Re: Powering that QCX: DC-DC Converters


Hi Dave,
I was concerned that using a DC-DC converter in my QCX power circuit might generate an EMI headache, so I built a setup to run my QCX on battery power.  I use 4 18650 Li-ion cells.  This is a rare situation where I have brand loyalty.  I have bought many unbranded 18650 cells on ebay and found that every time the actual capacity is far less than the seller claimed.  Then I tried batteries from Tenergy; they lived up to the capacity claims.  Other well-known brands are probably also good.  I bought holders for these so that I can remove them for individual charging.  The holders are mounted to one side of a piece of acrylic; the QCX mounts on the other side, making a compact setup.  I rigged a toggle switch and diode to drop 0.6 V to prevent the pack's output voltage from exceeding the QCX limit when the batteries are fully charged.  After several minutes, I close the switch, shorting the diode.  I calculate that one set of batteries will last me several hours; far more than I need for a day-hike SOTA session.  So, next time I might make a similar setup using smaller (14500) Li-ion cells to reduce mass.
Halden VE7UTS

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