Overhaulin'

How long will a car battery last...?

Hi guys, This summer im hoping to use a car battery to power my music setup in the park. I'm planning to use a 300w power inverter to power the following: Mixer: 20w Speakers: 90w Laptop: ?unsure? The inverter specs are below. So....my question is..... How long will a fully charged car battery run the equipment. My knowledge is very limited on the subject so if i havent given ytou the required info i appologise! Thanks guys, Ross. Specs: Working voltage:DC11-15V Output voltage:AC220V±10% (For rated load) Maximum durative output power:≤ 270W Peak power:≤ 600W Output frequency:50±3Hz Output waveform: modify sine wave Maximum working efficiency:≤ 90% 12V output, the power consumption of the transformer in load-free state:<0.25A Ambient temperature:1 0℃~40℃ Lead report to the police: Outward appearance≤ 65 ℃ Under-voltage alarm:10.4~11V Low-voltage shutoff:9.7~10.3V Over-voltage shutoff:14.5~15.5V gross weight(packed): 1100g Volume:128×90×49mm Material:The aluminum metal alloy( high pressure etc.the ion oxidizes the surface) color:Cultured silver packing: vacuum plastic packing

Public Comments

1. You need to know the reserve capacity of the battery in amp hours. For example, 50 amp hours means the battery will be able to supply 50 amps for 1 hour, or 1 amp for 50 hours, or 25 amps for 2 hours, or 10 amps for 5 hours, etc. Use the equation: Power (in Watts) = Amps * Volts to figure out how many amps will be drawn off the battery. If you only know the power being supplied on the inverter side, divide the power by the efficiency. For example, if the inverter runs a 100W light bulb, and the inverter is 90% efficient, the inverter would draw 100/0.90 = 111 Watts. So we have our current draw = 111W / 12.6V = 8.8A. Now we take 50Ah / 8.8A = 5.67 hours. Now you can do the same math with the values appropriate for your application.