Using PIP As A Generator

current is measured in amperes, Voltage is the force required to allow the electron flow thru the circuit, load or resistance.

 

that's more logical TY

 

After reading these and other comments and talking with an electrician and with an engineer, I am now looking at designing a PiP system that will hook into my SunPower PV SunPower inverter in the house. It is already DC-to-AC (PV to circuit breaker panel). The transfer switch can be manual. In addition, I am thinking of the possibility of recharging the PiP during the daytime from the up-to-now wasted DC output of the PV panels while the emergency power outage lasts. Logically, the components are present. It's a question of balancing everything out and connecting it safely and easily when the need comes. I do not mean to replicate the 2007 PriUPS setup as in "uninterruptible power supply", but to provide the power necessary for minimum house functioning, i.e. the fridge, the natural gas - fueled tankless water heater, the natural gas - fueled range, one receptacle for cell phone charging and a radio, and maybe even powering the ground-sourced heat pump my house has. The GSHP might be a bridge too far, as there is a compressor/pump involved.

More to come... thanks for the ideas in your posts and for USBSEAWOLF's diagram.

 

Gotta get me one of those big Tim Allen-style inverters from Hope Depot or equiv.
I got a teeny tiny one for running off AA batteries...for the new Electroluminescent (EL) wires.
It sounds like any Gen2 or Gen3 or PiP can use the inverter option?
Is there any reason Gen2 should get smaller wattage inverter vs. PiP?
That is the first simple step.
I thought Bisco had a good idea to hook onto the under hood + terminal

 

You are correct, there is nothing special or different about the PiP in any of this discussion. Here's how it works:

The inverter attaches to the small 12V battery. You put the car in Ready mode (ignition on, ready to drive). Now the 12V battery powers the inverter. This will quickly kill your 12V battery, but the Prius' large hybrid traction battery automatically recharges the 12V battery. When the charge on the traction battery gets low, the gasoline engine automatically starts, which very efficiently charges the traction battery. Once charged, the engine switches off. This cycle continues until you switch off the inverter or you run out of gas, which can take days.

What about wiring directly to the traction battery? Apparently, it can be done, but it's quite expensive to convert into household current.

 

What do you see as the advantage of that?
The disadvantages I see are:
1) It is temporary.
2) The length of cable is increased, causing more resistance losses.
3) It would probably require the hood to be open.

 

Different types of motion here; the generator must maintain constant speed whereas the Prius is trying to maintain as close to constant torque as possible

The Prius lasting two days came from El Dobro who said

“Prius owners in Japan were using Prii as generators after the eartquake and tsunami there. That's where Toyota got the idea. The cars usually ran two days on a tank of gas.”

I am not bragging I am simply telling you roughly how much gas I used during a 2 day period the last time I powered my house on my generator. The reason your math doesn’t work is the following:
The generator is not giving 5,000 watts for 24 hours a day; that is the power available. During times of little to no load all it needs to use is enough gas to keep the engine and generator spinning at the proper RPMs. When load is demanded the throttle opens to provide the necessary power.

Quoting Jimbo69ny


“3. Hopefully the EVSE would have automatic switching so when the power goes out it automatically reverts power back to the house to keep you going. Meaning you dont have to go out into the cold and try to get a generator to start.”

Which brought me to my point if you want the Prius to automatically start powering your house when the power goes out you need an automatic disconnect from the mains or you will kill someone

So I left out Carbon Dioxide, both will kill you. Going back to the quote from Jimbo69ny; if you are asleep and the power goes out, and your Prius starts powering your house, and the engine starts, do you want to rely on the fact your garage is supposed to be airtight and sealed from your home?

As I said earlier I was without power for a week and only had 1,000 watts available; it was not enough. I don’t use 3,600 KWh per month. These loads are intermittent. For those of us that live in rural areas; we don’t have natural gas to cook with or heat our water; we don’t have city water, I have to pump it up out of the ground; we are miles from the nearest store so we have a lot of food stored in our refrigerators and freezers. I also have a wife, two children, a dog, and a cat to feed.

Of course if you are alone, don’t bathe, and only eat granola; I suppose 1,500 watts is fine

My water heater, dryer, and stove all use 240 volts. Most generators that are 4,000 watts or higher offer a 240 volt output; which I plug into a socket on the outside of my house and send to my electrical panel. I shut off the mains and engage the breaker to my generator and the whole house is powered. I don’t have to keep running around plugging in things for a couple hours, then unplugging them to plug something else in for another couple of hours. I can move the power from one thing to another, when I need to, just by using my breaker panel. Trust me, after a few days you’ll be begging for a warm shower and clean clothes. If I was on the Jersey shore right now, I would want my generator for power. Some of these folks will be without power for weeks. After a week without power, limited to 1,500 watts, I am willing to bet you will be thinking the same thing.

Lastly, someone mentioned hooking an inverter to the traction battery for more power. Remember the traction battery is not a 12 volt battery and will destroy your inverter.

Look I’m not saying you can’t use your Prius for power in an emergency if you want to. I am only saying that it is not the ultimate home generator that lensovet declared when he said this:

“This would be the cleanest, most fuel-efficient generator on the planet!
First, though, you'd need to figure out how to get the engine to charge the battery, even without drawing juice.”

A Prius is designed to take you from place to place as efficiently as possible. A generator is designed to produce electricity; they are different.

 

Although true, the state of the art Atkinson cycle 4 stroke engine with catalytic converter is superior (in term of efficiency and emission) than a generator with Otto cycle 2 stroke engine.

 

Since apparently I'm partly at fault here, let me qualify my statement by saying "…for the majority of people in this country". Because the majority of people in this country do not live in rural areas with no natural gas or central plumbing/water supply systems and don't need to start running their dryers in the middle of power outages.

 

The idea of having a dedicated generator is nice. On the flip side, you'll have to maintain it as well. Oil and filter changes? Spark plugs?

Having Prius as a generator, you can bet it'll work when you need it.

 

There are several advantages
1. Length of cable, 110V would be shortened. Because
2 I would be driving the front of the car in, as the cabling would be very close to a main wall outlet.
3 hood would not have to be open, as cabling can be snaked thru front grill. Or leave hood open, so what?
4 Not necessarily temporary, cabling can be left in place or removed for next emergency, your call.
5 In my situation, it would be perfect, with attached garage.
6 Normally I back in, but I can adjust.
7 driving in forward allows me to leave my garage door open a couple of inches for the exhaust.

 

AC travels much better than DC, especially at the same wattage. So generally you want AC cabling rather than DC cabling. Look at the difference in thickness between an extension cord and jumper cables for a visceral example of this.

 

Both are using exactly the same type of motion. Optimizing is a completely different subject. And when the Prius is charging it is trying to do that as efficiently as possible.

Of course it does. Which is why the Prius with its larger latitude for throttle settings is more efficient. Again.

It was probably your use of the word 'fantasy' to describe the need for a perfectly normal electrical switch (which would be needed regardless of using the Prius or a generator), that threw me.

It won't unless the car is actually TURNED ON.

I live in a rural area, and have no natural gas, or town water. On the other hand, I am adept at living within my energy budget, while not insulting others.

I have survived in my house for 3 weeks (3 seperate occasions within 1 month) with NO power, and yes, I was begging people for showers. Which is exactly why I got an inverter for my Prius.

Nonsense. One merely needs to get an inverter designed for the DC voltage of your traction battery. Solar inverters are the best bet.

And it is. If you want to show otherwise, you need pollution numbers and efficiency numbers.

 

Yes the Prius engine is remarkably efficient for transferring energy to the cars wheels and propelling you down the street, but what everyone seems to miss here is that it is not efficient at transferring electricity to the 12 volt battery you are plugging your inverter into. Most of the charging of the traction battery comes from the regenerative braking, not the gas engine, and while the gas engine can send some of its unused horsepower to the battery, that is not the most efficient use of the engine. The Prius engine must spin one of the motor generators through the transmission to generate electricity. This electricity comes in the form of high voltage AC current, which then must be converted to high voltage DC current to charge the traction battery; it then must be converted again through a DC to DC converter to take it from hundreds of volts down to the 12 volts that power the cars electronics. At this point you come along and convert it again from 12 volts DC to 120 volts AC for your emergency power, losing efficiency at every conversion. There is another concern here too, when you draw power from the cars 12 volt system, the car must replace it from the traction battery through the DC to DC converter. What is the power limit of the DC to DC converter? The Prius was not designed to produce massive amounts of power for the 12 volt system because all that the 12 volt system does is charge the relatively small 12 volt battery and power the cars electronics. Before people start trying to draw more than 1,500 watts you better make sure the DC to DC converter can handle the load, or you are going to be replacing a very expensive part of your car.

The generator’s engine on the other hand, spins the generator which sends out 120 and 240 volts AC current directly, without the need for all these conversions and thus is far more efficient for the task it was designed for.

 

I can't say about the load that 12V system can handle but the efficiency is better than the generator. See my previous post. Even with the charging/discharging loss, it is still more efficient.

Prius engine can stay in peak efficiency all the way from 10 kW to 50 kW. Generator's Otto cycle will suffer in partial load.

 

You still seem to be missing the fact that the small loads require the generator running at some minimum RPMs. 1000 RPMs to charge a phone is complete waste. Yes, as has been mentioned many times, 1500 W is about the max from the ACC battery, beyond that one needs to tap the traction battery. I am not sure where you got the idea that it matters in the least how the batteries are charged while driving normally. When the car is parked the parking pall is engaged, fixing MG2, thus all the power is going to MG1, and charging the battery. Where do you think that energy is going to result in an efficiency loss? Sure there are conversion losses, as with everything, but the Prius engines starts at 38% efficiency. Portable gas generators are closer to 25-30%.

 

And what precisely is the efficiency curve of the Prius gas engine when all it is doing is sitting there charging the traction battery

How is using a 100 HP, 4 cylinder engine to produce 1,500 watts more efficient than using a 5 HP, single cylinder engine to produce 5,000 watts?

What threw me was the poster’s idea that his car would just power his house all by itself, thus the word fantasy.

If that is the case, how will your car power your house without the need of you to doing anything? Thus not what the poster suggested

I’m sorry, but I find people who do not bathe on a regular basis to be insulting.

Thus you prove my point, although I’m not sure how you get a nice hot shower out of 1,500 watts.

If you are going to go that far why not just put in the solar panels and a wind turbine and be done with it?

How does pollution have anything to do with efficiency? Besides, I’m not running my generator every day, it’s for emergencies, and if it sends out a few more pollutants for the few hours I use it, so be it; it still uses less gas, and I can use my car while my family stays home with power.

 

Unless you are tapping the traction battery this is meaningless.

 

PEAK efficiency, of course, unlike your generator which needs to load match.

By being OFF most of the time. It amazes me that you don't seem to have gotten that yet. Energy = Power * Time.

Which is what makes your sly reference about others, insulting.

An excellent question, that I ask people every day. Most don't have a good reason not to.

Read the quote you were responding to.
And still you haven't shown how it could use less gas.

 

How many percentage should we take off for the traction battery 200v DC to 12v DC converter? If it is below 39% loss, Prius is still more efficient. You see, the gap is to huge.