Disconnect ground cable whenever car will be parked for a week or more. Will improve battery longevity substantially. Not to mention decreased fire hazard. Even a clock, alarm system, radio memory, air ride suspension and general ECU parasitic draws can run a battery down. Miliamps do add up over time. The fewer discharge/recharge cycles the better for life expectancy.

I have a Ride Tech air ride system in a car which has a Optima yellow top battery. If I disconnect battery and check it 2 weeks later, still at 95 percent or better charge.

If I do not disconnect battery will be at less than 12 volts when measured, verses at 13 plus if disconnected. The Ride Tech ECU is an energy pig even with ignition switch turned off. Which suggests that a 1 month parking, car would likely fail to start.

Once a battery is completely discharged, even if you are able to recharge, it will never be the same. Most consumer battery chargers in fact will not be able to recharge the battery.

If you should experience this phenomon, there are methods to recover the battery. If interested enter a posting.