TREX 500 esc thermal shutdown

[mikewebb]

Hey guys and gals,

Was out hovering the TREX 500 the other day, when at about 15 ft, nose into a steady wind of 10 kts, the motor quit. Did my best impression of an auto, and got her down undamaged. With heart racing and the collective still full up, she powered up again a few seconds later (full power) and started to spin on the ground. Throttle hold quickly took care of that, and I still have an intact helo.

I surmised the problem was an ESC overheat, so I moved the ESC from beneath the battery tray to the side frame, exposed to the fan effect of the main gear. Also, I changed the battery protection in the Align ESC from disabled (option 3) to low protection (option 2) and went flying. No more cutoff, and after 8 minutes of hover everything is cool.

I suspect that when operating the ESC in the battery protection disabled mode (option 3), the thermal protection feature reverts to an instant cutoff, where as with any other battery protection mode enabled, you would get a power reduction for an overheat condition vice an abrupt cutoff.

My power setup:

5S Kong 3200 bat
14T pinion
throttle curve in norm: 0-65-85-inh-100 (DX-7)

Any thoughts or comments would be greatly appreciated.

[mewsikman]

Were you able to get the temp of the esc when this happened???

[mikewebb]

No I didn't. The cooling fins felt hot to the touch though.

[mewsikman]

Strange..... Had you run any packs before that or was that the first pack of the day???

[mk1spitfire]

good save

[PTFlyer]

are you using the built in bec or a seperate one?

[mikewebb]

First flight of the day, and am using the built in BEC.

[mewsikman]

Really weird..... Maybe try reprogramming ur esc, might fix it..... If not then you might have a bad esc...

[Hangarace]

2.4 and the stock esc? I have had it shut down but lost all power to electronics till it reset. Are you sure you had ail/elev control?

[mikewebb]

Let me be clear here. I have, until recently, been flying with the "battery protection" feature of the Align RCM-BL60G esc disabled, as selected in the programming mode 3 (high).

It seems that by disabling the battery protection that it affects the overtemperature protection as well, ie abrupt cutoff in the event of a ESC overtemp. I have recently reprogrammed the ESC battery protection function to "mid cutoff voltage protection", which specifies a reduction in power to the motor when the battery voltage, under load, reaches 3.o v/cell. Of course I never intentionally take the battery that low during flight, as evidenced by the charge remaining postflight, however I am not certain of the instantaneous voltage under load of the battery at any time. I believe the issue is how the motor cutoff function behaves when the battery protection function is disabled. If anyone has knowledge of how the cutoff function really works, that is the answer I'm looking for. Since I have enabled the battery protection function, (level 2), I have had no more problems.

Thanks in advance for your indulgence.

[cudaboy_71]

FWIW, this is pretty much how the tail static issue presented itself to me. you have read the sticky at the top of the forum, right?

i did every mod in the book, including but not limited to: external BEC, 75amp ESC. but, nothing stopped the motor from cutting out like that until i grounded the boom.

[mikewebb]

thanks cudaboy,
that's an issue that i'm looking into.

michael

[psindrup]

First flight of the day, and am using the built in BEC.

I am no expert on this, but one flight should not cause the ESC/BEC to overheat.

I can fly 6s 3300mAh packs back to back without any hearing issues at all.

An (un)qualified guess could be that your programming/setup of the ESC was somehow f..... up, and reprogramming it did the trick.

Peter