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  1. #1
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    Low Voltage cut-off switch for Home Brew Packs?

    Just wondering if anyone has installed any type of device on their DIY lights / battery packs to cut out when the voltage of the pack gets down to a minimum point. I believe the commercial light systems may have this type of protection, but I'd like to build it in to my home made set-up to avoid over discharging the pack and potentially reversing the polarity of the cells. Any advice on what's been used, or what the appropriate type of device would be would be greatly appreciated.

    Thanks,
    Mark

  2. #2
    some kind of hero...
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    Quote Originally Posted by gubawatts
    Just wondering if anyone has installed any type of device on their DIY lights / battery packs to cut out when the voltage of the pack gets down to a minimum point. I believe the commercial light systems may have this type of protection, but I'd like to build it in to my home made set-up to avoid over discharging the pack and potentially reversing the polarity of the cells. Any advice on what's been used, or what the appropriate type of device would be would be greatly appreciated.

    Thanks,
    Mark
    Have a look at the MC33164 or MC34064 swiching a mosfet like an IRFZ44N. I've used these on 6, 13.2 and 14.4V systems. You just need to monkey around with a resistor divider until you get the cutout right.

    Good luck
    GEVELTERSCHMIDT RACING

  3. #3
    Gone riding
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    That’s probably one of the better ways to go about it.

    I have also used the Maxim MAX8211 Programmable Voltage Detector to build a visual warning device rather then cutting the power to your light. It’s easily built with a single capacitor for filtering, and a few resistors to form a voltage divider, which the chip uses to compare against a self generated precision reference voltage. You can rig it up to turn an LED on or off when the battery voltage drops past a certain point, set with the voltage divider.

    Dave.

  4. #4
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    Airman / Low_Rider,

    Thanks for the info. Any suggestions for on-line retailers for these parts? I looked at a couple, but they seem to have pretty high minimum order amounts or qty's.

    Thanks again for the info.

    Mark

  5. #5
    ballbuster
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    Here's your ticket

    I bought the dual head controller, but they make one for a single lamp as well. It has a low voltage warning and cuttoff as well.

    THey even have a DIY instructions and software to download in the EPROM if you wanna build it from scratch yourself.

    http://www.trailheadlights.com/

    best controllers ever. I love mine. Tap the button for brighter light, hold it down to dim it. When all the way dim, hold for 2 seconds to turn it off.



    DIY instructions here:

    http://www.lasertagparts.com/lightbrain/2002_twin.htm

    Last edited by pimpbot; 11-04-2006 at 12:08 PM.

  6. #6
    some kind of hero...
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    Quote Originally Posted by gubawatts
    Airman / Low_Rider,

    Thanks for the info. Any suggestions for on-line retailers for these parts? I looked at a couple, but they seem to have pretty high minimum order amounts or qty's.

    Thanks again for the info.

    Mark
    Its hard to beat pimbot's suggestion . That wouldn't work for me because I built for HID and LED systems. The trailhead one is for halogens only...

    I've used Digikey and Mouser for electronic parts I can't get locally, but most of what I build is based on what my local supplier can provide. I build because its something I like to do, not because it is cheap ... Sometimes it even works better that what the big guys sell.

    Good luck
    GEVELTERSCHMIDT RACING

  7. #7
    Gone riding
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    Hi Mark, I have sent you a PM regarding small quantity orders.

    I built a couple of PWM dimmers loosely based on the Light Brain open source design a number of years ago. I used SMD components on the back of the board to keep the size down, but unfortunately I was limited to a pretty large Microcontroller at the time. I really should do a re-design and implement a few more features in a smaller package. I’m not really playing with Halogen stuff anymore though.

    Dave.


    Last edited by Low_Rider; 11-04-2006 at 09:29 PM.

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