I am new to the hybrid website even though I own two hybrids. Here in the midwest we have been hit with ice storms and have lost power several times. I was looking up inverters and found a user feedback where the owner of a hybrid put jumper cables on a deepcell 12volt battery and connected to his hybrid's under hood 12volt battery. The deepcell battery was connected to an DC to AC inverter that powered his home during a hurricane power outage.
MY QUESTION IS WHAT IS THE AMPERAGE OUTPUT FROM THE 330VOLT POWERTRAIN BATTERY TO THE 12VOLT DC UNDER HOOD ACCESORIES BATTERY? IF I KNEW THIS RATING I COULD THEN SIZE MY INVERTER TO MAXIMIZE MY HYBRIDS BATTERY RECHARGING TECHNOLOGY.

I think the 12v battery only gets a couple of charging amps since it is not intended to do very much.

Maybe this might be of some related interest, (More) Power to the People: Run Your House on a Prius. However, this story is about drawing directly from the HV battery, and not the 12v battery. Though I have my doubts that with only 3kwatts, one can run everything in the house except for the central air.

Best single LD trip: 35.3mpg

See my prior post here:

http://www.greenhybrid.com/discuss/f...nerator-15819/

The answer is 110 amps at 12 volts, or 1320 watts.

Can you really just "pull" 110 amps out of the 12v system "as is"? I mean, were would you even tie in, at the 12v battery's terminals? At the HV DC-to-DC converter's 12v side?

And wouldn't that force the ICE to run continuously, for reasons similar to why the rear defroster forces the ICE 'on'?

Best single LD trip: 35.3mpg

Yes, you would pull the power off the 12 volt battery terminals. I assembled the 1000 watt inverter with cables and a 200 amp fuse, but have not tried it out yet under load.

I don't know what logic turns on the ICE with respect to DC load. Anyone know?

I did some experimentation on my 07 FEH today and I found that when it was in EV mode, turning on the rear defroster did not kick on the ICE. I also turned on the head lights, fog lights, radio, blower on max, brake lights on - same thing, no ICE running.

I still have not hooked up the inverter to see if that kicks the ICE on.

The HV battery "likes" to be in the 40-42% battery SOC range.
If you are not driving the car, and you are just parked, the ICE will cycle to keep this narrow band of charge. That is not very much wattage folks, so yes, the ICE would run nearly the whole time if you tried to pull 1000 watts ( or more ) continuously. However, if you are camping, etc. And only need a couple of 100 watts at a time, or 1000 watts for 20 minutes, you could manually charge the HV battery to 53% ( via leaving the A/C or defrost on in Park, and then turning the engine off manually with the key, and then putting the key back to run without a start. This would allow you to use the battery from 53% down to about 35% on one cycle without the engine on at all. If the HV battery dips below 35% it cuts out to protect itself, and also to save enough juice to restart the car, but does not cut off the 12v battery, so you could drain that one till dead. This would give you about 350 watt hours, or 1000 watts for 20 minutes, per each ~5 minutes of engine run time.

I have been able to pull 1400 watts off the 12v (14v) system without issue for like 20-25 minutes once with engine off.

The 12v battery does not provide power to anything when the key is in run, only when the key is off or to ACC. The HV battery is connected to the 12v battery via DC/DC downconverter, and when the key is in RUN, you can't really distinguish one from the other. The HV battery provides all the juice when the key is in run, if you put a wire tap right on the 12v battery, or cigarette lighter, it doesn't matter.

Thanks for the informative post, gpsman1. To put it in perspective, my old inefficient refrigerator draws 200 watts when it is running (which is not constant). New ones draw half that. So for keeping your food cold in a summer blackout, or running ten 15 watt compact florescent light bulbs, or a laptop computer, an inverter could make your house a whole lot more livable during a blackout.

As I stated earlier, I have a big gas generator, but it would really be nice to have a way to generate quiet, clean power when only a small amount is needed, like through the night.

My next task is to determine if the inverter will run my gas furnace. A power outage in winter (in Michigan) would really require that the furnace could run all night. I noticed on an internet blog for a Prius with an inverter, that the modified square waveform inverter was inadequate to run a modern high efficiency furnace with electronic controls. My furnace is older, but this may be a consideration for someone else considering an inverter backup. They would need to pop for a true sine wave inverter, which is more expensive.

Thank you for all the informative answers and suggestions.

That may be true of your fridge while it is running. But I think when the compressor kicks in the load is substantially higher. You need to figure out what the MAX wattage the fridge needs when it cycles on.

-Tim

2006 Mercury Mariner Hybrid AWD
Black with Pebble interior
Premium Package with Nav & Moonroof



Current ODO: 22,909
Typical Drive: 20 min crosstown in heavy traffic (3.5mi there and back twice a day)


457 Gallons of gas saved
That's 9,150 lbs less CO2