An update on measuring battery voltage. I’ve purchased a number of Mayfly1.1 for a project. And on testing one of this batch, the noise level of measuring LiPo is better – which is great. The noise level of resistors is part of their specification, or it might be just luck in this case. Often a batch of noisy resistors is because the manufacture has selected out the low noise resistors.
The testing is at my office desk – which as I am finding out, is also electrically a noisy environment.
For release testing I’ve moved it to an outside environment and the noise level is even better, which is soooo nice.
Here is the graph of the lower noise measurement, where there is a cutoff of transmitting data at LiPo=3.8V (measured from A6 Blue line) with a more accurate 12bit measurement (black line).
This is 4 days of testing, with accelerated 2min readings and if the LiPo V was above 3.8V immediately transmitted to MMW. When it dropped below 3.8V it queued the readings. Then when the solar came back, charged the battery and the readings went up 3.8V, it transmitted the data. The black line is the more accurate 12bit reading, which in this specific Mayfly the blue line A6 is fairly accurate.