Freezing water timers revisited

We have about a dozen battery timers about the property to water trees, shrubs, and the like, and with the coming of occasional winter-night freeze, wondering whether anyone here might have had some dealings or personal experience with the possibility of damage by freezing.

Left on overnight under pressure, at night occasionally cold enough here in the Mojave to damage its mechanism so we wrap with insulation, eg, 2-3 in. fiberglass supplied in the handy roll. Before wrapping, however, just how cold does it have to be, for how long, for sure damage

We don't care if ice formation interferes with operation of its valve or even blocks flow, but only if the mechanism will be damaged. Yes it's a tough one, with many variables, but I'd be happy to hear some rules-of-thumb

Incidental open letter to Orbit and other timer makers: Wrapping each one every fall or winter is such a nuisance I'm inviting our brightest a2k'ers to suggest alternatives to prevent such damage without wrap. Here's an easy one, a freebi:

As an erstwhile inventor myself, I'd have a temperature-sensing subunit inside which would open the valve a little bit at the critical water temp, a bit more with any further drop

If mounted at the external home-wall spigot the house water will prove warm enough. QB4 the house of course, especially in cold climes, typically how much water might it waste

But you guys are smarter'n me; so got any ideas