Recent content by Tobias Bossert

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  1. Tobias Bossert

    Driving an LED on a Primary CR123

    Re: Driving an XP-L on a Primary CR123 None of them will work for your project! The voltage of primary CR123 is below the voltage needed to drive cree XP-L at reasonable power. If you are fixed on a single primary CR123, you will need a buck-boost driver. But on the other hand there is a...
  2. Tobias Bossert

    Qlite Rev.A 7135*8 Multiple Modes Circuit Board 3.04A

    I guess the problem comes from capacitor C1, which may be far to small to supress voltage sag during on stage of pwm. Try with a much bigger one with low esr and I predict the behaviour will change to "normal".
  3. Tobias Bossert

    Maintaining Charge When Storing Li-ion Cells Long Term

    Nice: That's exactly the reason why I proposed to use the battery comparator, covering a wide varity of batteries. HKJ conducted measurements for a small count of batteries only to estimate remaning capacity in LiIon batteries. So, if you can find there your type exactly, use it. If not, go back...
  4. Tobias Bossert

    Maintaining Charge When Storing Li-ion Cells Long Term

    Sorry, it is not possible to define voltages valid for all Li-Ion chemistries. Usually you should target a charge of about 50% of capacity and allow a window from minimum 20 to maximum 80%. The open loop voltage at 50% of charge depends upon the chemistry of the cell: Panasonic NCR18650B: 50%...
  5. Tobias Bossert

    Review of charger Soshine SC-S1max V3

    Warning The chargers Soshine SC-S1max V3.0 actually sold by DealExtreme are NOT the same as tested here! They always skip the stage "green flash - 90% complete" but immediately switch to "green - complete". They still provide pure DC modes CC/CV but never stop CV mode: There is no current...
  6. Tobias Bossert

    Test/Review of Charger Soshine S1 max V3

    Warning The chargers Soshine SC-S1max V3.0 actually sold by DealExtreme are NOT the same as tested here! They always skip the stage "green flash - 90% complete" but immediately switch to "green - complete". They still provide pure DC modes CC/CV but never stop CV mode: There is no current...
  7. Tobias Bossert

    4.35V cells - Should different voltage limits be used on them (vs 4.2V cells)?

    Yes, neither you should discharge them down so far as "normal" cells, nor you should store them at open circuit voltages of about 3.6 to 3.7V I use those cells (especially LG ICR18650D1 and E1) in a helmet lamp project with single cell supply and linear driver for LED currents up to 3A. For such...
  8. Tobias Bossert

    Recommended battery amperage for high drain lights?

    The anwer to the question of this thread depends not on the current capability of the cell only, but on the driver technology too. Linear driver: The battery voltage under load should stay above the forward voltage of the led plus about 0.1V. For example an XM-L2 driven at I=3A has Vf=3,4V. So...
  9. Tobias Bossert

    Lower drain Li-ion battery actually BETTER for some lights?

    This is not true under all circumstances! Yes, a lower internal impedance of the battery reduces the voltage sag under load. But the acceptable voltage sag also depends upon the differenve between forward voltage of the LED and the open loop voltage of the battery. Some "older" ICR have a much...
  10. Tobias Bossert

    Continuous vs intermittent discharge

    The voltage sag under load depends upon duration of pulse, as can be seen in diagram 2. When the discharge pulse starts, the voltage sags instantaneously. During the pulse it further sags contiuously. After the discharge pulse has terminated the voltage jumps back instantaneously but needs some...
  11. Tobias Bossert

    Internal Impedance Measurement Sharing - Lots of Batteries

    It highly depends upon your application, which kind of impedance measurement you will need to estimate the real behaviour during discharge of a battery. Most applications will not be approximated by any AC tests. If you need low AC impedance you will use a capacitor as near as possible at the...
  12. Tobias Bossert

    KeepPower 18650 3200mah (new Panasonic NCR18650BE cell) quick review

    In the thread 'continuous vs. intermittent discharge' I tested Panasonic NCR18650 B, BD and BE under harsh conditions. Post #11 summaries the findings. B has a little bit higher capacity at low discharge rates but shows a higher internal resistance. BD and BE hold voltage at 3A discharge current...
  13. Tobias Bossert

    Confused about boost driver...

    The output power is 12V*0,3A=3,6W If the boost driver has an efficiency of 70% when converting from 3 .. 3,7V to 12V, than the input power will be 3,6W/0,7=5,1W Modern 18650 cells deliver about 10Wh and the rough run time will be about 2h When the battery is nearly fully charged the voltage may...
  14. Tobias Bossert

    Continuous vs intermittent discharge

    Re: Added: Panasonic NCR18650BD and BE I measured a grey NCR18650BD and a lime green NCR18650BE from Panasonic now (both are unprotected). Both show curvatures quite similar to the lime green unprotected NCR18650B. Under load BD and BE hold voltage slightly better due to lower internal...
  15. Tobias Bossert

    Continuous vs intermittent discharge

    Re: Added: Panasonic NCR18650 B Unfortunately this new cell 'MJ1' will be 4,20V only. Nevertheless it will be a verry interesting cell, I guess.
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