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BBSHD too hot? - before it's powered up???

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    BBSHD too hot? - before it's powered up???

    I parked outside a restaurant for lunch today... Outside temperature... hot... sun... brutal..

    I hear folks say if the motor's too hot to touch you're running it too hard... but what if it's too hot to touch before you even turn it on?

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    #2
    If you can crack an egg on it and have breakfast moments later then you need to ride twice as fast in order for the air to hit the cooling fins.

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      #3
      My strategy was indeed to ride as quickly as possible to do the 3mi to get home.... errrr.... yeah... of course to increase air flow! =]

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        #4
        Paint it white!
        Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

        Comment


        • MoneyPit
          MoneyPit commented
          Editing a comment
          White absorbs less heat, sure. But black shucks it faster when you are dealing with something that generates heat from inside itself, believe it or not. Ever see a white radiator?

        • JPLabs
          JPLabs commented
          Editing a comment
          Moneypit - white radiators, painted? Well, no, but I have compared black with plain aluminum. Close to 'white painted' case. Bare unpainted ones test a tiny bit better than black painted ones. Forced convective cooling coefficient is better with no paint, but the difference is tiny with the very thin paint used.

          Black body radiation is not the dominant mechanism here, convection is; that's my point.

          If it was a satellite in a vacuum, or another application with true 'heat radiators', then sure, black would win, due to its higher emissivity.
          Last edited by JPLabs; 07-26-2018, 07:55 AM.

        • MoneyPit
          MoneyPit commented
          Editing a comment
          JPLabs - My experience doing heat testing on coolers and under-hood materials in automobiles (mostly intake parts but also stacked-plate oil and transmission coolers (Earl's, Setrab etc.) shows pretty much what you describe. Plain alloy is better than painted alloy, but not by much so long as you don't do something stupid like use thick paint. I spent some time talking with the Earl's Plumbing engineers and they found that the benefit of an unpainted cooler was a) slight and b) outweighed by the benefits of sealing the exterior. Earls went with silver paint, btw., after testing black vs. silver.

          Would white vs. black make a measurable difference? No idea. Especially at this level. But since we'd be talking about a cpu cooler and a weak pump to circulate cooling fluid of some kind, I'd still want to put my best foot forward on G.P. And by the way... I was looking for big CPU radiators and came across 360mm ones... You gotta love those zany Chinese ...

          https://i.ebayimg.com/images/g/10oAA...5B/s-l1600.jpg

        #5
        I am wondering about using computer CPU heat pipes/radiator to cool down the motor ? did you hear about that ? I do not know what is the cutting power of these cooling devices...
        otherwise I was thinking about thermally connecting the motor to the bike frame in aluminum in my case and use the frame as cooling surface or heat buffer.
        For sun protecting, yes white painting is fine. you may have to look at low emisivity paint. they are not all white actually ...
        food aluminum foil ?

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          #6
          this would work fine I guess !
          I want to try ...

          Attached Files

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            #7
            On Thursday we will break our record of consecutive days over 100 degrees fahrenheit. Currently its 21. We'll beat it by several days from the looks of things.

            So I have been working on this issue myself. In 100 degree heat and with extended PAS and throttle on a flat ground commute, I was seeing 145-degree casing temps. By adding heat sinks, I got that down to 120 degrees under identical weather and riding conditions.

            But... it has gotten hotter. Even trying to take it easy on the bike I measured 160 degrees WITH the heat sinks a couple days ago. A complicating factor was I was doing a much longer ride.

            For the end cap, I used 4 layers of thermal adhesive to provide full contact to the motor in the logo center.

            Don't bother trying to paint the motor white. Just get a cheap shop rag and lay it over the thing. White paint would help reflect sunlight but it would also inhibit shucking heat coming from within. All you need is a crummy old hand towel to take that direct sunlight beam off of it. And nobody is going to steal a rag. I hope.





            Comment


              #8
              I don't do a thing to prevent a hot motor. It is often exposed to hard riding at >110F, 750W continuous for miles after sitting in the sun. 3500mi and still going strong.

              I'm not planning on changing my habits unless it starts to become a problem and I'm replacing stuff.

              Comment


              • AZguy
                AZguy commented
                Editing a comment
                It was meant to be tongue-in-cheek

                It's AZ and things get brutalized by the sun - oh well....

              • MoneyPit
                MoneyPit commented
                Editing a comment
                Well its good to know it can handle heat like that. When my Cyclone got to 165 surface temp it shut down. I don't want my controller to fry, although that would be a good excuse to beg for a Ludi.

              • AZguy
                AZguy commented
                Editing a comment
                Sort of how I look at it - if I manage to destroy a controller - beef up a new one or get one already beefed up.

                I'm pretty sure destroying a well greased BBSHD motor is a challenge but if/when I do, the postmortem would be interesting...

              #9
              Yesterday it hit 48°C (118°F) and I was invited to a schmooze about 8mi of all multi-use paths so I figgered, why not?

              When I got there the only good place to park was in the direct sun.

              When I left everything was crazy hot with the motor too hot to hold and the air temperature keeping steady 47-48°C - at least I had a few beers in me to hydrate myself (tongue-in-cheek! ;-} )

              I ran hard on the way back, about 80% 750W and most of the rest at ~500W.

              When I got home the motor was too hot to touch for more than a second or so.

              Oh well =]

              Comment


              • Hard Tail
                Hard Tail commented
                Editing a comment
                I’m shivering through a southern winter here trying to remember what it was like to be warm.

              • AZguy
                AZguy commented
                Editing a comment
                A trip here will snap you out in a hurry... I know Melbourne is milder than Brisbane but I spent time there in the summer and.... well it's only six months away and you may be reminiscing on the shivering by then =]

              • Hard Tail
                Hard Tail commented
                Editing a comment
                Had the pleasure of two trips to AZ on business, both mid summer, and just love that desolete landscape. Must be gods on country for ebiking but it sure was hot. Nice dry heat though. They even had ebike taxis in the centre of Phoenix that got me to and from a very memorable Irish pub. Ah, memories of being warm.

              #10
              Dang... Its only 104 here in Central CA. If you come to visit don't forget your sweater.

              I am about to hit the road for home. I switched to my AWD hub bike for riding in this heat a few days back and I measured motor surface temps yesterday... 105 ambient temp and motor temps were both 115. Peanuts. For giggles I may try and run my other AWD that has a BBSHD in the back to see how much less it heats up when it has a helper. A lot I bet.

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                #11
                Next time I've got a bag on the bike and it's stinking hot (they're saying we'll see 45°C again) I'll try and remember to bring the IR thermometer and see if I set any records ;-}

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                  #12
                  A CPU cooler can have a low temperature differencefrom the cold to hot end. I think you will be limited by getting heat into the cold end, though. If the MOSfets are basically mounted to it, might make some improvement. Needs to be vertical, to work well, though.

                  Here's what I do with them, "Candle Amplifiers" I call them, because they make more light than the candle which powers them:

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                  Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

                  Comment


                  • JPLabs
                    JPLabs commented
                    Editing a comment
                    Yes, right. From an old 12V cooler, mounted at bottom of the large cooler.

                    There's another small heat sink below that, to catch the flame and spread the heat.

                  • paxtana
                    paxtana commented
                    Editing a comment
                    Neat, always wanted to play with one. For years a few friends have been brainstorming using a TEG in conjunction with any LENR reactor showing a high enough coefficient of performance that you end up with more electricity than what is consumed to run the reaction. Currently most commercial reactor development focuses on use as a boiler which is obviously a lot less exciting.

                  • Interscape
                    Interscape commented
                    Editing a comment
                    Cool projects!!

                    What if you were to attach a peltier junction directly to the motor? Do you think the voltage you could generate would be usable for regeneration? Granted it would only be about 12 volts but possibly a step up transformer?

                  #13
                  great idea to generate bike light suing motor heat :)

                  Comment


                    #14
                    I just installed this heatsink and it decreased the temperature at the end of my usual ride by about 5 degrees.
                    https://www.luxeonstar.com/60mm-roun...lpha-heat-sink

                    Comment


                    • Interscape
                      Interscape commented
                      Editing a comment
                      How did you attach it?
                      Last edited by Interscape; 07-15-2019, 10:49 AM. Reason: Spelling:

                    #15
                    My BBSHD build has turned 5000mi and survived two AZ desert summers so far... ridden very hard... we've had a remarkably mild May but the hot stuff is around the corner...

                    Last year's monsoon provided some insane weather... Rode in 50°C (122°F) - I don't recommend that... I got caught in a dust storm with 50mph winds that nearly knocked me off the bike and visibility would go from about 5-10m to 1-2m in a heartbeat and seeing the gusts of the low visibility dirt blowing across and in front was surreal (and dirty - every pore got filled)... in another I was rushing home seeing an intense cell only about a quarter-half mile across and stayed dry until.... I turn the last corner to my house about 200m down the road and can see my next door neighbor's house just fine but mine was shrouded in what can only be best described as a waterfall... I hit a literal wall of water almost at my driveway and even though I only had to traverse 10-15m through it was soaked to the bone in seconds... A quarter mile away it didn't even get wet...


                    Hopefully the bike survives another summer! It's looking a bit beat but still holding up well... I've got my money's worth from it so I see every extra mile as a dividend... Heat be damned!!!



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                    Last edited by AZguy; 05-30-2019, 05:55 AM.

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