12 Volt Power

[NorthernSanctuary]

You're not using the right terminalogy for power. Electrical power is measure in watts, which is a product of volts X current (in amps). Power storage in a battery is related to it's size and type. Light bulbs are designed to work at a certain voltage, and you can always increase the voltage on a battery with a proper inverter. Then how long a battery will last depends on it's power storage, expressed as power X time. eg. a light bulb that has a certain output at 100 volts may draw 5 amps or 100vX5A= 500 watts of power. A 12V battery that is rated for 100A hour has a storage of 12VX100AXhr has 1200 watt hrs of energy. For that bulb, it can approximately light it for 1200watthr/500watt= 2.4 hours (it'll be less because some energy gets converted to heat in the battery).

The above assumes a proper inverter to raise the voltage to the required value and assumes no lose of power (which is not true in practice).