Dead battery, cigarette charger, and horn chirp

[kk2002s]

A bit of a hijack here
With the cold we are getting lately here, I'm just letting the car sit in the garage for the couple weeks until the road clear and temps go up. I want to do a trickle charge in this ex-stream cold. I could go through the lighter but is it Ok to directly connect to the battery while it still connected to the car.
I don't want to disconnect the battery and have to go through the reset process
I drive the car year round but now that I have an extra car I can sit the box in bad weather