E switch question

Is it possible for an e switch to use less current when closed than it’s parasitic drain when open? I don’t really understand parasitic drain. Does it only exist when the switch is open?
What makes me curious about this is my TN4 which rarely gets used these days. Twice now I have went to it only to find it dead. What puzzles me is that at one point I turned it on in moonlight and left it on for something in the ballpark of 3 months. Nearly certain that it has went flat while turned off faster than when turned on in moonlight. Does this make sense?

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Are you asking why an electronic switch has parasitic drain while the mechanical switch doesn’t?

I think the question is whether a light with an e-switch uses more power when off and waiting for a click than it does when turned on and in moonlight. I would say no to moonlight using less than when off. But one would have to do a careful test IMO

Yea that is the question. I would think no as well but it sure seems like my experience would say otherwise. I just wonder if the pathway for parasitic drain might be eliminated when the switch is on and therefore if the load of moonlight is less than the load of the switch waiting for a signal it would explain why it could stay on for a longer period than it can stay off. OTOH, it is quite possible that more time elapsed than I realized when the light was off.

That is why I would do an actual timed recorded test. I can’t trust my “seat-of-the-pants” so much any more.

I’ve measured the power use of a bunch of e-switch lights. Typically the results look something like this:

  • On, in moon mode: 1.5mA to 6mA
  • Off, with aux LEDs on high: 0.5 mA to 8 mA
  • Off, with aux LEDs on low: 0.05 mA to 0.10 mA
  • Off, with aux LEDs off: 0.03 mA
  • Off, with no aux LEDs and no sleep timer: 0.02 mA
  • Off, like above but with no brownout detection (BOD): 0.002 mA

The amount of power used by an e-switch is basically zero. The amount of power used by the MCU in standby mode, however, is generally around 0.02 to 0.03 mA. That’s where most of the parasitic drain comes from.

The battery’s self-discharge rate matters too. It’s often higher than the MCU’s parasitic drain, but I don’t have good measurements of that.

… and if you have any LEDs on, it uses a lot more power. Generally anywhere from 5X to 200X more power. Keeping it in moon mode (instead of off) cuts the standby time from like 4 years to 2 months.

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