4 years is about average for a car battery.

Automatic or smart chargers, like Battery Tender, won't charge batteries that are under 8 volts or so because their anti-spark feature uses the battery to turn on the charging. So your idea of connecting a dumb charger at first will usually let the automatic or smart charger work, but you may have to use the dumb charger a lot longer than a few minutes. Actually a dumb charger the size of #2 can be left connected for days because its output current is too low to damage the battery in that time.

Considering your climate, you should probably get a 4-10 amp conventional charger, either manual or automatic, such as one of the models made by Schumacher (includes Sears Diehard), but make sure it has a 3-wire AC power cord for protection against electrical shock, and plug it into a 3-prong grounded outlet (not all 3-prong outlets are grounded), through a 3-wire extension cord. You may think 2-wire is OK if the AC outlet is protected with a GFCI (Ground Fault Circuit Interrupter, a device to prevent most electrical shocks), and it usually is, but I had two GFCIs fail on me, one in the "on" position, and sometimes there's so much moisture outdoors that the GFCI will trip often, requiring you to change to an outlet that isn't protected by a GFCI, but the only way to do that safely is with a 3-wire grounded hook-up. Do NOT use 2-wire equipment or a 2-wire extension cord with an AC outlet lacking GFCI protection! If you get GFCI tripping, unplug the AC outlet, and elevate the extension cord connection off the ground and away from metal, then plug it back into the AC outlet. Remember, any time you're handling an AC cord outdoors, have it unplugged from the outlet.

Charge up the battery before any expected rain or snow.