Proper way of charging a battery
 

I have a 1999 ML430 which has 80,000 km on it. Still has the original battery. I am not driving it that much these days now that winter is here and with the price of gas. I may drive it once every 2 or 3 weeks so the battery doesn't get fully charged just by the amount of driving I do now. It is garaged always and the temperature inside is typically around 0 deg c. I would like to keep the battery charged up. I have a battery charger with automatic shut off. What is proper way of charging the battery. The Mercedes manual say the battery should be disconnected before putting on the charger. I have two other Volvos that I usually connect the charger with battery still connected with no problem. Is there a reason that the ML is different? May be because of its electrical system? It just seems a lot of work to disconnect the battery every time I put on the charger.
If I have to disconnect the battery, is there a procedure I need to follow and also in reconnecting the battery?

Thank for any help.

i have seen power surges cause some issues, especially if the key is in the ignition while it is charging or if it is there when the battery is disconnected power surges will cause the key to be removed from the aam's authorized keys and will result in a no start. best bet is to remove the key and disconnect the battey and then charge it

thanks

is there a procedure to disconnect and disconnect the battery for the ML. is there a need to reset any alarm, computer etc. when reconnecting the battery?