Recharging your bark control collar, GPS dog collars tracking system, Remote training system or dog fencing system in winter can affect your rechargeable batteries health. Generally speaking recharging any product in temperatures below 0 degrees C should be avoided. Internal resistance of all batteries rises in cold conditions. This may lead to poor battery performance. Again speaking in general terms the temperature spread when to recharge is 0 degrees to 45 degrees C . If you keep your system in an unheated shed and charge your collars at night when the temperature drops below 0 C , I suggest you bring your recharging system into an area that is warmer than the unheated shed.