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Posted: 8/27/2011 5:05:11 PM EDT
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
Link Posted: 8/27/2011 5:17:31 PM EDT
[#1]
I used a 1200w to run my 'fridge in 2006.  It appeared to do it OK, but I never did it again, everything on the truck side was way hot.  I bought a generator a couple weeks after the storm was over.
Link Posted: 8/27/2011 5:21:23 PM EDT
[#2]
the question should be how long will my car battery last at full load on my 2200 watt inverter and how many amps can my 2200 watt inverter handle at 120 volts or 18.33 amps. now what you have to ask yourself what is the inrush current draw from my refrig when the compressor starts
Link Posted: 8/27/2011 5:28:25 PM EDT
[#3]
average alt puts out 100 amps so what,,, maby 1000 watt at 13 volt.
hard on battery and alt. battery will go dead depending on refer draw , 10-12 amp i guess.
not a good idea
Link Posted: 8/27/2011 6:22:59 PM EDT
[#4]




Quoted:

average alt puts out 100 amps so what,,, maby 1000 watt at 13 volt.

hard on battery and alt. battery will go dead depending on refer draw , 10-12 amp i guess.

not a good idea




100 amps average? Not so much. Most not at idle. (I play an engineer on TV and I actually build cars. )



OP needs to suck up reality and buy a generator if he really needs one.
Link Posted: 8/27/2011 6:23:59 PM EDT
[#5]
You'll have to keep the engine running to keep the battery in check. Car batteries are not designed to deep cycle.
Link Posted: 8/27/2011 6:31:11 PM EDT
[#6]
i run this 1250watt continuous inverter in a stock gm van with a 130 amp alternator. i can run all kinds of power tools including big hammer drills and a 3/4 hp air compressor. the inverter is wired directly to the battery with 2 gauge welding cable.
the truck always has to be running, and often needs to be held at about 1800 rpm or so to stay above 12.5 volts.
large inverters draw A LOT of current at 12 volts.

i would run my fridge off of it only as a last option
Link Posted: 8/27/2011 6:38:52 PM EDT
[#7]
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
––––––––––––––––––––––––––––––––––––––––––––––-
deficit = 30A to 100A

the battery has to make that up, until it is depleted.

ar-jedi
Link Posted: 8/27/2011 6:42:49 PM EDT
[#8]
Running a big inverter like that from a single car battery with a "run of the mill" alternator will likely kill your battery and your alternator real quick.

If you must, hook two or more batteries together with jumper cables, with the car running and attached.
Link Posted: 8/27/2011 6:48:18 PM EDT
[#9]
Quoted:

Quoted:
average alt puts out 100 amps so what,,, maby 1000 watt at 13 volt.
hard on battery and alt. battery will go dead depending on refer draw , 10-12 amp i guess.
not a good idea


100 amps average? Not so much. Most not at idle. (I play an engineer on TV and I actually build cars. )

OP needs to suck up reality and buy a generator if he really needs one.


I have a generator, but unfortunately it's one of those cheap assed harbor freight deals.  The inverter was intended for supplemental power, but the car has a full tank of gas and I figured that with the engine running it might actually be capable of supplying about as much power than the little generator.
Link Posted: 8/27/2011 7:02:53 PM EDT
[#10]


Save your car for its intended purpose.  Time to upgrade that generator, or bust out the candles.

Link Posted: 8/28/2011 7:12:07 AM EDT
[#11]
I think I agree with what most of the other posters said about it. It is pretty marginal to put that size of an invertor on a car battery. Having said that, as long as you are willing to run your car and use up fuel that way, for intermittant use, it will probably work OK. It probably won't seriously harm your battery or alternator, on intermittant use, but if you allow the battery to discharge too far, it will kill your battery eventually, and the extra load on the alternator probably will reduce its life as well.

I think planning to run a fridge for any length of time off your car battery is not a good idea. Maybe a small freezer for 15 minutes at a time with the car running.

Note the use of the word "probably" above. I am not sure that taking a chance on killing the car by killing the battery or alternator is a good idea at a time when you may need the car to bug out or go acquire needed emergency supplies.
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