Case Analyzer and USB Charge Rate

[LeeWB3]

I am attempting to run the case analyzer on a DNA 75 that was not calibrated by the manufacturer.  I do know what I'm doing.

I cooled the mod to room temperature overnight, hooked it to the computer and started the case analyzer quite quickly to minimize charging temp change.  The mod reached back to ambient temperature in the 30 minutes it allows and then started charging.  All normal and as expected.

When the mod started charging the top portion of the case analyzer dialog box reported that it was charging at 0.4A.  However the graph portion showed that it was charging at 0.240A.

I have a very late model, custom built PC that I am sure is capable of outputting the USB 2.0 standard of 0.5A (actually, 0.495A per escribe device monitor).

Is the latest Service Pack (1.2SP5) incorrectly telling my computer to only charge at 0.240A or is it misreporting that it is supposed to be charging at 0.4A when it is actually trying to charge at 0.240A?

This discrepancy would HAVE to throw off the degF/A calculation unless one of those two numbers were wrong.

[KISS V.]

Bill, I too have seen this in my last run of a calibration, I didn't put it together. I am interested in knowing the solution and possible results.

[Spector NS5 RD]

quick answer.....on the DNA 75, the MCU cannot fully communicate with the simple linear charging IC. as in, the MCU cannot ask for a specific charge rate from the charging IC, there is no read back. whereas, the DNA 200/250 can ask for specific charge rates because of the complex charging circuitry. Evolv got it as close as they could regarding charge currents for case analyzer with the 75 board. the discrepancy you're seeing will not effect the end result of the test, by much at all. at least you'll have values input for CA now, whereas the manufacturer did not. hope this helps.

[KISS V.]

Thank you

[LeeWB3]

Thank you for the information.

I'd kinda assume that the test measured the temperature change observed and divided by the expected charging rate of 0.4A.  The results of the test for that mod was reported as 19.24 degF/A, so, assuming it's doing what I think it's doing, that would imply it actually saw an increase of 7.696 degF  (19.24 degF/A * 0.4A).  It would seem to me to be more accurate to override the calculated value and use the temperature change of 7.696 divided by the actual reported input current of 0.260A to find a degF/A of 29.6 degF/A.

Since the manufacturer did not provide values, I'd agree the 19.24 degF/A is likely better than Evolv default values.  However, would it it not be even better to manually input the 29.6 degF/A as calculated above?