both my Nokta FORS CoRe and Impact User Manuals, it states the following:
► Do not store the device and search coil under extremely low or high temperatures for extended periods. (Storage Temperature: - 20°C to 60°C / - 4°F to 140°F)
One thing I have found, over many decades of year-long detecting, is that my body tends to give in before most detectors will, when the temperatures start to get on the low end. Also remember that performance when it gets cold can be effected by the wind-chill temperatures, not just the ambient read-out. And cold temperatures seem to effect the batteries before the detector's electronic components.
You can also consider using environmental covers to help, or even try slipping a hand-warming packet inside between the environmental cover and the control housing. Trying to select wind-sheltered areas helps, as well as hoping for sunny weather when it gets cold. In years past my 'body gauge' tends to switch to an 'Indoor Research-Mode' rather than an 'Outdoor Detecting Mode' when the temperatures start to hang-out around 38° F and below. When I was younger I got in what hunting I could if the ground was still workable when it was at or just below freezing, about ±30° or so, and below that the detectors & I stayed inside to keep warm and comfortable. Hunt times were rather short.
My current age and health during this past decade or so favors warmer weather. I still get out for short hunts when it is maybe 38° to 40° if it is a quick-hit location with easy recoveries, such as tot-lots, or even some torn-up sidewalk repair, etc. Most detectors I use haven't given me any problems since the late 1980's. Nokta's comment said "Do not store the device ...." and I take note of that caution because it refers to 'storage' and not 'use.' Once late fall and winter arrive, I bring my detectors in from the vehicle for the season and only take out a device or two when I go detecting.
During the warmer spring and summer weather, or early fall when temperatures don't get into the freezing and below range, I tend to keep 2-5 detectors along with me at all times in my vehicle. I keep them inside, usually on the back seat, and covered with a white hospital blanket to keep the direct sun from hitting them. Often I keep a windrow cracked open a little, park in shady areas, and have never had a problem related to temperature extremes. Until the daily highs are above 95° when it gets unpleasant for me, then I consider it unpleasant for the detectors and we all stay inside and out of the vehicle and heat, only being taken out specifically for a detecting jaunt.
Last January I headed to some snow-free areas in the adjacent state of Indah to do some evaluation with the Impact and there was no snow, but the daily high was 19° F. It was a calm, wind-free day, clear skies with ample sunshine, and the Impact worked fine and I am sure could have endured a longer hunt session than I could. It included short sessions then back in my pick-up to get warm before another short session. Other than that I held off detecting until I got into temperatures that were into the mid to upper 30's and warmer.
So, there you have the manufacturer's storage temperature warming, and only have to factor in your personal ability to endure the cold to very-cold weather. The best of success to you when you do take on a challenge with mother nature.
Monte
