Page 1 of 2 1 2 LastLast
Results 1 to 25 of 45
  1. #1
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278

    7UP Cutter/Troutie 1000ma trouble

    I need to draw on the collective wisdom of the light gurus.

    I got the light through Cutter, was not confident of assembling it myself so contacted a light builder who put it together for me. He also sent me some old Li-Io14.8v 4.4Ah Tenergy batteries to get me going.

    Light works, and I had it set on 5 levels of output. After reading the threads on others 7Up's I set max current draw at 1000ma. When running the light on level 5 (Max) it runs for about 2 mins then cuts off. Not completely dead but just the faintest of faintest glows coming from the LED's. On level 4 output it would run for almost 2 hours.

    I tried both batteries for pretty much the same results. I had the light set up with a large pedestal fan blowing on high. Housing temp reached 38c (using and infrared thermometer) and sat there.

    I contacted another light/battery builder local to me about trying a new battery to see if it was the old batteries causing the problem. He had a new 5AH LiPo and we tested it for the same result, shutdown around 2 minutes. We then set the thermal cut off at different temps for no difference.

    Has anyone else had this problem when running at 1000ma?
    blah blah blah

  2. #2
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    420
    I am no expert but I found on mine, the temp sensor was set lower than my needs and by adjusting this upwards, I have found for me that this was a better solution.. also the housing temp is not the same as the internal temp and this can be misleading..

  3. #3
    Rep Power Infinity +2
    Reputation: brad72's Avatar
    Join Date
    Jun 2009
    Posts
    1,567
    Aslo don't forget that the infrared thermometers are very inaccurate if the surface you are trying to measure is glossy. A matt surface will give you a far more accurate result, but of course the alloy directly underneath the temp sensing IC chip on your driver will be hotter compared to the rest of the housing.

  4. #4
    mtbr member
    Reputation: troutie-mtb's Avatar
    Join Date
    Sep 2007
    Posts
    3,053
    Have you had a look inside to see if the maxflex is installed correctly on the heat sink
    with good thermal epoxy

  5. #5
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Pulled the back off and had a look inside. All looked neat and secure.
    Attached Thumbnails Attached Thumbnails 7UP Cutter/Troutie 1000ma trouble-7up-1.jpg  

    7UP Cutter/Troutie 1000ma trouble-7up-2.jpg  

    blah blah blah

  6. #6
    mtbr member
    Reputation: troutie-mtb's Avatar
    Join Date
    Sep 2007
    Posts
    3,053
    Good pictures there

    I am thinking the maxflex is positioned wrong too far over to the left.

    the Vias through to the chip that needs cooling are missing the heat sink
    it look like it needs to be removed and repositioned
    the R4 resistor I put in the centre of the tab maybe even slightly to the right of centre.


  7. #7
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Thanks Troutie, will give it a try and see what happens.
    blah blah blah

  8. #8
    mtbr member
    Reputation: znomit's Avatar
    Join Date
    Dec 2007
    Posts
    1,688
    Mom switch leads are enormous!
    DIY LED Bike Lights:
    A few Dynamo builds and some Small battery lights

  9. #9
    mtbr member
    Reputation:
    Join Date
    May 2010
    Posts
    31
    Quote Originally Posted by EFMax
    I am no expert but I found on mine, the temp sensor was set lower than my needs and by adjusting this upwards, I have found for me that this was a better solution.. also the housing temp is not the same as the internal temp and this can be misleading..

    what would you recommend setting the temperature to? i have it on lowest temp, but cause im just commuter riding at the moment and i dont want to blind cars coming in opposite direction im not running it flat out.

  10. #10
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Anyone else got an internal pic of a perfectly working light they can post that shows the maxflex position?
    blah blah blah

  11. #11
    mtbr member
    Reputation: zen bicycle's Avatar
    Join Date
    Mar 2007
    Posts
    452
    I'm with trout, it is missing the heat sink. Detatch clean and move it over a bit to the right. It sounds like the IC switcher(I think that is right) is overheating causing the board to shut down.

    A good test of this is to try a slightly higher battery voltage and see if it does the same thing. Like an 18 volt pack. If it doesn't shut down with the 18 volt pack then the board positioning is the issue.

  12. #12
    mtbr member
    Reputation: troutie-mtb's Avatar
    Join Date
    Sep 2007
    Posts
    3,053
    Here is what I do

    warm the housing with a hair dryer ( I am in the UK in a cold garage )
    Keep the hairdryer handy for later .

    mark the centre of the tab with a pen so you can line up the R4 resistor when the glue is there .

    a small blob of each part of the AA on to the tab to mix it less waste that way I use a small round file so I can work it into the tab nicely
    then work some into the gold pad on the Maxflex even into the vias

    position the maxflex with your centre mark and apply pressure to hold it in place while the glue sets

    use the hairdryer to warm the housing and set the epoxy quicker

    dont be stingy with the glue too much is better than too little as it squidges out and you still get a nice thin bond layer with the warm case the extra that squidges out helps also



    And when you wanrt to remove the maxflex warm the housing to nearly too hot to touch and the epoxy will let go easier

  13. #13
    mtbr member
    Reputation: heatstroke's Avatar
    Join Date
    Jul 2003
    Posts
    1,009
    I think your issue is with ". old Li-Io14.8v 4.4Ah Tenergy batteries"
    Question :
    Were the batteries freshly charged ?
    I measure about 0.7V sag on a new freshly charged 1.4V battery pack , driving the LEDS at 0.7A drive. I am pulling 1.16A off the battery pack (4s1p pack)

    Have you measured your battery pack voltage ? under load ?

  14. #14
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Quote Originally Posted by heatstroke
    I think your issue is with ". old Li-Io14.8v 4.4Ah Tenergy batteries"
    Question :
    Were the batteries freshly charged ?
    I measure about 0.7V sag on a new freshly charged 1.4V battery pack , driving the LEDS at 0.7A drive. I am pulling 1.16A off the battery pack (4s1p pack)

    Have you measured your battery pack voltage ? under load ?

    Also tested it with a brand new 5ah lipo 14.8v battery for the same result.
    blah blah blah

  15. #15
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    I have been away on vacation and only just got back. Instead of unpacking I decided to do some more testing with the light (wife not happy LOL). I have the light sitting on the kitchen bench with the handle bar mount clamped to the plastic handle of a sharpening steele. I have a pedestal fan that we use in summer in the kids room at night sitting about 20cm in front of the light blowing directly on to the front of the light.

    I tried a fresh charged 14.4v pack and I also used the 18.something volt pack that I have. When fully charged it sits around 21v, so I ran it with the other light for about 45min to drop the voltage down to about 19.8v before connecting to the 7UP.

    I set the temp cut off at 80c, and 1000ma current draw max.

    The 18v pack first, it ran for 30 minutes on high with no problems. I shut it off as it was working perfectly, (and the wife was nagging to help unpack) I also tested amp draw and it was 1.42 amps

    I then let the light cool back down to room temp (20c)

    I then tried the 14.4v pack, it ran for 3min 4sec before shutting down completely to the ultra low flickering glow. I also tested amp draw at 1.81amps.

    I let the light head cool again to room temp.

    I then re did the test on the 18v pack but set the temp cut off at 70c. The light ran for 4min 40sec and dropped to L3 and continued to run. I then shut it off. I did not bother to do the test with the 14.4v pack at 70c as I did not see any point.


    Thoughts?
    blah blah blah

  16. #16
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Quote Originally Posted by zen bicycle
    A good test of this is to try a slightly higher battery voltage and see if it does the same thing. Like an 18 volt pack. If it doesn't shut down with the 18 volt pack then the board positioning is the issue.

    My latest tests seem to confirm this.

    I managed to get my hands on another maxflex just to have a look at the thermal pad on the back and compare its position to the one in my light. To me it looks like the pad is mounted almost exactly inline with the heatsink in the housing. But from what I'm reading is that its the 3 resistors doo-hickeys(Lol) that need to be centered on the housings heat sink.
    blah blah blah

  17. #17
    mtbr member
    Reputation:
    Join Date
    Apr 2008
    Posts
    105
    The flickering is the symptom you get when the switcher chip overheats. At the lower voltage the driver is less efficent and hence the switcher chip heats up more. The thermal protection is not normaly getting a chance to act the switcher chip heats up too quick for the microcontroller which measures the tempreture to get to the tempreture you have set. You need better heatsincing to the switcher chip.

  18. #18
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    287
    Ifor is correct. The temperature settings in the uC pertain to the what the uC can measure - internally.

    With a poor thermal path, the junction temperature of the switcher IC will reach the point where the IC fails (that's the turning off / flickering you are seeing - you WILL destroy the chip if you continue to let it reach that failure point).

    The thermal path you have will keep the board cool enough that the uC will not sense overheating and so it doesn't roll the current back to L3 - in the meantime the switcher IC is cooking inside.

    There are pictures of the thermal pad area and what I think is a good document on the thermal problems that can occur at www.taskled.com/techmaxflex.html.

    You NEED to improve your thermal path or you WILL destroy the switcher IC. The turning off and flickering is a FAILURE condition of the switcher when it overheats. The switcher does NOT have internal thermal protection. Pushing it to that failure mode multiple times will cause the magic smoke to escape...

    The thermal path from the switch IC is the 20 microvias you see in the picture in the tech section. That whole area of 20 microvias MUST be in contact (via a THIN/UNIFORM layer of thermal epoxy) with the heatsink. If as Troutie writes, you have that area not entirely (or at all) sitting over the aluminium pedestal of the housing then you do not have a good thermal path.

    You are trying to push around 3.4V x 1A x 7 = 24Watts through the maxflex driver - that's a heck of a lot of power. maxflex can do it - but the thermal path must be perfect. Even a small air pocket in the thermal epoxy (if not applied well) will cause you problems.

    cheers,
    george.

  19. #19
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    420
    Quote Originally Posted by nexus666
    what would you recommend setting the temperature to? i have it on lowest temp, but cause im just commuter riding at the moment and i dont want to blind cars coming in opposite direction im not running it flat out.
    I have mine set up at its highest point which I think is about 80 or 90.. I need to know that when I am out and about nowhere that the lights will not let me down by switching down or off as it is a bit of a shock to you when it happens..

    Even if the temp setting is high, the light setting can still be low and thus avoid dazzling others when commuting.

  20. #20
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    287
    I'll just reinforce my previous post in this thread one last time...

    1) Maxflex will NOT turn off if the thermal monitoring kicks in - it will only dim to L3.
    2) If maxflex does turn off due to over temperature - this is the switcher IC FAILING.You need to resolve this to prevent permanent damage to the switcher IC.
    3) if maxflex is dimming to L3 due to the uC tripping on the set temperature value you likely are a) not moving (housing is overheating due to lack of airflow) or b) your housing has insufficient thermal dissipation capability or c) you set the temperature trip point too low.

    For 3a) and 3b) maxflex is saving your LEDs/Driver from destruction.

    For 3c) you can increase the temperature trip point - BUT please be conservative in your settings unless you have measured actual housing/LED and maxflex switcher temperatures to know you are within safe operating temperature ranges.

    Just because you can crank up the output current of the driver, doesn't mean you should. This is the key difference between a DIY and a Commercial light. In the case of DIY all the operating parameters are YOUR responsibility to set to safe levels whereas the Commercial light has already (assuming a well designed/supported light company made the product) been set to safe levels.

    cheers,
    george.

  21. #21
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Thanks for the info George.

    I heated the housing up and have removed the maxflex from the housing. It was a thin layer bonding it together. It looked like the pad on the maxflex was sitting right on the housings tab.

    By moving it over as suggested, so the 3 resistors are over the center of the tab will mean the maxflex pad is not sitting entirely on the housing tab. I just want to confirm that's the right position before I stick it down again.
    blah blah blah

  22. #22
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    287
    The 20 microvias MUST be totally on the heatsink pedestal.

    cheers,
    george.

  23. #23
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    George, what exactly is the 20 microvias? Is that the entire gold pad?
    blah blah blah

  24. #24
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    287
    As per PM - it's the 4 x 4 grid of holes in the rectangular gold area. Those vias are a direct path from the thermal pad of the switcher IC on the other side of the PCB.

    cheers,
    george.

  25. #25
    what a joke
    Reputation: ozlongboarder's Avatar
    Join Date
    Jan 2004
    Posts
    2,278
    Thanks for the help George.
    blah blah blah

Page 1 of 2 1 2 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •