Hi folks,

Just as the sun was setting, south Huntsville had a complete power outage when a power substation had an insulator failure. The Huntsville Utilities reported the power outage covered an area about 5 by 8 miles. So I drove out of the power outage area to fill up the Prius and returned to plug in some of our house appliances.

Now I've only got 1 kW, ~9 A. @ 110 VAC, of inverter power. So we started out in the TV room with a fan, lights and watched the Lewis Black special on cable TV. But after a couple of hours, the cable system also went dark and we switched to broadcast TV in the bedroom.

As part of our air conditioner rework, we're using window ACs and the bedroom 5,000 BTU unit works just fine on Prius power along with the 19" TV. I checked and we're drawing 50 A. on the Prius auxillary battery bus or a little over 700 W.

Just as I was finishing this note, at 10:45 PM, power was restored. But there were a few lessons learned:

1. need in-rush limiters - the cable box, 27" TV and laptop power supplies all have significant in-rush loads that can exceed the 1.2 kW surge capability of our inverter. A larger inverter could be used but it makes more sense to install in-rush thermisters on the offending devices. This will also reduce their effects on normal house circuit power too. Also, a larger inverter might overload the Prius auxillary charging circuit and blow the 100 A. fusable link, a bad thing to do in an emergency.
2. need separate, emergency power outlets - although the contractor extension cords are OK for now, they are a trip hazard and have to be taken-up afterwards. Worse, they require the kitchen door to be 'open'. What I need to do is install a heavy gage, circuit with the all-weather interface located in the car port and a good earth ground. A current and voltage gage can be located in the kitchen so we can monitor the loads from the house. Each house outlet will have a small LED 'night light' with one in the TV room, utility closet for the gas heater, and master bedroom.

The next morning, I topped-off my tank and another guy was filling his 5 gal. gas can for his home generator. After adding my 0.2 gal, I showed him my trunk mounted inverter and gas recept. Obviously, I had just topped off my 11 gal. emergency generator versus his 5 gal. gas can.

Of course he has whole house power and my 1 kW unit is just enough for dealing wth a power outage . . . 'camping out' in our home. Still, 1 kW works very nicely and with a 5,000 BTU bedroom air conditioner or running the gas furnace fan, we can handle both the Alabama heat and occasional ice storm.

Bob Wilson

 

Well, it is good to know that your 1000 watt -$20,000 generator-can kick on the 5000 BTU AC.There isn't anything special about the window unit-regular 9.7 EER unit 520 or so watts steady? I had wondered about that, since I was considering doing the Prius/Gen deal.Al is just about as hot/humid in the summer as NO-the AC is first order of business.Thanks,Charlie

 

Is it a standard Sears unit bought on sale last fall, $90. I start the fan on high and then turn the thermostat down to kick in the compressor. If you can cool the bedroom you can get a good night's sleep and life is good.

Bob Wilson

 

good data bob. I like how you don't let a power outage ruin your fun

 

Hi Bob. Tried to respond to this post in yahoo technical but they are clogged up.


For those considering adding an inverter. I would like to mention an unusually low price noted for a 600 watt (1000 peak) pure sine wave inverter

http://www.mwave.com/mwave/viewspec....iteria=AA39610

Have no experience with the Fujiplus brand but I bought a computer once from mwave and they were OK.

DAS

 

Hi Doug,

I noticed the Yahoo groups seem to be suffering some problems. I know Hobbit and some of the others are unhappy with the e-mail changes. Yet the group has such a good collection of technical papers and message archive, it is hard for me to walk away from them. Someday we should discuss the advantages and disadvantages of GreenHybrid.com, PriusChat.com, CleanMPG.com, Yahoo's groups and USENET.

Good point and something I failed to mention.

The NHW11 (and probably the NHW20) can provide 1 kW on the 12 VDC bus, 24x7. The only remaining questions are pure or modified sine wave and built-in instrumentation.

I'm using a modified sine-wave inverter which means the small broadcast TV shows some 'noise' lines on the monitor. However, they were not annoying and there was no impact to the sound. The modified sine wave inverter literature also suggests that light-dimming and some florescent light systems may not work. Also, some industrial motors don't work well with modified sine wave power. So far, we haven't had a problem with any of our motors or electronics beyond the noise lines on the 19" TV. Just be sure and test the applicances while you can still return the inverter.

A pure sine-wave inverter aleviates all of these problems but they often have lower efficiency than a modified sine wave inverters. Regardless, a 1 kW rated inverter with a modest surge capability should work just fine.

I've also seen inverters that have power load indicators. IMHO, this is desirable especially if you don't have a nice set of instrumentation. But it is even nicer to have the power meters inside the house.

Bob Wilson

 

You should try to get ahold of one of those big computer system UPS that can handle 200-300v, then once your warranty is up you can have quite a bit more power, depending on the capacity of the UPS.

 

Hi Erick,

Richard went that way and it certainly was a good approach. But I believe he is limited to 3kW. I'm looking at a different approach.

I've got a spare inverter in the garage and I'm planning to see if I can drive it from a ucontroller. If I can, it will be trivial to put together a three-phase, sine-wave power supply, my approach to whole house power. Initially, it will plug in via the trunk and be trunk transportable. The power limit would be what ever the NHW11 will generate parked in the driveway, potentially nearly 18 kW.

Initially I was planning to drive the house directly but vehicle ground-fault isolation requires a transformer. Also, there is the problem of getting 220 VAC RMS from my 273 V battery but the isolation transformer might solve that problem. Regardless of the approach, this looks to be a solvable problem.

Bob Wilson

 

My added inverter is also modified sine wave (msw), and I have noted minor power issues with it Some electric motors will run slower, and I've read that motors may generate more heat on msw. I have had no problems with battery charger power supplies and the like. But again, I have read that some switching power supplies won't run on it.

Really the main problem I've encountered is that its internal temperature control seems to be too sensitive. When ambient temperatures are above 95 oF it won't even supply power - just runs its two fans and alarm beeper. It is sold by "Whistler", 1000 w continuous. It may be in my best interests to be conservative on hot days, but not even giving me 1/2 power output? Seems wrong.

That $90 price for 600 watt pure sine wave is extremely low within the market, and I was kinda hoping that someone would give it a try.

DAS

 

Not being an engineer, would someone in more basic technical terms explain what the goal being discussed in this thread is?

Am I correct in surmising that you all are using something called an inverter hooked to your Prius to use the Prius as a gas powered generator?