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Safe Operating Internal Temp


(Damon) #1

Hi, I was wondering what the safe operating temperature of the BlueROV is? I’m currently doing some bench testing and Ive noticed that the “critical Internal Temp” error has appeared. The rov has been used for probably a dozen dives without this error appearing. Internal temp (temperature 1) on the Qgroundcontrol dash is reading ~70C. The ambient temp is at 24C. Could the onboard temp sensor be broken? The pixhawk board definitely doesn’t feel that hot.


(Kaos) #2

The esc’s produce alot of heat and it cant dissipate thru the pressure vessel sides as well in air as compared to water. Take the vent plug out and work where there is a breeze to help with cooling. If you get the overheat warning, then shut down bench testing until it has cooled. Overheating electronics is not usually good for component efficiency or lifespan.


(Damon) #3

I just did some testing in water (18C) and the internal temp has still heating up to 71-72C within 5 mins of operation. Do you have any ideas about what could be causing this? I know it could probably be a number of things but everything else seems to be functioning as it didn’t previously except now the internal temp is up considerably. Any help would be much appreciated!


(Damon) #4

Ive narrow it down and the issue seems to be something to do with the voltage regulators. When I UNPLUG the regulator from the Pixhawk the temperature immediately starts to DROP again, when i plug it back in it shoots back up again. I tried plugging the regulator from the raspberry pi into the pixhawk and I get the same result. Both regulators are outputting 5.2V. Are both the regulators defective or is there some problem with the pixhawk maybe?


(Anthony White) #5

Hi Damon -
Under most testing I’ve done, in water only slightly cooler than your situation, internal temperature reported by QGC hangs out in the 50C range. 70+ C is definitely getting toasty!

What other voltages are connected to the pixhawk? Verify that none of your ESCs have a 5v line connected - only the camera servo is powered from the 5V supplied by a regulator plugged into the pixhawk.

I have found that leaving a unit in air in the sun can lead to similar internal temperatures, and that stability of the system as the pi and camera throttle their processors to deal with the heat starts to lead weird behavior above internal temps of 85C or so.

How new is your rov, and have you done any electrical system modifications?

-Tony


(chengchang) #6

i am thinking if using the aluminum enclosures will help with cooling


(Anthony White) #7

It certainly should! To maximize the change in thermal conductivity (both because of aluminum and significantly thinner wall) a small fan setup to circulate air around the entire enclosure (conveniently already divided in half with air passages at either end ) should show a measurable difference. Never tried it though!


(TCIII) #8

@anthony-white,

I have run my Heavy Lift BR2 in open air (no thruster operation) for around half an hour and QGC reported an external temperature of 24 deg C and an internal temperature of 54 deg C so 70 deg C or higher is definitely an indication of a component thermal issue.

Regards,
TCIII AVD


(Damon) #9

Just to be safe, I ended up replacing the px4 and power module and now temps are stable at 40C even after hours of heavy use. I also ended up installing a small 30mm cooling fan inside the enclosure. I’m not sure whether or not that decreases the internal temp by any significant amount but it probably doesn’t hurt to have it in there.
With that I assume that the flight controller (px4) may have been shot. Even when only powered via the micro usb the internal temp would rise to 70ish degrees C. Maybe the internal temp sensor was broken, who knows, the main thing for me is that its working fine now.