battery & solar powered weather-station with Pi Zero: some musings about the mileage - or: How long would the battery last without?

thedighubs

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Nov 21, 2024
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dear community - hello and good evening.


A battery and solar powered weather-station with Raspberry Pi Zero: some musings about the mileage. or:
How long would the battery last without sun, a quick estimation:


i am interested in understanding the power needs of a specific Raspberry Pi model and choosing the right power supply,
ensuring a more stable and reliable experience with your Raspberry Pi projects.


i am loving Battery-Powered Raspberry Pi Projects: Taking Raspberry Pi projects off the grid and making them portable is a great thing - in other words it
opens a world of great options and many possibilities, from outdoor environmental monitoring systems to many many others.


therefore choosind batteries as a power source is key to this mobility, but it requires good planing.
and especially - if we charge the battery with solar. I am planning to do so:

my project: i use pi zero. some preliminare calculations.:

Pi Zero draws 0.5 watts. That was with the LED and WiFi disabled.

well i am currently tring to get a bigger picture:

my question is:
How much current is that? 0.5 Watts / 5 Volts = 0.1 Amps = 100 mAmp.
20,000 mAmpHours / 100 mAmp = 200 Hours = 8,33 Days!

With WiFi, we are down to 120 mA (0.7W) = 166.7 Hours = 6.9 Days.

question - is thie a accurate calculation: or should i probably divide the Wh of the battery by the watts of the pi
(that would then make the bold assumption of 0 losses to converting 3.7V to 5V among other inefficiencies).

i guess that the "total" efficiencies can range from the upper 80% to the lower 70%. that said: Battery mAH from sales may differ for real measured mAH.
conclude: The only way to know it to test it.

look forward to hear from you