Power Inverter an Option?

http://priups.com/

 

I think the threads about using a Prius as a generator were lost in the recent calamity.


The information on Priups.com is fascinating, and also very well written and illustrated. It's a great concept. We own a portable gas generator for emergency use, but have not yet needed it. How much more sensible to be able to use one's existing generator, i.e., the Prius!

If anybody actually puts these ideas into practice, I think everybody would love to hear all about it.

 

I think the other posts that you saw were simply good 12 volt inverters, that would run off any car's 12 volt system. Although they make more sense on a Prius, which could start up occasionally to recharge the battery, they are limited on the amount of power they can make, and therefore the number and type of appliances that they can power.

 

I don't think he's talking about adding any extra batteries, just building the circuitry and wiring to feed power from the high voltage system already in the Prius to your household.

Absolutely keep it simple. In a true emergency you don't want to be debugging your homebrew Prius High Voltage Interface. You want to plug in a standard product (12V inverter and extension cord) and gloat at your neighbors while your refrigerator keeps running

I'd ballpark estimate that you can get a little less than 1000 watts of 120VAC output from an inverter connected to the Prius. That might be enough to run your refrigerator or computer and a light or two. While it's true that you might be able to run your air conditioner as well if you tapped into the high voltage lines, the cost in money, preparation, size, and reliability to do that doesn't seem worthwhile to me. And besides if you draw 5-6kW as he suggests you'll burn through your gas in the tank awfully quick. Spending a thousand dollars or more so you don't have to suffer candles for a night or two seems like more than I'm up for.

 

1000 watts isn't enough to run a standard refrigerator. I went through this last year, suffering 2 longterm power outages from the hurricanes. I called GE and other appliance manufacturers, and they insisted that the startup current for a refrigerator is very high, like 3000-4000 watts, so they suggested nothing less than a 4500 watt generator. So, be sure to check whatever inverter you buy to determine how much peak or surge wattage/VA it can put out, until the compressor gets started. Once started, I believe my refrigerator did draw ~1000 watts though.

 

Your numbers are complete nonsense. If that 3000-4000 watt figure were true, it would blow the typical 20amp circuit breaker every time it started.

A typical Energy Star refrigerator only consumes around 160 watts when it is running. At startup it might require 5x its continuous power, so any inverter that can supply 200 watts continuous and 1000 watts during appliance startup should be fine. I just checked a 29.8 cubic foot Kitchenaid refrigerator on sears.com, it consumes well under 2 kilowatt-hrs of electricity per day. The 1000 watts you think your refrigerator draws is off by at least a factor of five.

 

Our local power company, Dominion Resources, offers a generator sizing guide on their website with typical start-up & steady-state wattages for a variety of appliances & HVAC equipment. Of course, the power company and generator manufacturers certainly don't have any incentive to underestimate load requirements, so theses figures are probably fairly conservative. Hope this helps.

See: http://www.dom.com/products/generators/order.jsp

 

Figure 1 in this document is an actual graph of the measured power consumption of an Energy Star refrigerator:

http://www.doa.state.wi.us/docs_view2.asp?docid=59

I did fail to consider the defrost cycle in a frostless refrigerator. The graph in the document referenced above shows consumption under 150 watts, but peaking near 300 watts once every 18-20 hours during a defrost cycle. The document also mentions a duty cycle of approximately 50%. .5 * 24 hrs * 150 watts/hr = 1.8kw per day, which is the same as that 29.8 cubic foot refrigerator (659kw/year = 1.8kw/day) mentioned before. That was also a big, $6000 Kitchenaid refrigerator; something more typical, like a 22 cubic foot top-freezer might consume 1/3 less power, or under 100 watts while running.

 

Here I Am

Here's the Inverters R Us link I mentioned and here's the inverter that was discussed. I can't see buying an $800 generator when this $129, 1,250 watt (3,100 watt peak) inverter running off the Prius will power a refrigerator, TV and a few lights or a fan for "days" (weeks, one of the Inverters R Us customers mentioned).

I ordered the 1,250 watt model and I'll keep everyone posted.

 

Just remember to protect the car. I remember calculating in the thread now gone that the car can only supply 1080 watts on the 120V side @ 90% efficiency. That means that 1250W inverter is prepared to pull more power than the car can provide from the 12V system, and we haven't even started talking about how many watts are required to power the car! I don't know what the maximum wattage is you dare draw, but you won't get anywhere near 1000W. Try 800W or less.

Does anyone know what the peak power requirements are on the 12V system for the car in a 'standard' running configuration? In other words, how much power should be considered UNAVAILABLE for use at the inverter?

Since all my threads touting it are now gone, I'd like to re-state that I'm still a big fan of the Toyota-supplied, circuit-breaker-protected, under hood, locking, high-voltage (HV) power connector! Man, what we could power with that!

 

Refrigerators vary a lot. I have an Amana that runs fine on my 1kw inverter.
My freezer on the other hand can't start. So I am switching to a 2 kw inverter
(along with big battery).

 

That's a cool application. My Prius sets inches away from my furnace, and even a gas furnace won't run if electricity is out! BTW, I'm in NE Indiana, just downwind from you...

 

Ok, don't have a cow, I was just repeating what the bozos at GE told me. <_< It would appear that they HEAVILY pad their estimates to protect themselves. :angry: Of course, they also may be taking into consideration that MOST people are trying to power an A/C unit, TV, or other appliances at the SAME time.
However, I stand by the statement that MANY 1000 watt inverters would NOT be able to start ALL refrigerators, depending upon their surge rating. I have several friends who burned out their refrigerator compressors last year, running them on generators that were too low in power capacity or overloaded. Compressors HATE low voltage, or insufficient startup current.

 

I have several friends who burned out their refrigerator compressors last year, running them on generators that were too low in power capacity or overloaded.

Huh?

Compressors HATE low voltage, or insufficient startup current.

Oh yes, didn't think of it like that.

I'd figure the DC/DC converter can handle somewhere between 80-100A. I'd say 800W 120V AC consumption would be safe.

Forget about resistive heating for a house. I think my house has an 8KW heating element in it for a 1300 sq. ft. house.

 

We have a generator that we use when the power goes out. It is a Honda EU3000is, which is rated
at 3000 watts peak, 2800 continuous. It runs our refrigerator, several computers, lights and stereo
gear just fine. It is also the quietest generator on the market.

 

Absolutely Correct

Heck, even a Hair Dryer can exceed 1200 Watts easily, and a room space heater would be evil.

Just turn the refrigerator around so the coils point out into the room and huddle around them. They'll be the warmest thing around

 

Well, since the law of conservation of energy still applies in this world, you aren't going to get much more than 300 watts out of those coils, unless you just went food shopping and bought a lot of meat.