WEBVTT


NOTE Transcript 2024-04-11 from FLAC by https://elvery.net/prototypes/transcribe/ on my MacBook Air M1 on maximum quality setting.
NOTE Body edited.


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Hi, I'm Damon Hart-Davis and this is a quick bonus Earth Notes podcast episode for 13th


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October 2019.


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Following on from the random sounds, I decided to "audify" some battery data.


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Enjoy!


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I used the same techniques, including sampling faster than needed and using Audacity to get


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down to 44.1 kHz, normalised then resample, and thus one year per second.


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The same strong daily 365 Hz tone is in there, a little buzzy as usual because the data is


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messy real life and not a perfect sine wave.


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Each of the datasets turned into audio here runs from early August 2018 when the Enphase


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was installed through to the end of September 2019, so each track is just over one second


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in length.


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First, I tried listening to how full the Enphase AC battery was, also known as its state


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of charge (SoC).


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Because this changes relatively smoothly, this one is not very buzzy.


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It is quieter in winter when the battery often doesn't get a full charge for example.


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Then I tried listening to how the battery charges, which is being driven from my large PV array, so fairly abruptly goes from nothing to full on and back again most days.
It does follow the sun in regularity, but charging is sometimes interrupted when we


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turn on a big load such as the kettle or oven.
Like all of them, this has a seasonal element to it. 


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Next up is discharging, which is more random and buzzy depending on when we run appliances.
The fridge/freezer's regular demands for 80W half the time are in there somewhere.


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Then in Audacity, I shoved charging into the left channel and discharging into the right.


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The stereo hints at something interesting.
Finally, and very seasonally, is the PV generation as measured by the Enphase. Even this is more noisy than you might expect, as sunshine is significantly intermittent


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in the UK.


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There's more on my Earth Notes Web site at Earth.Org.UK.