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Thread: Busch+Müller B&M Lumotec IQ cyo senso plus: connection battery polarity

  1. #1

    Default Busch+Müller B&M Lumotec IQ cyo senso plus: connection battery polarity

    I modified my bicycle to an ebike. I replaced my SON28 dynamo by a fronthubmotor but I like to keep using my B&M Lumotec IQ cyo senso plus front light and my B&M Toplight Flats S backlight.

    My batterypack has an USB port I hope it can be used for feeding my lights. I want to use a Pololu 7.5V Step-Up Voltage Regulator U3V70F7 (link) to bring my USB up to the necessary 7.5V.
    From the front light one double wire is (was) going to the Son28, the other double wire is going to the backlight. In the manual of the Lumotec IQ cyo senso plus (link) is written “If you connect the headlamp to a rechargeable battery (entirely at your own risk) make sure to observe correct polarity, i.e. "plus" to the earth inlet and "minus" to the current inlet.

    I like to know how to connect the U3V70F7 to my Lumotec IQ cyo senso plus:


    1. Can I use for my U3V70F7 (which is connected to my USB) the same entrance cable as was used by my Son28?
    2. If so, how to connect the right polarity?






  2. #2
    Flashaholic* Steve K's Avatar
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    Default Re: Busch+Müller B&M Lumotec IQ cyo senso plus: connection battery polarity

    There may be problems with this concept. Many/most dynamo lights rely on the dynamo to limit current to 0.5A. If they are connected to a power source that can deliver quite a bit more, it is possible to severely damage the light.
    I've seen a Supernova light that was connected to an ebike's battery, and just about every semiconductor in the light was destroyed. Granted, the voltage may have been too high too, but it was the current that damaged most of it.

  3. #3

    Default Re: Busch+Müller B&M Lumotec IQ cyo senso plus: connection battery polarity

    Quote Originally Posted by Steve K View Post
    There may be problems with this concept. Many/most dynamo lights rely on the dynamo to limit current to 0.5A. If they are connected to a power source that can deliver quite a bit more, it is possible to severely damage the light.
    I've seen a Supernova light that was connected to an ebike's battery, and just about every semiconductor in the light was destroyed. Granted, the voltage may have been too high too, but it was the current that damaged most of it.
    Despite your warnings I tried... it seems my B&M is not that touchy. Wrong polarity with 7,5V..no ligth at all..right polarity.... yes, it works!

    Following table might be of help for any others.


    Please note the best one is the cheapest ...... 4,42 Euro only! https://nl.aliexpress.com/item/2000-...OrigTitle=true2000
    Please note the B&M concerns a combination of front- and backlight!

  4. #4
    Flashaholic* Steve K's Avatar
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    Jun 2002
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    Peoria, IL
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    Default Re: Busch+Müller B&M Lumotec IQ cyo senso plus: connection battery polarity

    very interesting!

    I've got a dead B&M Eyc that I've been meaning to reverse engineer. With any luck, maybe I'll figure out what they do in order to behave like this.
    It does appear that they use a switching converter, so it might be regulating the current to the LED.

  5. #5

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