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Pike's Peak Special: 2023 Unfinished Business

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    Pike's Peak Special: 2023 Unfinished Business


    In Aug 2022 I documented a BBHD-Ludi V2 build and the ebike race up Pikes Peak on this forum. Link is https://electricbike.com/forum/forum...s-peak-special
    I had some unfinished business. It took a disappointing 44 minutes.

    Last year, pilot error (ignorance?) overheated that setup to shutdown at least 4x. I still got up 4700' and 12.5 miles in 44 minutes, 2nd fastest, but the V2 has way more to give. I DQ'd myself, the race classes page says "Ebike unlimited" but the registration page asked if you were class 1,2 or 3. A young lady on a Biktrix earned that legit. I was there apparently to weld a BBHD to my frame.

    This year, August 12, 2023, on the Same Luna BBHD and Ludicrous V2 controller , 1500 hard miles later, 10lbs heavier bike. I rode up in under 32 minutes. Yes, 12 minutes faster. Next bike in was 6 minutes off. This is likely the second fastest ascent on a kit bike, Adam Griffin owns that honor which is well documented https://www.electricbike.com/hub-motor-pikes-peak/

    The rest of this thread is thread gives details of what I learned and what I did to mitigate the heat problem and put a fast run in to the top. Yes, a BBHD was harmed in this process, but it is still able to easily break 45mph and clocked over 50. These things are crazy tough even after 1000's of miles offroad and hard climbing. Brilliant Luna Cycle - well done. What this BBHD puts up with exceeds even unreasonable expectations!



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    Last edited by jnord; 09-26-2023, 05:03 AM.

    #2
    When I got home from the 2022 race, put the Ludi V2 back on my Banshee Prime (6" travel, 29er 2.4 DHF's at a15psi), and started trying to figure out the heat issue. I had been up at 4am, raced at 6:15am, finished around 7am, rode down from 14K' back to 9300' , drove home, and needed to know. I mapped out a 1500' climb/5.5 miles up a gravel road near the house (Mt Herman Road for those of you front range Colorado). I took off on my test course - and overheated easily at the current and rpms I was attempting to run that race at. I ran that test course about 20x, measuring the outside ambient temp, the temp of the motor case, timing and data from an eggrider and the V2 VESC bluetooth. This is a rough winding USFS road - I put that Luna BBHD through many rides that "tipped it over" into thermal protection at 100c , and many more where I backed down the current to hold 99c or less. All on bumpy, dusty dirt, often over 20mph - passing cars uphill on occasion, using all of the road to get around corners,

    I set max current to 30amps, running 52v and 72v batteries from bicyclemotorworks.com:
    • 52v 16ah Samsung 40T 60amp continuous
    • 72v 8ah Saumsung 40T 60amp continuous

    These Ludi controllers will let the uninitiated turn their bbhd into a space heater - energy wasted that I needed to improve my time up the Pikes Peak course. I thought it was current - trying to run 30amps continuous, bursts to 60amps was the issue. It was, but low rpms also hurt. And the heat was trapped.

    One thing stood out in all those test runs - it could be 70 degrees outside or 44 degrees - I could do 15 mph or 30 mph, if I put in the same current the BBHD it overheated within 50 yards every time.
    The BBHD does not shed heat. Pour ice water on it while you ride , it will overheat. Ride it below 32 degrees and your BBHD will overheat. Ride 30mph into a 30mph headwind - those cooling fins will not do a dang thing. The internals are not designed to enable the case to exchange thermal heat from the amps I was throwing at it combined with rpms that turned out to be way too low.

    (cont)

    Comment


      #3
      The overheating issue is 100% caused by a throttle - happy pilot. The current, field-weakening, and optimal erpms are well documented in the ludicrous documentation thread. Without Marcos, and all the contributions there, I'd never have shed enough ignorance to get up the big hill.

      At first I figured there was some field-weakening induced heat. There are about 3 downhills on the Pikes Peak climb. And I had the throttle pinned so probably had some. However, I figured my 90rpm cadence was more important than getting the BBHD rpms high. The 2022 max speed was 40, avg was just over 17mph, engine rpms averaged 6800. I put in 28amps avg, d-axis current avg was .002 - there was no field weakening.

      It was all current, at least that is what I first thought. So I tried the following with a 30amp max threshold set:
      • 72V batteries. Yep, running 30amps at 72v was faster, but heated the same.
      • 52v batteries with low charge. Slower,surprise, but 30 amps heated the same
      • high ambient temps
      • low ambient temps
      • headwinds
      • 12v cooling fan direct on the fins
      • flats
      • hills
      • etc
      The same outcome - 20-25 amps was it, more than 25 and the temp climbs past 97c. 30 amps and it tips over every time. Once hot, it really gets hard to get the temp to drop if even 10amps is pushed through it. I owe some data on all this. I'll get a rollup and any of the csv files loaded that are of interest.
      Last edited by jnord; 09-26-2023, 07:38 AM.

      Comment


        #4
        I pulled the BBHD apart, cleaned, new grease etc. I wanted to see if the case was in contact with anything that could convect heat. Not that I could tell, in fact it appeared that the thermal mass that gets hot (and stays hot) is isolated from the case by air-gaps and thermal non-conductive insulation. The behavior I was seeing made sense - the copper windings got hot first, then as heat transferred to the rotor, that is when it had a hard time cooling down. These BBHD's handle bursts of high current all day long, but a sustained 25amp climb will heat the rotor then game over while you wait for it to cool (or hopefully let off the throttle). Pic of the rotor and case where the windings and magnets drive the rotor.

        Comment


          #5
          I pulled the BBHD apart, cleaned, new grease etc. I wanted to see if the case was in contact with anything that could convect heat. Not that I could tell, in fact it appeared that the thermal mass that gets hot (and stays hot) is isolated from the case by air-gaps and thermal non-conductive insulation. The behavior I was seeing made sense - the copper windings got hot first, then as heat transferred to the rotor, that is when it had a hard time cooling down. These BBHD's handle bursts of high current all day long, but a sustained 25amp climb will heat the rotor then game over while you wait for it to cool (or hopefully let off the throttle). Pic of the rotor and case where the windings and magnets drive the rotor.

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          Those tunnels in the rotor gave me a really bad idea: what if I vented this motor and pushed air through it? CAUTION: If you had a warranty left on your BBS02 or BBHD, this will certainly void it:
          I drilled vent holes in the case. 4 on the hot side for egress, two that are mid-case for input. I then tried an air pump for boat holding tanks to push air, ended up with a small $15 USB powered inflator for camping airbeds. I powered it with a 20v/2ahr battery under my seat. Ran the air hose down the downtube to the BBHD case.

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          Attached Files

          Comment


            #6
            The change was dramatic with the now vented bbhd:
            • I could run 8 more amps sustained without overheating
            • I dropped 4 minutes on a 22 minute test run.
            • overall 22% improved with very little air exchange
            • Notice the Pikes Peak 2023 avg of 35.5 amps. It is higher than the tests because of using a more powerful blower to exchange air. That was 35.5 amps over the entire 32 minute race.
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            Last edited by jnord; 09-29-2023, 05:06 AM.

            Comment

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