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BBSHD Temp Sensor?

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  • MtDandy
    replied
    Yeh Ive seen the same on my mobile phone at times on hot days if you leave em in direct sunlight so I wasnt to worried that it wouldnt fade away.

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  • calfee20
    commented on 's reply
    My screen does the same thing on hot days and bright sun. I'm glad to know I am not the only one. I was starting to wonder if I had done something wrong.

  • MtDandy
    replied
    Good topic, Thanks. I live in Australia were the summer temps are often over 30C. Ive installed the BBSHD and 25 amp battery to a 26" MTB. Im 75kg and the bike gearing is 42 front-11-34. I live on a mountain, mostly forested. There is many bush tracks at 1 in 10 degrees steepness. I was out riding in 32C temps for over 40km in rugged terrain rocky bush tracks the other day and after a good few minute climb of a hill ( which was nearly too steep to walk up) I stopped at the top to check the temp of the motor casing. Was too hot to keep my hand on so I thought, lets test this heavy duty unit out. I continued to keep climbing hills around the forest with one short break at a stream for a drink of water. The motor was unable to cool down properly as i was continually climbing hills at slow speed (in 1st and 2nd gear) therefore the motor was unable to utilize any full air movement over the fins to cool. (there was no wind either)
    I was very impressed with the motor on this occasion and am thinking of adding some bigger fins or similar to help the motor along a bit with its cooling.
    I also have acquired a 30T Luna mighty mini chain ring. Im keen to see how that chain ring compares to the Bling 42T when it comes to similar riding the BBSHD in hot conditions.
    One other thing i noticed around 32C was that the DCP-14 color screen in direct sunlight made a black spot on the screen. It faded once i moved it out of direct sunlight, Im now curious to see how it goes in direct sunlight at over 32C the next week or so.
    Cheers all
    Last edited by MtDandy; 01-07-2017, 05:29 PM.

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  • Sebz
    commented on 's reply
    Right now the nylon gear is the know mechanical weak point of the BBSXX, There is nothing right on the market that can replace it, I would love to get a better quality gear still made of higher grade of nylon, plastic or composite but I think this wheels acts as a buffer, a weaker point that can be replaced relatively easy and cheaply. I rather strip this gear than replacing the crank shaft or the motor shaft... I'm no mechanical engineer but lets say we build a replacement gear made of metal like the other gears. I'm pretty sure that the replacement gear would be higher grade of metal than the OEM gears so the weakest point could become the strongest point and could with time and higher power destroy the crank shaft gear or the motor shaft gear....I'm pretty sure with all the metal shards in the mix and replacing the other parts could lead to high $$$$ repairs.
    Last edited by Sebz; 05-15-2016, 07:41 AM.

  • Sather
    replied
    I melted two plastic gears in my BBS02 s and didn't even harm the controller with the old lower power mosfets. (I was running a 32 tooth chainring ) The BBSHD uses the same plastic gear. I run my BBSHD much harder than the BBS02s with no problems so far. When Karl installed a Lyen controller and ran 65 amps through his BBSHD, the plastic gear was the part that failed.
    I’ve been threatening to run my BBSHD though my 65 Amp 18FET Lyen controller to anyone who would listen since I got it 3 months ago. I finally got around to smoking it, and as I wagered, the …

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  • Sebz
    replied
    Nothing to add on what JP said about controllers, I'm pretty sure he verified the info on the FETS, Tumbs up JP.... I'm more worried about motor temps, but again running 30 amps is very low... I would only put a temp sensor on a modded BBSHD at 40 amps or more and not on the controller but in the motor windings!

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  • CraigAustin
    replied
    I'm pretty sure mine exceeds that temperature every day, no problems so far.

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  • Louis
    replied
    Spot on JP!

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  • JPLabs
    replied
    I'm not sure how Karl arrived at his temperature guidelines. They look pretty conservative to me. 140F is only 60C. That's pretty low as an excursion limit ('do not exceed' limit) for this type of device. It looks more like a continuous (average over life) guideline, to me. But, for knowing when to back off to avoid killing the controller, it's the excursion limit which matters.

    The location where temperature is measured within the controller is of utmost importance for establishing a working temperature limit. So is the response time of the measurement. That aquarium thermometer has a big, slow sensor, which can only measure an average temperature (both location and time), and it's on the wrong side of the potting compound in the controller, so it's not much good for fast measurements needed to monitor the excursion limit. But for continuous limit temperature, the slowness and vagueness are OK.

    --

    Are the MOSFETS at risk from failing due to over-temperature? Well, let's see. The 3077 MOSFETs reportedly used in the BBSHD controller can still handle 120A each, even when their device (the MOSFET case) temperature is 125C. That's 257F. They can still handle 40A at 160C (320F). They only handle a few amps in this application and are being used pretty gently, from what I can tell.

    The BBSHD MOSFETs have pretty decent heat sinking, too. The MOSFETs are bonded to an aluminum heat sink, which is bonded to the controller housing. They don't make that much heat in this application, and the thermal resistance of the MOSFET is 0.5C for every watt of heat (not power) they reject. So, the MOSFET case temp won't be too different from the controller housing temp.

    That means the motor controller housing would need to be way too hot to touch, probably hot enough to boil spit, before the MOSFETs would be killed by temperature. So, no, I don't think you can cook them in this application, as long as you can hold you hand on the controller case without getting burned, anyway.

    You could still kill them electrically. But that's not the issue at hand, here.

    --

    If not MOSFETs, then what is at risk, thermally? It's probably the capacitors in the controller which will limit it's operating temperature over the long term.

    MOSFETs fail almost instantly if used beyond their thermal/current/voltage limits. But capacitors just age faster if run too hot. About 2x as fast for every 10C increase. Running capacitors hot isn't going to instantly kill them. Running them too hot all the time will shorten the working life of the controller.

    So, I think Karl's numbers look very conservative, probably set up to ensure a good, long useful life, but quite a bit lower than you can go for the short term. From what I'm seeing, I suspect that 100C (212F), as measured inside the controller, would be OK for short term non-abusive riding. Like climbing a long hill in a reasonable gear.

    Due to the slow time response of measuring the controller internal temperature, this logic applies for reasonable use. Riding. If you pull up to a wall and stall the motor at full current for too long, sure, you might be able to cook the controller before it gets to 100C at the measured location. But we are talking about usage guidelines here. Reasonable, average temperatures. Temperature sensing inside the case, as described by the OP, is too slow and vague for anything more precise.

    I'd love input with additional insight about what other controller components might influence the thermal limits. Are there devices in there which are more sensitive to high temperature than the capacitors?

    I originally planned to add a thermocouple to my MOSFET heat sink, but it runs so cool I'm not even worried about it anymore.

    --

    I don't think I have seen a SINGLE case of a user's confirmed temperature-based BBSHD controller failure. Wiring issues, infant mortatality, display malfunction, etc, sure. But not smoked controllers. Has anybody else?

    This BBSHD controller might even have temperature protection built-in. I haven't seen an official specification which says so, but I suspect it does.

    Their reputation for being bulletproof controllers seems very plausible, to me, with respect to operating temperature. I do have a spare now, and I continue to play with my settings, but so far it just takes all I've thrown at it, without getting nearly warm enough to concern me.
    Last edited by JPLabs; 05-14-2016, 10:50 AM.

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  • Lance Tesla
    replied
    I used to make a habit of putting my bare hand onto my BBSHD at the top of every long hill until I realized that it would barely get warm. If you are really concerned get a cheap optical pyrometer with a laser pointer from Harbor Freight for $10 and shoot various parts of the outside of the drive after a long climb. FWIW, I think the HD part in BBSHD means it's a lot less likely to overheat than the BBS02.

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  • Sather
    started a topic BBSHD Temp Sensor?

    BBSHD Temp Sensor?

    Has anyone put a temperature sensor on the BBSHD? I just put one on my BBS02 and was shocked how fast it jumps to 145 degrees when climbing a steep hill. In his article, Karl felt that anything over 140 was dangerous. Now, I'm a little concerned about my BBSHD.
    Heat is the enemy. Electric motors can often take far more power put through them than their nominal rating, but over time the heat will build up and cause all sorts of problems. Mosfets can blow, …

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