Prius as generator, worked as advertised

Thanks for the update. (You're in NoVA, correct? I saw the news reports of the severe weather up there yesterday.)

This idea has had some appeal to me for some time, but the various descriptions from those who have done it intimidate this non-technical soul. I did two years of vocational electronics in high school some 30<mumbles> years ago, but about all I remember is Ohm's law and some naughty mnemonic to remember resistor color codes. Something about bad boys and young girls.

Anyway, you make it sound pretty easy. Is it really that simple, and what set of instructions did you find most helpful?

My fiancee especially is hosed when the power goes out -- or not hosed, depending on how you look at it. She's on a well, so she loses her water along with her power. She's on a tight budget and she's been reluctant to buy a generator.

I'm not sure 1500W would handle both the fridge and the well pump together, but then they don't have to run simultaneously. I figure we would keep the fridge on most of the time, swapping it out with the well pump when we need water.

 

Totally cool...

I GOTS ta look into this angle for my Calaveras property.

Thanks for the data, glad you made out OK.

 

This looks interesting. Can you give me some details on the brand and cost of the inverter? Any pics?

Thanks

 

I wish this would support a 3000watt draw... My wife and I are starting to live full-time in our RV, and we don't want to have to leave our camping spot (for a spot with hookups) if we start having generator problems and the weather hits 100+ degrees this summer. My wife would probably just tough it out (she's ex-army), but we have a 4month old baby that we're, you know, "babying".

I guess this would only help on the 2nd day of generator problems because I would probably have the prius at my job when the gen stopped running. The truck we use to tow our RV is somewhat efficient (22+mpg for a 9000lb truck), but diesel costs more than gas now, and I often have to commute a long way. Right now 80mi/day. That means the prius is not at our campsite if I'm working.

It's very good to know we can leave the prius on and locked and have it maintain its' battery charge. Sometimes we need a 12v boost, and running a 3000watt generator to charge my trailer batteries is very inefficient. At least our generator is extremely efficient for its' size. 4.9horsepower inverter generator with a 90+% efficiency inverter, I just wish it was more reliable. Think I'll be buying a honda EU gen this summer if I can find the money.

priusdriver:
like the original poster said, there is a huge difference in price between the modified sine wave and true sine wave inverters. I use a modified sine wave inverter because all my stuff runs on it just fine. I have a xantrex 1750 modified sine wave and I believe we paid around $180 at costco a couple years ago for it. There are SOME AC motors that will not run on a modified sine wave, and the other notable exception is that laser printers will not work on modified sine wave.

The reason I didn't buy an inverter large enough to power my trailer AC unit (3000watt) is because there's no 12v source available to me that would be able to provide that much power for long. If our diesel truck had a modified alternator (and possibly a high-idle switch depending on the alternator) maybe it could handle that, but that is at least a $700 modification and I will be putting that money towards a better generator that would be more fuel efficient than a diesel truck idling.

 

i would also keep the hood open. any time i use my prius for extended electrical use. i tend to prop the hood open so the engine and hybrid system can keep cool.. otherwise the electronic fans kick in and you lose more energy! plus... with the very few inverter problems i've heard.. i would like to keep it protected where none of the systems get hot enough to kick on the cooling fans.

 

Cool. I'm also planning to build some sort of 12v "Priups".

This is one of the reasons I decided the Prius could save me money versus buying a generator and another car. Also means I don't have a generator to maintain, as long as the Prius is maintained and gassed up.

I'd like to get 3000 watts, for motor startups and burst usage at least. Normally this would been I'd have to hookup to the 200v hybrid battery. I want to maintain my warranty however, so I'll stick with the 12v system.

I'm planning to build a 120v "power pack" from a big lead-acid deep discharge marine battery and a modified sine wave 3000w inverter, perhaps from Xantrex. This will be somewhat portable and will be usable standalone.

If there is a power failure and I require house backup, I'll move my power pack near the Prius and hook it up to the Prius 12v battery to recharge the marine battery and power the inverter. I'm thinking I'll be OK with 1000w continuous, and the marine battery and inverter will be good for 3000-4000w bursts.

If modified sine wave doesn't work with my furnace motor, I'm thinking of replacing it with a high efficiency DC motor. I think I'll save money on a DC motor based on electricity cost too, since I let it run for house ventilation all the time.

Another thought is to have a smaller pure sine wave inverter in parallel to handle equipment needing cleaner power.


As for leaving the hood open, I think I'd prefer to close mine, especially if rain or snow is expected. I don't think the Prius electric fans take much power. I might consider leaving the hood open in very hot weather however, but we get less of that here in Canada.

 

Unless this a shallow well, it most likely uses a 240V pump motor which is a whole different beast where inverters are concerned. If it is 240V you may be able to use a step up transformer to convert 120V from the inverter to 240V. I've never tried it but I think transformers will work with a modified sine wave input. In any case, 1000W is only 1.3 horsepower which is a pretty small well pump motor even assuming no losses.

If memory serves me, I needed at least a 3500W generator when I ran my well pump during the camping phase. It's a 285' deep well.

 

You can get a noisy (okay, they're actually quieter than the average contractor gen) 3500w generator at harbor freight for $250, which has built-in 240v output. Unless it's a really small well pump the prius is probably not quite suited for this situation, I agree.

EDIT: as an example, the property we've been living on for the last year has a well pump also. The well pump draws so much power that we turn its' switch off before starting up the 30KW diesel generator which we start up when the power goes out. The well pump is not actually for our drinking water, it pumps geothermally heated water up into several ponds used for scuba diving. At least the pumping cost is much much less than heating water would cost with the millions of gallons of water we have.

 

Here's an old thread on this subject. It's long and goes a lot of different directions, but I think you'll find a lot of valuable information in it.

Prius as a power source
http://priuschat.com/forums/prius-technical-discussion/21773-prius-power-source.html

 

This was my first Prius modification:

Prius - UPS Project

Bob Wilson

 

I know the pump is 120V; it plugs into a standard AC outlet in the pump house. What I don't know is its power rating. I can find out easily enough, and would do so anyway before embarking on the Prius generator setup.

I think we saw that generator a couple of weeks ago when we were in Harbor Freight. I'd like something with more fuel capacity and more easily moved between our houses as needed -- hence the Prius idea.

 

Hurricane season is here!
A $40 inverter for emergency use would seem to be a no-brainer. Especially in coastal areas.

 

How efficient is the Prius ICE for making inverted electricity, as opposed to a generater designed to deliver 2, 3, or 5K watts? Our generater is only 25hp running on propane ... and a little more hp on gas. But it seems like the efficiency would be poor, from a car. The Prius ICE is most efficient at about 50mph, using most of its (what) 90ish HP.

 

For such an infrequent application equipment cost trumps efficiency. But someone running power tools or lawn equipment remotely probably should get a generator instead.

Non-Prius-specific question: how do you arrange a ground/earth connection for a generator or inverter when operating devices which have a grounding plug?

 

My apologies to Bob Wilson for lifting the data he provided, but I cannot find the link to it. Bob writes, ...

"My fuel burn rate at 1kW is also 0.25 gal/hr., or 4kW hr/gal. measured at 30-40F, worst case. This is also the original specification in the Northern Tool catalog for the "eu2000" at half load, 1kW, temperature unknown. So here is a survey of Honda generator specifications including the 1kW Prius hack:

1. 6.1kW hr/gal@5000W, 5.4hrs - EX5500K2A
2. 5.9kW hr/gal@2800W, 7.2hrs - EU3000isA
3. 5.8kW hr/gal@1600W, 4hrs - EU2000iA
4. 5.7kW hr/gal@900W, 3.8hrs - EU1000iA2
5. 5.6kW hr/gal@4000W, 7hrs - EX4500SXK1A
6. 5.4kW hr/gal@400W, 15hrs - EU2000iA
7. 4.4kW hr/gal@2500W, 7.9hrs - EX5500K2A
8. 4.2kW hr/gal@2000W, 10.5hrs - EX4500SXK1A
9. 4.1kW hr/gal@700W, 20hrs - EU3000isA
10. 4.0kW hr/gal@1000W, 44hrs - Prius inverter
11. 3.1kW hr/gal@225W, 8.3hrs - EU1000iA2"

Great work, Bob.

The wild card in this is that the Prius only needs to run when sufficient power is taken out of the HV battery, while a genset is running (albeit, at a reduced fuel consumption level), regardless of power draw. It's hard to draw an accurate correlation to a real-world situation.

 

76hp max from ICE. Atkinson cycle ICE is pretty efficient (around 35%) producing at above 15hp (very low 20% load).

When the HV battery is low, Prius charge the battery at around 21hp (I have observed around 1,300 RPM). At that rate, ICE would be around 37% efficient.

There is also HV battery charge/discharge loss. If the HV pack is 70% efficient then the total effiency is 26%.

I have no idea how efficient those Honda dedicated generators are.