Purchase a trickle charger and keep it connected to the battery.
Usually yes if alternator is good not a good idea alternator can burn out all your components without the battery to keep the voltage down
Yes. It is a myth that a battery will run down sitting on concrete.
Leaving a battery sitting on a cement floor will have no effect whatsoever. It will not discharge the battery anymore than letting it sit in the car or on a wooden floor. That is a myth. Just put a charger on it and charge it. If it does not take a charge it is defective, but sitting on concrete did not cause it to go bad.
Keep the car light on
The battery goes dead
A healthy, fully charged car battery will eventually go dead just from sitting, but it takes a very long time.
Easyer to just disconnect battery for the time the car is sitting up.
Could mean that your alternator is bad and is stopping it from regenerating the power.
Something is pulling power from the battery when the car is sitting idle. Check under hood, trunk, glove box lights, etc. Also can be a stuck relay. A battery may also appear good and have a dead cell. Have it tested.
The first thing you want to check is your battery state of charge. If your car has been sitting that long, I can almost guarantee that your battery is dead. If it's been sitting that long, your best bet is to replace the battery.
using car maintainer,,,, There is a big difference in a regular Battery Charger and a Battery Maintainer. A Maintainer will keep a battery charged and can be connected full time without overcharging. The usual Battery Charger is for intermittent use at times when your battery is so weak that it must be recharged in a short time, then disconnected from the charger to keep it from overcharging. A good Maintainer can not overcharge.
The problem is probably the alternator. If the alternator fails to keep the battery charged the battery will keep the car running until it can no longer supply voltage to essential systems and the car will stall.