Over-heating
- Thread starter baker55
- Start date
I was just looking in Mission Cockpit to see if this is one of the stats it can report using the speech module, unfortunately its not in the list in the version I have. Would be a nice upgrade to M/C to have it be able to call out the BL temps as you're flying. I have it setup on my netbook to report battery voltage, altitude, and distance from home as the Mk flys, nice to be able to just concetrate on the flying and have the computer tell you what's going on with the MK.
Heatsinks on the BL's are a nice idea though the problem with that is if you do install them they must be glued on with thermal epoxy which essentially makes it impossible to ever change a FET if one goes out. I wouldn't consider using them without gluing them down, if one happens to fall off and short some components you could lose a lot of expensive electronics, not just from the short, but also from the resulting crash.
Ken
Heatsinks on the BL's are a nice idea though the problem with that is if you do install them they must be glued on with thermal epoxy which essentially makes it impossible to ever change a FET if one goes out. I wouldn't consider using them without gluing them down, if one happens to fall off and short some components you could lose a lot of expensive electronics, not just from the short, but also from the resulting crash.
Ken
Bartman
Welcome to MultiRotorForums.com!!
why do you suppose the heatsinks have suddenly become such a must-have feature? are they really that necessary?
while we're contemplating call-outs, I'd like to have "Motor-failure" in a pleasant female voice if/when it happens. also, can she address me as Master Skywalker? for example, "Motor failure, Master Skywalker". I can be such a dork sometimes!
while we're contemplating call-outs, I'd like to have "Motor-failure" in a pleasant female voice if/when it happens. also, can she address me as Master Skywalker? for example, "Motor failure, Master Skywalker". I can be such a dork sometimes!
The quick answer is with the relatively recent introduction of big motors on heavy lifters the limitations of the MK BL boards is starting to be a lot more noticeable. The quick and easy answer is to glue some heatsinks to the FETS to try and keep them from dying due to overheating, the harder solution is to redesign the board for the new application and make it able to withstand the temps and current flow that big motors can generate.
Actually I believe it is possible to have M/C address you that way, problem is you're limited to the very mechanical sounding voice that's built into the speech module, it ain't like your GPS where you can get a sexy female voice to tell you where to go
Ken
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Sorry to arrive late on this thread. As Matwelli quite rightly stated, temps over 80-ish should be avoided at all costs, for any electronics. It's a reliability issue, just like we were discussing in another thread. ESC failure is the number one reason for MRs falling out of the sky and heat is often the culprit. It's a cumulative thing too - running hot may not kill the ESC on that particular day, but it will contribute to it dying young. The other big ESC killer is vibration, which will compromise the solder joints. Ironically many people seek to avoid the heat problem by strapping the ESCs directly to the arm and thereby encounter the second problem. If you do zip-tie them to the arms, definitely you want to be putting some suitable anti-vibration material between them and the metal.
Another quick point about heatsinks that didn't really come up in this conversation - without airflow they are absolutely useless. Glue a heatsink onto an ESC that's sitting in zero airflow and it will still overheat. A heatsink merely facilitates the passage of heat from the component into the air and since air is such a poor conductor it needs to be moving - vigorously - in order to conduct away the sort of heat that a stressed MOSFET can generate. Raising the dome a few millimeters may help if your flying style/mission involves constant forward airspeed but if you're hovering in place for extended periods, it won't help much.
Another quick point about heatsinks that didn't really come up in this conversation - without airflow they are absolutely useless. Glue a heatsink onto an ESC that's sitting in zero airflow and it will still overheat. A heatsink merely facilitates the passage of heat from the component into the air and since air is such a poor conductor it needs to be moving - vigorously - in order to conduct away the sort of heat that a stressed MOSFET can generate. Raising the dome a few millimeters may help if your flying style/mission involves constant forward airspeed but if you're hovering in place for extended periods, it won't help much.
Droider
Drone Enthusiast
Jes you are just brimming with knowledge.. how many organic hard drives you got!
Could I ask what kind of temperature can we feel relatively safe with, like it wont degrade the thingymabobs. I don't seem to get above 62/63ºc and thats in a fully loaded 8 min hover, If I am flying around I see between 48 & 54ºc. Oh MK BL2 whatsits.
Dave
Could I ask what kind of temperature can we feel relatively safe with, like it wont degrade the thingymabobs. I don't seem to get above 62/63ºc and thats in a fully loaded 8 min hover, If I am flying around I see between 48 & 54ºc. Oh MK BL2 whatsits.
Dave
Just one organic hard drive, but it's going soft, rapidlyI'm no electronics engineer, but... looking up the data sheet on the Atmega168 (the processor used on the BL2.0), it specifies an operating temperature range of -40 to 85 degC. So what the mfg is saying is that if you try to run it at 86degC, they won't guarantee anything! Ergo you should be staying WELL clear of that sort of temperature. Personally I'd peg the absolute maximum allowable temperature at 65degC (20degC below the quoted max) but I'd try to design the installation to produce a max of 45degC. Remember you must be mindful of the ambient temperature, too - if the ambient is 25degC and your installation produces 45degC in the ESC, then at an ambient of 35degC it will be running at 55degC (more or less).
Remember too, that the temperature sensor in the BL2.0 is actually inside the Atmega168 - so by the time THAT sees a temperature of 85degC you could be frying eggs on the MOSFETs themselves!
IMHO any "heavy lift" MR should incorporate specific measures to ensure the ESCs run at VERY moderate temperatures. Like the saying goes: you can never be TOO rich and your ESCs can never be TOO cool!