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--- projects:blinker:work_logs:6_power_consumption_testing [2022/03/06 23:00] – tjhowse
+++ projects:blinker:work_logs:6_power_consumption_testing [2022/03/07 04:39] – tjhowse
@@ Line 67: / Line 67: @@
 These tests gave me a good idea of what the runtime of the final device will be. They also confirmed that the power consumption of the microcontroller and LED is less than the leakage across the Zener, but more than the self-discharge of the supercaps. The result is that I can scale up the number of supercaps and be confident that the runtime will increase more or less linearly.
+<code>
+def calcEnergy(farads, deltaVolts):
+    return (farads/2)*pow(deltaVolts, 2)
+</code>
+With 25 Farads capacity, and a deltaVolts of 0.75v (started at 2.25v, ended at 1.5v), we get a stored energy of 7 joules.
+<code>
+def calcWatts(joules, seconds):
+    return joules/seconds
+</code>
+Over 30000 seconds we get 233µW. At an average of 1.875V that gives us 124µA. The rated leakage current of the Zener is 120µA at 1v, so this seems reasonable. Once the full compliment of six 40-Farad caps are installed we should get a runtime of around 6 days. These numbers are all very rough, and treat a pretty non-linear curve as linear, but they should be approximately close.
 ===== Video =====