How long will a fully charged 12V car battery run a 29W compact fluorescent bulb?

Question

How long will a fully charged 12V car battery run a 29W compact fluorescent bulb?

Answer 1

29 watts is about 2.5 amps of 12 volts, assuming a perfect efficiency in any conversion required.

if we had a 25 ampere hour battery it would last 10 hours. for other battery capacities time would be proportional to amp hour capacity.

If you have to run it through an inverter, you could be losing half your power, as teh inverter is not likely to be sized for 29 watts.