Your battery is bad, your alternator is bad or you have a wiring problem.
A battery that won't hold a charge has a dead cell and must be replaced. This is assuming there is not something on that is pulling power from the battery.
Depends on the condition of the battery. Most will hold a charge for at least 6 months if they are not connected to anything.
Battery is getting old and will not hold a charge or there is a drain on it. Battery is getting old and will not hold a charge or there is a drain on it.
14.5 gallons
I assume you mean if it is stored. It depend on the battery and what condition it is in. A good auto battery will hold it's charge for at least 6 months.
Yes, it will hold it's charge for at least 6 months in storage if it is a very good battery to start with.
Batteries charge nothing they hold a charge.
It will hold 4 quarts.
Any light on the vehicle that is on all the time, and any relay that is stuck. Also if the battery has a dead cell it will not hold a charge.
bad battery
Remove the negative cable over night. If it does not hold a charge, the battery has a dead cell and needs replacing. If it does hold a charge but will not when the negative cable is connected you have something on that is drawing power from the battery. Some light or a relay is stuck.
The battery brand itself doesn't matter. It depends on how much charge the battery can hold. A good way to improve battery life is to charge it only when your phone is down to the last bar . Don't charge it unnecessary.