Power Your Home With a Prius

Boats and RVs have dealt with this for years. The normal solution is to use a transfer switch which connects the ground to ground when on shore power, but connects the ground to neutral when running from the onboard inverter. No resister is used, since this would constitute a safety hazard.

Tom

 

I have a diy 1kw (1.5 peak) sine wave system that works fine for oil burner, radiant heat and wood stove input pumps, tv, and computers. It would be nice to have 240 v for our well, and more power for a microwave. Grid power disappears for up to 3 days several times a year.
Some experience/suggestions:
The #4 wire is what I am using, but keep it short - it might have up to 80 amps or so, peak. I have an in-line fuse (but intend to substitute a dc breaker) to protect the Prius 12 v fuse (probably awkward and expensive to replace). I have an Anderson connector set, not yet installed.
Our Prius is in an attached garage, with an exhaust hose to the outside and CO alarms in the residence.
Do not isolate by turning of the house master switch and then "reverse plugging" into your regular house circuit! Too much chance of endangering yourself and others. Use proper backup generator switch/breaker setup for critical circuits. I am using extension cords so far, pending higher capacity Prius arrangements.
We forgot to turn off the heater in the Prius once, which resulted in a much too warm garage and a close to empty gas tank.
I used this setup to run a corded electric weed whacker, but decided that a cordless whacker is much more convenient for my needs.
A dealer check of the original 12 v battery indicates that it is still in good condition (150,000+ miles).

 

I know, Tom . . . but when your generator is on a trailer (for charging your car, for instance) ... you don't have the luxury of a transfer switch . . . . and I know neither you or I feel like driving a 5/8 copper stake - six feet into the ground, so that your transfer switch is properly grounded.

humor aside ... is ground that's wired to neutral on a generator that's sitting on a (rubber tire) tailor truly grounded? I'm just saying ... ground to neutral versus ground to neutral via a resistor isn't much better. Fact is, some of my 'ground seeking' ... 'ground demanding' electronics would still not be satisfied unless it really really believed it was truly grounded. The resistor did the trick for me ... and tying the ground to neutral would not. It's like needing 120V power outdoors on a GFI. Sometimes GFI's are so sensitive that they'll trip, due to 5 ohms of ground fault resistance being lost somewhere ... but not where it matters. You can fret over it ... or you can run your 120V GFI through a 1 to 1 isolation transformer and get on with your task. Not advisable if you don't now what you're doing ... but if you do, you can save the day.

.

 

If you want a quick and easy ground, you might consider a metal screw in stake (used for tying down pets, tents, airplanes, etc.) or clip onto a metal (preferably clean, e.g. galvanized) post, such as a fence post, that's already in the ground. Not what code would require for a building ground, but something simple like this should prevent a (static) charge buildup on your generator sitting on a rubber tire vehicle, especially if you have damp ground that conducts reasonably well. Or, if you're near a building, you could fabricate a ground connector to a nearby outlet (and the building ground). Take a standard "replacement" grounded power plug, and connect the ground pin only, with a single wire, to ground on your vehicle or generator (this probably actually doesn't meet code, since your generator under a fault condition might supply more ground current than the outlet is intended to handle - it normally only needs to handle the current the breaker at the panel can provide).

I think either of these would be better though than tying the generator's neutral to ground, either directly or through a resistor.

And I was acutally considering using an isolation transformer (which I already have) to power my heating system, since I'm not sure if a transfer switch (I don't have one yet) switches both neutral and hot over to the generator, or the hot wire only. If the latter, this could create an unintended short between my inverter's neutral and ground through the neutral and ground paths back to the service entrance. This could create havoc if I have a GFCI at the inverter.

 

I know this is an old-ish thread, but where/ what exactly are people buying for the 'exhaust hose'?

Of course we'll run use it with a CO alarm too and never overnight

 

Our car is at least 30 ft away from the rear door so I don't bother. However, I believe JC Whitney and Northwest sell exhaust hoses.

Personally, I've been thinking of an old, gas water heater and rigging up the exhaust to flow through the firebox. It might warm a couple of gallons making a sponge bath less 'brisk.'

Bob Wilson

 

Thanks Bob. I did not realize they are made of a plastic, but can stand up to 600F: http://www.carguygarage.com/2exho.html
Clamping the hose on securely etc seems a pain/ slightly risky. After sleeping on it I think we'll leave the car outside with a Disklok on + the key inside the house. http://www.amazon.com/gp/product/B0071NQ11G/

Those locks can be angle ground off and a thief could drive it away if left 'running' but we'd likely hear them angle grinding + this setup should be fine for camping too. I'd rather risk a stolen car than CO poisoning

 

As a rule of thumb, anti-theft only has be better than the neighbor's . . . cruel as that might sound.

Jack up the car, remove a wheel, rest the car back on the tire, leave the jack in the car, and take the lug nuts into the house. <GRINS>

Better still, just remove the lug nuts from one wheel, leave the lug wrench in the driver seat and take the lug nuts into the house. <LOL>

Bob Wilson

 

I used inverter for the 12v battery to use on a camping trip years ago. I felt a little bit nervous that I could have potentially been causing harm to the car. I did speak to my Prius mechanic and he said that it is not good for the car to leave it running for long periods of time without moving it. He gave me the technical reason, but I can't remember a single word he said. So my question is, can my Prius get damaged if I use it as as a generator?

 

Also, any guess on maximum run time?

 

This was my first version: Prius - UPS Project

In 2011, we camped out in the house four days and six hours without a problem.

Bob Wilson

 

Who's the daddy?

 

Had a summer job in the lab at a nitrocellulose plant. Every hour, we took a truck on a near 2 mile loop of the site collecting samples. Sometimes we forgot to turn the truck off, and it sat idling for an hour. Didn't seem to cause any harm.

From a quick search, it seems idling a car for too long results in it running cooler than if it was driven. This means higher emissions, and the potential of carbon build up in the cylinders, but the issue likely to lead to damage is that more fuel can accumulate in the oil and thin it out.

These issues apply more to a straight ICE car than a hybrid. A Prius used as a generator isn't actually idling the entire time. It powers the inverter off the traction battery. when the battery charge gets low, the ICE is fired up to recharge it. During this time, the ICE is running under a heavier load than what a non-hybrid one is while idling. This means more heat to hold off potential idling issues. A gen3 might have its EGR valve clog up quicker.

I can't say no issue will develop from 'idling' a Prius for extended periods of time. Unless the car is idling for days upon days, and only driven to get more gas before idling for days again, I won't worry about it.

 

I love the fact that our Prii can afford us close 1KW of electricity (with a proper inverter). I will definitely be on the lookout for a reasonably priced pure sine wave 1KW inverter to just have in the trunk. However, for the emergency house use, there are better, cheaper and probably more efficient solutions on the form of inverter generators. I just picked up a 2KW (peak, but had no problem running a 1700 watt heat gun I tested it with) inverter generator for $350. It weighs 40 lb (with a full tank of gas), provides pure sine wave output, is quiet and very economical since it does not run at constant speed (of about 3600 rpm, as non-inverter generators do). It spins up and down corresponding to the load and is designed to be "stacked" with another one just like it to double the power if needed. The only thing it lacks is split-phase 240V output, so it wont's run 240V loads all by itself. A step-up transformer may be necessary of you need to run a well pump or such.

Hope that helps to those looking to spend over $500 on the Prius 12VDC - 120VAC setup for the house use.

P.S. I did install a 30A transfer switch in my house, so as not to have to back-feed or run extension cords.

 

I would recommend sizing one for 1.5kW because the 12V battery can provide 10s of seconds of surge sometimes needed for loads like motor startup that quickly settle down. It should have a 12V battery voltage monitor and/or power output meter.

The "surge" rating is only good for a couple of 100 ms, not even enough to handle some inrush loads.

Bob Wilson

 

@V8Cobrakid. Can you please post your setup briefly? I'm considering powering my house, when there isn't power from the grid.
I have a 1000W 12V inverter laying around, and some pack of Prius and Camry battery packs.

Thanks so much for the anticipated reply

 

Please do you have a setup for house arrangement?

 

What do you mean "arrangement"? You connect the inverter to your Prius 12V battery and the output of the inverter to the house. That's the basic arrangement. If you need details on how to connect things, do a google search for "Prius as a house generator". There are lots of videos and tutorials on the subject. The idea is that you hook up your Prius' 12V battery via inverter to power your house and leave the car in READY mode so it can fire up the engine to charge the 12V battery as needed. This is a very neat idea and works well as the Prius 12V battery can supply about 1000 watts of power.

The connection to your home needs to be considered carefully because if you do it wrong (and there are ways to do it wrong, such as back-feeding the house from the alternate source and not disconnecting it from the utility line) you can put linemen working on your power lines during an outage at risk. The real proper way is to install (or have installed by an electrician) a transfer switch that will be fed with alternate power source (Prius or generator). That makes sure everything is safe for everyone involved. These switches are pricey and if you are not handy with home electrical wiring installation can be pricey too. I just installed a 10 circuit 30A 240V switch on my house. The switch cost just under $400. I installed it myself as I was doing work around the house electric panel anyway and I know what I am doing with such things. Now I can connect just about any source of electric power up to 7,500 watts to that and I have 10 circuits I chose from my main panel to be able to switch over from the main panel to the alternate source. I chose things like refrigerator, oil heating system, my pellet stove, some outlets around the house to charge phones, my internet electronics.

After carefully examining the expenses to make my Prius a source for home power I decided to go with a 2000 watt inverter generator (different than a conventional generator. Much quieter and more efficient and puts out pure sine wave AC power) by Champion (got it used for $350) instead. I good pure sine wave 1000 watt inverter will run about the same and there are more things needed like fuses, cables, etc. and it will still provide less power than the generator I bought. This was my personal decision, of course and for others Prius may be the way to go. It certainly is a very good way to have 1000 watts handy and I may still set the Prius up for it.

Hope that helps.

 

Heheheheh! It sure PERFECTLY helps.
I'd consider your kind of setup also(20A, 240V) located installed to be installed in the house.
I already have a 12V, 1000W inverter for the setup.

Thanks so much.

Dxta

 

Which one is more reliable and CO safe:

• Prius runs daily, catalytic converter - provides 1kW by adding an inverter
• Home Genrec self-test once a week, external pad - provides 16kW with transfer switch
• Portable generator, where ever - provides 2-7kW

Every year when the cold weather arrives we read about people who run their 'portable generator' in the house and kill the family. Granted we're Prius people, much brighter than the average bear. Just it is a real risk.

Bob Wilson