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« on: June 06, 2020, 1742 UTC »
Yeah, I agree with CDS.... I'd be leery of anything like conformal coating. It's a major PITA to deal with afterwards, it's rarely as inert as advertised and it's a rework/repair nightmare. I think it's more meant to avoid condensation and dirt in industrial electronics rather than actual waterproofing. Find an ammo box, or a plastic snap on container or the like to waterproof your electronics. There's lots of solutions for short money. The crappy part is, most waterproof containers are almost impossible to glue to when you need to.
I'd also consider putting more hysteresis in your undervoltage logic. If Vbattery is low, I'd sleep for an hour or so to get the voltage >> your threshold of concern voltage. I'm thinking you want to stay further away from brownout conditions than the 8 sec tolerance.
Just my inexpert 0.02$!
** Edit- was looking at ATTiny specs last night and it looks like one can get the standby current in "sleep" mode down to the uA range! I have some dev boards I'm going to play with for some keying functions. I think there's 5 I/O's on those boards too.
Fun project!