trickle charging
 

if one is using a low power "trickle" type battery charger to top up the battery in a cold winter, is there a danger of overcharging a battery or does it merely stop taking a charge past a certain point?

That depends on your charger. It set to a low trickle charge such as 2 amps you probably do not need to worry. But .... remember the by product of a charging battery is hydrogen gas. Keep the hood up and the area well ventillated.

Turn off the charger BEFORE disconnecting the charger cables. Also, if the battery is getting over charged, it will tend to boil the battery acid and you do not want that bubbling out and all over your car. Trust me on this one ...

Haasman