i want to run a 115 v,5k BTU A/C using a 12 v dc/115 ac inverter hooked up to my Chev van. will this work ?

Question

if this would ,work what size { wattage) inverter would i need.?

Answer 1

Check the amps rating on the AC unit. Wattage is a function of voltage and amps. use P=power (watts), I=current (amps), and E-voltage (volts). P=I times E, so if your AC unit needs 10 amps, then wattage (P) is about 1200. Over rate the inverter by at least 25%, so 1200 times 1.25 gives 1500. You need at least a 1500 watt inverter. If this is an older AC unit, the startup current (amps) will be much higher, so 2000 watts would be more appropriate. [these numbers are example only, do the math for your unit]

Anyway, since we can do the math on the 12-volt side just as easily, 2000 watts at 12 volts gives us about 170 amps (P=IE, or I = P/E) - more than any standard auto-electric system I know of can support. So the answer to your question would be no, at least from a practical standpoint - you'll be better off buying a small, gas-powered generator set.

Sorry - good idea, but no.

Answer 2

You need the actual data plat rating to determine this. Besides the "running" current, you have to worry about "inrush" current. That is when it first starts , or when it starts under high head. You may only need 1000 or less watts of running inverter watts, but you need to size the inverter large enough to supply the startup current which can be 1.5 to 2 times higher. I would look for 2000 to 3000 watts of inverter power. and you will need about 100 amps of alternator to barely keep up.

Answer 3

Take the 120V and multiply it by the current that the AC unit is rated for. That will tell you the wattage needed for the inverter. For example, 120V @ 15 A = 1800W

Add about 20% to that figure for safety and loses, you would want either a 2KW or 2.5KW or even a larger inverter to handle the load.

good luck.