If you need another battery we have a 650mAh battery and an 800mAh battery with a little longer runtime. Both fit right in.
The instruction manual by Absima can be found here:
Absima 1/16 manual
The electronics of the cars are splashproof so a little snow or mud shouldn't be a problem but cleaning the car properly right after is important. Clean the car off with an air compressor or a cloth and spray it down with WD-40 or a similar multifunction oil to leave a light protective layer of oil on the car.