jari Posted November 30, 2014 Share Posted November 30, 2014 During the summer a lot of bashers will lower their gearing to compensate for higher temps. Racers don't bother because they're racing in short heats, so the high temps of "battle" aren't sustained for long periods. Good fans do make a difference by forcing cooler air over the heatsinks, this speeds up the heat transfer and dissipation into the surrounding air. So yes, active rather than passive, passive on ground vehicles isn't fast enough. In aircraft, the forward motion of the plane is used to pass air at speed over the ESC. This is why you won't normally see fans on aircraft ESCs. Ergo, passive cooling with ducted air is sufficient. My head hurts. yes possibly a bit much for sunday night.. I did look up "temperature effects and heat dissipation on brushless motor " on google, but again the results were not good for sunday night ended up here: http://www.pittman-motors.com/Portals/0/Resources/Temperature_Effects_On_DC_Motor_Performance.pdf There must be a cumulative effect of fans, heat sinks etc. I wonder how much difference using something like thermal paste between motor and motor mount would make? or between motor and heat sink? Or is there any way to increase the efficiency of heat transfer in the motor itself? eg. thermal paste between the windings and the motor body? but again - all this is to work around a problem that can be worked around in other ways. i.e. instead of wacking in a high kV motor... pay attention to the numbers and go high voltage, low resistance. Another thing that is not obvious and needs numbers... and that is the low load current draw. e.g. how much of a motor time for a basher is spent doing not a lot? and how much on full throttle? all that time doing not a lot and the motor is still creating heat isn't it? If you have 4A no load draw... then does all that current get turned into heat if the motor is not turning? versus say 100A draw at 95% efficiency - where 5A goes to heat. 95 to kinetic energy? Tell me to stop. Quote Link to comment Share on other sites More sharing options...
Tug Posted November 30, 2014 Author Share Posted November 30, 2014 Let's be clear, I'm not having motor heat issues, it's the ESC I'm trying to protect. In answer, you're absolutely right, a member on here recently almost cooked a motor by spinning the wheels up to approximately half speed by using the throttle trim. This was with the wheels off the ground, so virtually no-load. This is said to be very inefficient and so caused the motor to rise in temperature quite quickly. Yes, lower temps are achieved in other ways. Lower gearing, lower Kv with higher voltage etc. I used to frown on motor fans, now I have three cars using them! I'm not running any set-ups that really need a motor fan, I just decided to be cautious. Quote Link to comment Share on other sites More sharing options...
jari Posted November 30, 2014 Share Posted November 30, 2014 Let's be clear, I'm not having motor heat issues, it's the ESC I'm trying to protect. In answer, you're absolutely right, a member on here recently almost cooked a motor by spinning the wheels up to approximately half speed by using the throttle trim. This was with the wheels off the ground, so virtually no-load. This is said to be very inefficient and so caused the motor to rise in temperature quite quickly. Yes, lower temps are achieved in other ways. Lower gearing, lower Kv with higher voltage etc. I used to frown on motor fans, now I have three cars using them! I'm not running any set-ups that really need a motor fan, I just decided to be cautious. ahhh ok. - protecting the ESC. Understand. Don't see a problem with fans or heat sink - all to get heat away from the motor. lets face it, one small heat sink must almost double the surface area compared to a motor on its own. Getting out of my comfort zone.. what is it that drives heat in an ESC? is it purely current? or do other factos come into play? Quote Link to comment Share on other sites More sharing options...
Tug Posted November 30, 2014 Author Share Posted November 30, 2014 Yeah, finned cans are so much more efficient at heat dissipation, the mind boggles! In the ESC it's mostly current draw, but it's also the continuous switching from phase to phase, up to 13,000 times a minute on some ESCs! That's quite the workload! Quote Link to comment Share on other sites More sharing options...
rushboy2004 Posted November 30, 2014 Share Posted November 30, 2014 highest recorded current draw from the 380kv was 113 Amps. I got a 58110 380kv for my Losi 5. Don't leopard rate the 380kv motor having a max draw of 82amps ? thats a big difference - 31 amps guess the leopards margin for error is near 25% Out of interest how do you measure your useage/current draw? Quote Link to comment Share on other sites More sharing options...
Tug Posted December 1, 2014 Author Share Posted December 1, 2014 I got a 58110 380kv for my Losi 5. Don't leopard rate the 380kv motor having a max draw of 82amps ? thats a big difference - 31 amps guess the leopards margin for error is near 25% Out of interest how do you measure your useage/current draw? It's a lovely motor, but can cog like a Biatch! I was surprised at the discrepancy between the stated max current and what I actually measured, but my device may not be all that accurate. However, I don't believe my ammeter is that inaccurate. Still, 113 Amps ain't bad! I've got smaller cars pulling more! It's a plug in device I got from HK. They're not expensive and sit between the cells and the ESC. It's only rated to 130 Amps, so has its limitations, but still damn handy. I've never found one with a higher rating than that, but I'll keep looking. I'm gonna get some footage soon, she's going just how I want her. Quote Link to comment Share on other sites More sharing options...
Tug Posted January 11, 2015 Author Share Posted January 11, 2015 Got some fresh footage for you all, only on road, but it'll give a good indication of how fast this thing is. 2 Quote Link to comment Share on other sites More sharing options...
sean-vrs Posted January 11, 2015 Share Posted January 11, 2015 looking good! 1 Quote Link to comment Share on other sites More sharing options...
Tug Posted January 11, 2015 Author Share Posted January 11, 2015 Yeah, she's a hoot to drive! Plenty fast, low temps, but that might change come summer, that'll be the real test of the set-up. Quote Link to comment Share on other sites More sharing options...
sean-vrs Posted January 11, 2015 Share Posted January 11, 2015 Yea seems well planted, what runtime you looking too achieve? Quote Link to comment Share on other sites More sharing options...
Tug Posted January 11, 2015 Author Share Posted January 11, 2015 As close to thirty minutes as I can get, a half hour would be great, but that might be asking too much. Laws of physics, to shift X amount of mass requires Y energy. I just hope I can see a noticeable improvement, I'm confident. 1 Quote Link to comment Share on other sites More sharing options...
Tug Posted January 29, 2015 Author Share Posted January 29, 2015 Not mine, but this is a Super 5sc flux! Sorry about the pic, it's a screenshot from YouTube. 1 Quote Link to comment Share on other sites More sharing options...
Tug Posted February 2, 2015 Author Share Posted February 2, 2015 Tonight I swapped ESCs. The little MGM is too good to be pushed to its limits, so I've fitted something cheaper. Full update in due course. Quote Link to comment Share on other sites More sharing options...
jony nitro Posted February 2, 2015 Share Posted February 2, 2015 Come on! Quote Link to comment Share on other sites More sharing options...
Tug Posted February 3, 2015 Author Share Posted February 3, 2015 All in good time! Pigging snow has arrived, can't do any testing. Quote Link to comment Share on other sites More sharing options...
Oh How Original Posted February 3, 2015 Share Posted February 3, 2015 I think the picture you posted says you can Quote Link to comment Share on other sites More sharing options...
Tug Posted February 6, 2015 Author Share Posted February 6, 2015 Another smashed rear diff, I'm puzzled. You could say "don't be a tool, you're running 8s, Duh!", but at just 380kv the drivetrain isn't being over revved. The damage is difficult to conclude from, but it could've been the crown screws coming loose again, then when far enough out they were snapped against the bulkhead. New diff cup fitted, red threadlock applied. Will not give up on this truck! Other point to consider is I no longer have the slipper clutch. So I've lowered the launch control to soften the impact of hard acceleration. I've also softened the brakes, they were set a bit strong. To protect both the drivetrain and the ESC, I've lowered the voltage to 7S, should still be quick enough. Testing and vid to follow. End transmission. Quote Link to comment Share on other sites More sharing options...
sean-vrs Posted February 6, 2015 Share Posted February 6, 2015 Sorry hear of your misfortune, You going stick at it with this motor? Quote Link to comment Share on other sites More sharing options...
Tug Posted February 6, 2015 Author Share Posted February 6, 2015 Absolutely! Best motor I've ever bought! I'm not convinced that it's the motors fault, I think it was just the diff coming apart. Hopefully red threadlock will cure that. Quote Link to comment Share on other sites More sharing options...
sean-vrs Posted February 6, 2015 Share Posted February 6, 2015 Fingers crossed, I like where this build has got too this the last hurdle or is there more to come.. Quote Link to comment Share on other sites More sharing options...
Tug Posted February 6, 2015 Author Share Posted February 6, 2015 Learn to build the diffs better and sort the stub-axles, that's it for me, job done! Then roll on summer start and driving her in anger. 1 Quote Link to comment Share on other sites More sharing options...
Tug Posted February 7, 2015 Author Share Posted February 7, 2015 HPI Super 5sc flux with a new BEC.: 1 Quote Link to comment Share on other sites More sharing options...
sean-vrs Posted February 7, 2015 Share Posted February 7, 2015 That's neat, Which BEC is that? Quote Link to comment Share on other sites More sharing options...
Tug Posted February 7, 2015 Author Share Posted February 7, 2015 It's a Turnigy Dilux, nice kit, but overkill really. You can set an LVD on it that'll Flash a bright light when your cells are low, but it involves guesswork and needs resetting for each different cell count. Best bit is the output voltage, 5.2, 6, 6.8, 7.4 or 8.4 volt output. This is great, but my MGM ESC is OPTO, I don't know what the voltage limit is for the BEC going into the ESC, so I've emailed MGM to find out. In the meantime I'm keeping it down on 6.8, just in case. It's all good fun! Quote Link to comment Share on other sites More sharing options...
sean-vrs Posted February 7, 2015 Share Posted February 7, 2015 Yea that's great I like the multiple output voltages, is it programmed via computer software or all onboard? Quote Link to comment Share on other sites More sharing options...
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