[Gilgorm]

My battery had the low warning once in the winter of 2012-2013 when the car was about 7 months old. I already own a charger with 2, 15, and 100amp settings so just charged it. I've used it just the once. My 535xi usually only runs for 7-10 kms in the city every other day and hasn't been on a highway for a month. I often use Sport to increase the rpm as others suggested. I doubt you would need to use the trickle charger every day, even when its extra chilly, but it won't charge the battery so you may still want to use a regular charger. The three settings in mine are for trickle, regular and super start. I got it at Canadian Tire.
My F10 lives outside. If your battery is three years old it may just be wearing out.

BTW, my retired E60 had two batteries in 2.5 years and I used the same charger a lot with it. E60s had a lot of battery problems due to the car not going to sleep when it was turned off. Based on forum comments, F10s don't seem to have as many problems in this regard.
Good luck.