install them, being the stock delta wind?

(note @ 1:19 in video my 20A fuse glowing and burning out - forgot to put a bigger one in)
over

[youtube]O3z9SCxTczA[/youtube]

Thanks for sharing, Maybe i am missing something but how do you get 2500 rpms at a 130kv motor at 70 volt just half throttle or is it because of the load, ?

 

[mauimart]

Thanks for sharing, Maybe i am missing something but how do you get 2500 rpms at a 130kv motor at 70 volt just half throttle or is it because of the load, ?

The lower rpm stems from the fact that there is a load and even though the thottle is in the max position the controller is limiting the current.