PS I have one car which I use infrequently and unless I disconnect the battery it requires a jump start after about 3 wk or a month. The battery in it is new and the charging system tests fine. I think it is due in my case to standby losses (burglar alarm, ECU volatile memory, etc). Sometimes a defect can occur up which causes a high standby drain - you can have the current measured in your car with ignition off to check that.

If the regulator is working properly it will limit the charging current output from alternator to a safe value even if the battery has one or two shorted or weak cells which try to hog current. However the battery then will no longer hold a charge.

Never disconnect the battery while the engine is running, don't short circuit or exchange the plus and minus leads, and do not allow a crude tow-truck jump starter to be used on your car because these often produce severe overvoltage. It's safest if you get stuck before you get to replacing the battery to get a jump from another car.

Otherwise the electrical system is fairly tough.