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Reply To: Battery Measurement accuracy

Home Forums Mayfly Data Logger Battery Measurement accuracy Reply To: Battery Measurement accuracy

#14667
neilh
Participant

So just to add some more characterization measurements.

I’m using a Mayfly Sn 20395, and attempting to characterize what range the readings from the Mayfly ADC Vbat are linear when it is only powered from Vbat.  I’ve put a resistor network on the extV to the LiIon batter, to halve the voltage to keep it within the Vcc range for the ADS1115. Initially I used 100K//100K – and verified the output is linear.

I’ve connected an external  powersupply to the Vbat, an external Meter (Materman 37XR) and then making measurements

Power supply to Mayfly JP1 Vbat (instead of LiIon)
Adjust power supply voltage to desired V measured on Meter.

My conclusion is that the Mayfly Vbat becomes nonlinear under 4.0V.

TimeStamp Meter extVbat adcVbat
12:28:00 4.225 4.208 4.291
12:30:00 4.103 4.090 4.139
12:32:00 4.106 4.092 4.139
12:34:00 4.00 3.989 3.957
12:36:00 3.90 3.889 3.760
12:38:00 3.80 3.793 3.563
(break)
13:22:00 3.79 3.794 3.578
13:24:00 3.70 3.691 3.517