CR1632 operating specification is up to 60 degrees C or 140 degrees F. Life decreases with increasing temperature.I haven't found anything anywhere, so i'll ask here.
Do you think the rmr on the RX would last in a hot car (texas), for the day? Or is the heat likely to cause the battery to burst?
Not only the battery but most optics might use some sort of adhesive that could melt and ooze. In addition, the coating on the lens might get damaged.Definitely do NOT leave battery devices in a car. Temperatures in a automobile can exceed 200 degrees in some areas (Phoenix) and the resultant heat and expansion can cause devices to rupture.
Worse yet is direct sunlight impingement on some devices. Having seen what happens when a Cell phone is left in a direct sunlight area with no airflow for 2 hours, I can tell you that things DIE.