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Power Inverter

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briant67

New Member
I bought a 3000 watt inverter to power a portable air conditioner in my ford windstar.It runs fine for 10 minutes then shuts down because of a low voltage reading.Do I need to buy a bigger battery or maybe a power capacitor or... ? I have invested about 800 into this venture and still no ac.I should have just had a complete ac system installed.
 

ChrisP58

Well-Known Member
Most Helpful Member
What is the actual power drawn by the AC unit? Even if it were only half that of your inverter, it would still draw about 150 amps from a 12v battery. You will need a really big battery if you want to run it for very long. Even if you are running the engine at the same time, you are still drawing it down much faster than most alternators can charge it.

Please note, that the CCA (cold cranking amp) rating of a typical car battery is not it's amp-hour rating. While the CCA rating are often >500. the AH ratings are usually less than 80AH, some are less than 50. And, if you are drawing very high currents, the effective AH capacity goes way down.
 

ChrisP58

Well-Known Member
Most Helpful Member
I can't answer that without knowing more about your setup.

- How much power does the AC unit draw?
- What percentage of time will the compressor be running when in use?
- What is the efficiency of the inverter?
- How long do you want the battery to last?
- What is the rating of the existing alternator?
- Is there any time when the engine will be running to recharge the battery when the AC will not be running?
- Is there any other source of power that can be used to recharge the battery other than the engine alternator?
 

tcmtech

Banned
Most Helpful Member
First off a quick way to find what your AC unit draws is to read the power input label.
Divide the wattage by 12 and thats the amps your 12 volt system has to supply assuming 100% conversion efficiency.

For a more accurate number divide that number by .7 and you will be close to what your alternator has to supply above and beyond what it was rated for from the factory.

Odds are you will be needing a 250+ amp alternator plus the necessary heavy gage wiring which will cost far more than getting the vehicles original AC system working like its supposed to. Not to mention the cost of the safety violation ticket you will eventually get for having a home AC unit hanging out one window. :eek:

Either way can we have a picture of your Windstar with the home AC unit installed?:confused:
 
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