Sprinkler Valve electrical issue

[jimmy101]

Starman covered the wiring well.
Solenoids for Orbit Watermasters are 24vdc and require 0.4A to open, and 0.2A to hold. (9.6w and 4.8w respectively.)

Hmmm, so using 9V batteries to operate two valves simultaneously is marginal. A typical fresh 9V battery probably can't quite get to 1A (9W), a partially used, but still pretty good, battery will be a fair bit less current (and power).

[starman]

Based on BCs current ratings, it looks like you could reliably trip and hold 3 solenoids. For each solenoid, 9.6 w @ 24 v would therefore mean a 3.2 w load per 9 v battery. 3.2 w X 3 solenoids is roughly the available power in one 9 v [fresh] battery.

In real practice, the good thing is that triggering a solenoid(s) on a spud gun is a very brief action..1 sec or so...the holding current wouldn't have to be in play for long. I predict the 3 battery setup would last quite a while even with 3 solenoids ..... assuming they are used only for triggering of course.