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ErgoBlue 2 Solar Battery Life

Whether the solar panels will receive enough energy to maintain the battery level depends on a lot of factors such as how close you are to the window and how much sunlight your area receives.

I generally use my keyboard at my desk away from direct sunlight so the power that is achieved is significantly less than what the solar panels can capture in optimal conditions. In my particular environment for example, two SM141K04LV panels can provide between 400uAh-1000uAh per day depending on the weather by a crude estimate.

Here is a graph of the battery voltage for the last 500 hours of operation. In my environment, solar is enough to maintain the battery voltage and never having to charge.

Large Battery Graph

For comparison, 2.7V is around 100% and 2.3V is around 0%. Do keep in mind that the battery discharge curve is closer to cubic than linear .

Small Battery Graph

When running my firmware alongside ZMK, the Nordic nRF52840 Dongle uses around 1000uAh per day whereas the Fanstel nRF52810 around 400uAh per day (shown above). The group buy variant will likely use around 400uAh per day. A different firmware or a different setup will likely achieve somewhere between a slightly worse to a significantly worse battery life.

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