Quoted:
I have a 2200 watt inverter that I bought to hook up to the car for emergency power, but it's unclear how to hook it up or how much juice I can draw. Is it like hooking up jumper cables where you go to the positive terminal of the battery but ground to the engine block? And how much power could I draw without frying my alternator? Could it power a fridge?
Thanks
the inverter is rated at 2200W maximum output power at 120Vac. on the input side, your vehicle electrical system will need to provide 2200W/13.8Vdc * 1.2 = 191Amps. (the reason that the factor of 1.2 is in there is because the inverter is only about 80% efficient in converting the input power to output power –– the rest is lost as heat.)
so you need 191A of automotive electrical system capacity for full output on the inverter.
a standard automotive alternator might range from 90 to 130A charging capacity, with larger trucks and/or RV's equipped with 140-160A alternators. also note that these output currents are only available a elevated engine RPM's. at engine idle the output current may be less than half of what the rated current is.
so at 2200W output you have a checking account problem here:
power being drawn = 190A
current being supplied = 90 to 160A
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deficit = 30A to 100A
the battery has to make that up, until it is depleted.
ar-jedi