Battery testing, part 2

Following up on my previous post, here is some more data:

I finally got one data set without interruptions or loss of data; 49 hours of continuous receive by the (tr)uSDX, from an initial 12.36 volts to shutdown at 9.40 volts. The Watt’s Up meter indicated 2.968 amp-hours, 31.2 watt-hours.

I made this little thing to allow inserting a DMM inline to check the current measurement calibration of the Watt’s Up.

Now here we have a problem: the Watt’s Up is not accurate! For an indication that flickers intermittently between (mostly) .06, sometimes .07, I read:

  • on the Fluke 25, 74.7 mA
  • on the Fluke 75 III, 74.2 mA

That’s a big enough difference to make a noticeable skew in the test results; I’ll have to work the math to make a correction factor to apply. (mumble mumble)

Oh well, that’s all for now; there will be more later.

Thanks for visiting driftlessqrp!


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