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--- projects:blinker:work_logs:6_power_consumption_testing [2022/03/06 22:57] – tjhowse
+++ projects:blinker:work_logs:6_power_consumption_testing [2022/03/07 04:38] – 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 =====
@@ Line 76: / Line 90: @@
 ===== Next Time =====
-I don't think there's much point in trying to further improve energy efficiency of the code. The next steps might be adding features like multiple message sequences, and/or improving the space efficiency to fit more/longer messages.
+I don't think there's much point in trying to further improve energy efficiency of the code. The next steps might be adding features like multiple message sequences, and/or improving the space efficiency to fit more/longer messages. I may investigate alternative means of regulating the voltage from the solar cells. I need to find a replacement Zener, as JLC seems to have disappeared the one I used for the first batch of PCBs.
 [<6>]