You haven't supplied enough information. An inverter only converts 12V DC to 115V AC. There are some battery packs with inverters, but that's not what you asked about. The time it "serves" is dependent on the load being connected and the battery(s) that the inverter is being supplied from. Go to a web site such as :http://www.donrowe.com/inverters/inverter_faq.html#hookup You can learn a lot about inverters here.
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You haven't supplied enough information. An inverter only converts 12V DC to 115V AC. There are some battery packs with inverters, but that's not what you asked about. The time it "serves" is dependent on the load being connected and the battery(s) that the inverter is being supplied from. Go to a web site such as :http://www.donrowe.com/inverters/inverter_faq.html#hookup
You can learn a lot about inverters here.