Re: ESP32 wireless SHC (wSHC)


Dave Schwartz
 

Testing with the wSHC with a dimmed display (so the background command polling interval was 1500ms instead of 300ms) gave a battery life of 12 hours and 15 minutes. At that point the unit rebooted and I turned it off immediately.

This should be enough for an entire night's observing. Intervals when the unit is consuming more because it is at the status screen and not dimmed should be more than compensated by times when the unit is idle and the display blanks (at which time the polling interval drops to 10s as a keep-alive) so the battery life should be even longer. This test was at room temperature so YMMV if you observe in colder weather lifetime may be reduced (Energizer's Ni-MH and alkaline batteries lose 25% capacity at 0C and 75% at -20C, Li-ion is much better [ref https://data.energizer.com/pdfs/temperat.pdf] so you may want to keep your wSHC in your pocket).

P.S. When the battery voltage was measured at the end of the test, the cells were all very close to 1.15V so this indicates that the ESP32 begins to have problems at 4.6V. This would explain the need for a good quality cable on a wired SHC to avoid stability problems because its quite easy to drop 0.4V across a 2 meter, small gauge wire. It may be possible to compensate a bit by raising the main regulator voltage a couple of tenths of a volt (if the controller design has an adjustable regulator e.g. the STM32 Blue Pill) but I'd try the 'better cable' approach first.

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