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A project log for Sol BLE Tracker

Solar powered Bluetooth Low Energy Tracker with beeper and LED to assist in locating it.

dryerziniaDrYerzinia 08/11/2015 at 08:290 Comments

The power supply section of the revision 5 board of the Sol BLE Tracker is built. And of course its time to test how much charge current I get. In these tests its drawing all the quiescent current it would normally minus the 1.6 uA of the BLE radio.

Revision 5 minus the radio.

Above you can see the by the window couch test. 992 lux on a sunny day providing 76uA of charge current. 7x more than enough to run the system.

The readings from the real world tests are not a nice strait line and I suspect this is because of how much the angle of incidence affects the lux meter on my Galaxy S6 Active but we can still draw some useful conclusions from it. The main thing to take away is that on a sunny day in the open areas of the house the ambient light is going to be enough to charge the system. Also if the cats spend just a few minutes a day in direct sunlight it will have no problem running forever without having to attach an external charger.

In the data for the microscope light test you can see a small jump where it also changes slope. That was where I moved the light physically closer rather than varying the input voltage to get a higher lux reading. The first set of sets showed a slope of 25 lux/uA. The second set 42/uA. The main takeaway here is we should expect to need 300+ lux to run the system. With a proper lux meter the real world measurements would likely match this figure as the angle of incidence problem would be solved. I expect this test to be fairly accurate as all the light is coming from one direction however the LED spectrum is not the same as sunlight.

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