@BMitch That's indeed an advantage of non-latching solenoids.

If you want to have a battery-powered valve controller controller, the power which a non-latching solenoid requires to stay open become non-trivial.

@NickAlexeev Most of the controllers I've seen for home sprinkler systems are powered off the mains.

And by most, I've never seen a battery powered one, not that I've seen many.

I did a quick calculation for the following operational profile: water for 30 minutes 3 times a week (Phoenix AZ proifile). It turned out that it would take 75 alkaline AA cells to operate like that for 6 months. That's a lot of cells.

If you're doing a hobby project, they make mechanical shutoff valves that are water powered. Turn a dial for how much water you want and it shuts off after so many gallons. You could theoretically attach a motor/servo to crank the dial and then not need any power to let it run and shutoff.

But I'd just get a standard sprinkler system and wire it to the mains like normal. Hobby projects often cost more than they save, and anyone buying the home would insist on having it replaced with something standard as part of the sale.

@BMitch Big warehouse stores don't carry battery powered ones. But they exist. They run latching solenoid valves. The probably solve the power issue with careful battery management.

Good luck, I'm off for the night. o/

@BMitch This is a homework assignment for an interview. The company I'm interviewing with isn't in the sprinkler business.