Several things could be in play. Either the battery is defective and won't hold a charge, the alternator is not charging the battery or there is a parasitic draw on the battery when the car is switched off. The battery is a reservoir of electricity but if it sulfates and goes bad it just will not hold a charge. Have the battery charged and tested. Make sure the battery connections are clean tight and secure. The alternator replenishes energy taken out of the battery once the engine is started. The alternator generates electricity and recharges the battery. Turn on the ignition switch to the on but not run position do you see an icon on the instrument panel representing a battery, if you do not see this battery icon the alternator is not seeing power to allow it to charge. Start the engine does the battery icon go out. Put a volt meter across the battery terminals with the engine off, at rest the battery voltage should be 12.6 volts if the battery is fully charged. Now get a friend to start the car while you watch the voltmeter, the voltage reading across the battery should read approximately 14.6 volts if the alternator is charging correctly. If the alternator is charging properly and the battery tests OK then you may have a "parasitic draw" on the battery. A "parasitic draw" on the battery is something that stays "live" stays switched on even through the car is turned off and the keys are out of the car.
i have a good charged battery,no power what so ever in the car,neg lead cable is corroaded at battery clamp housing