Prius as a Generator Revisited

<div class='quotetop'>QUOTE(Ecojosh @ Nov 12 2007, 09:35 AM) [snapback]538457[/snapback]</div>

My question is why would anyone want to do this?
A small portable generator doesn't cost as much and doesn't put your $20,000 Prius unnecessarily at risk.

http://www.twistingwrenches.com/index.php?...oducts_id=15892

 

<div class='quotetop'>QUOTE(Ecojosh @ Nov 12 2007, 12:35 PM) [snapback]538457[/snapback]</div>

The inverter you've referenced seems to be the same inverter I've used. You cannot hook it up directly to the traction battery unless you include some reduction transformers or switchers. Output of the HV battery is 210-235 Vdc. You'll fry your inverter, which is designed to run on 12 Vdc. Go to this link:

http://priuschat.com/index.php?showtopic=22487&hl=

This is my old thread on this matter, and it contains a lot of discussion on both using the 12-volt system and the HV system. I doubt that you'll use a constant 1,500 watts of power, so using an additional battery on the 12-volt system may work for you. If you'll need more power, the HV system is the way to go.

 

<div class='quotetop'>QUOTE(Ecojosh @ Nov 12 2007, 09:35 AM) [snapback]538457[/snapback]</div>

I don't know how to put this,,but I think this is an idiotic idea!

First, the inverter you list, is a modified sine wave inverter with a capacity of 1500 watts. MSW inverters will kill most electronics with thier modified sine wave form

Second, 1500 watts is not enought to power anything but the smallest loads. No fride, no furnace etc.

Third, This inverter pulls its power off the starting battery, and as such this battery's capacity is tiny. That will force the car to run to keep up with ANY 120vac load you put on it. It is a VERY INNEFFECIET way to power anything.

Fourth, if you have the kind of power outage that requires you to feed the any generator day after day, do you think the neighborhood gas station will have power and therefore gas all the time.

As stated before, a simple honda eu series generator can be had reasonably, it is very fuel effecient and will run the average house if you are careful with the loads.

I would sugguest that you visit http://www.wind-sun.com/ForumVB/index.php ro get some education on DC power and inverters.

Having said all of this, there could be an argument to be made that if you could use the HV battery system of the car and the inverter built into the car you MIGHT be able to create a viable system. I think that having a standby generator instead 'though. I wouldn't, as haven been said before, risk my (wifes) Prius over such an endeavour.

Icarus

 

I don't want to go into all the details but much of the above (Icarus) info is wrong -- I don't know where he gets it. There are threads listed at the top of people that are doing this quite happily and for good reason. This is just so you don't get scared off if you want to run appliances from your Prius during outages.

 

Go to www.priups.com for an interesting read also.

 

How many hours of backup do you need?

I have a Honda EU2000i (4 stroke, power inverter), and I can get about 8-12 hours on a gallon of gasoline.

It saved my fridge full of food in yesterday's storm in the Bay Area, plus kept a few computers humming... Yeah, I could have also plugged in a 12V inverter in my Prius, but I rather keep the gas in my car for an emergency getaway, if needed.

Anyone know how many hours can you run a Prius on a 10 gallon tank in pure "generate 12V" mode?

 

Just to defend myself!

There are multiple threads on this subject here on Prius chat, so there is little reason to rehash.

In my other life, I design and build off grid solar electric installations. As such I know about batteries, inverters, and most importantly loads as they relate the sizes and designs of each.

The point is, you can indeed power limited loads with a 1500watt modified sine wave inverter from the Prius starting battery. What I have suggested however is that there are many better alternatives IF your goal is to provide emergency power for essential household appliances.


Icarus

 

I have powered a refrigerator with an APC SmartUPS 750 for an extended period during a power outage here in Florida. It would run mine, which was Energy Star rated, but it wouldn't run my mom's.

 

The following assumes gasoline's energy content is 33 kwh/gallon.

The generator specs tables I have collected for the Honda EU2000i says it'll run 15 hours putting out 400 watts on a 1.1 gallon tank at 16.5% efficiency. At 100% load (1600 watts continuous) it'll run 4 hours at 17.6% efficiency.

The Prius, outputing 400 watts for the user, plus its internal 315.8 watt idle load, should run about 73.53 hours on a 10 gallon tank (assuming there is no reserve tank capacity).

Here's the full table that I made in Excel, based on numbers from bzwilson's tests. The idle and user loads are in watts. (The car's own equipment burns the equivalent of 315.8 watts). The 10kw load is listed only for efficiency comparisons...I do not know if the Prius can actually sustain a 10kw load while parked without additional airflow/cooling over its electronics. Overall efficiency will be higher if you can insert a larger buffer battery, so that when the engine does come on, that the charging load (i.e. user load) is around 2kw to 5kw, suggesting efficiency of 14-15%. This efficiency is comparable to conventional Coleman generators at 50% load. (It is lower than the 18% efficiency of Honda generators at 100% load.)

Here's a table I made in Excel, based on numbers from bzwilson's tests. The idle and user loads are in watts. (The car's own equipment burns the equivalent of 315.8 watts). The 10kw load is listed only for efficiency comparisons...I do not know if the Prius can actually sustain a 10kw load while parked without additional airflow/cooling over its electronics. Overall user load efficiency will be higher if you can insert a larger buffer battery, so that when the engine does come on, that the charging load (i.e. user load) is around 2kw to 5kw, suggesting efficiency of 14-15%. This efficiency is comparable to conventional Coleman generators at 50% load. (It is lower than the 18% efficiency of Honda generators at 100% load.)

Code:

kwh/month | Idle | User | Total | Tank  | Runtime | Burnrate | Real kwh | Real       | User kwh | User Load
=avg base | Load | Load | Load  | (gal) | (hrs)   | gal/hr   | Produced | Efficiency | Produced | Efficiency
load      | watts| watts| watts |       |         |          |          |            |          |
 
  72        315.8    100    416    10      126.58     0.079     52.632     0.15949     12.658     0.038
 180        315.8    250    566    10       93.02     0.108     52.632     0.15949     23.256     0.070
 360        315.8    500    816    10       64.52     0.155     52.632     0.15949     32.258     0.098
 540        315.8    750   1066    10       49.38     0.203     52.632     0.15949     37.037     0.112
 720        315.8   1000   1316    10       40.00     0.250     52.632     0.15949     40.000     0.121
1080        315.8   1500   1816    10       28.99     0.345     52.632     0.15949     43.478     0.132
1440        315.8   2000   2316    10       22.73     0.440     52.632     0.15949     45.455     0.138
1800        315.8   2500   2816    10       18.69     0.535     52.632     0.15949     46.729     0.142
2160        315.8   3000   3316    10       15.87     0.630     52.632     0.15949     47.619     0.144
2520        315.8   3500   3816    10       13.79     0.725     52.632     0.15949     48.276     0.146
2880        315.8   4000   4316    10       12.20     0.820     52.632     0.15949     48.780     0.148
3240        315.8   4500   4816    10       10.93     0.915     52.632     0.15949     49.180     0.149
3600        315.8   5000   5316    10        9.90     1.010     52.632     0.15949     49.505     0.150
3960        315.8   5500   5816    10        9.05     1.105     52.632     0.15949     49.774     0.151
7200        315.8  10000  10316    10        5.10     1.960     52.632     0.15949     51.020     0.155

Related links:
http://hiwaay.net/~bzwilson/prius/priups.html

http://www.priups.com/others/index.html
http://www.priups.com/
http://www.priups.com/sitenav.htm
http://www.priups.com/misc/update-2005-06-1.htm
http://www.priups.com/misc/update-2005-09-2.htm
http://www.priups.com/misc/update-2007-12-31.htm
http://www.priups.com/misc/multisupply.htm

http://priuschat.com/forums/prius-modifications/12430-priups-using-prius-backup-generator.html
http://priuschat.com/forums/audio-electronics/37760-using-prius-backup-generator-any-changes.html
http://priuschat.com/forums/prius-technical-discussion/35513-prius-whole-house-generator.html
http://priuschat.com/forums/prius-modifications/39613-prius-generator-revisited.html
http://priuschat.com/forums/prius-modifications/39613-prius-generator-revisited-2.html

http://autos.groups.yahoo.com/group/toyota-prius/message/97207

Have a good day,

-hk

 

Wow! Thanks for the detailed calculations, hkazemi! :welcome: Welcome to PriusChat!

 

No problem! (Thanks for the welcome).

I actually did these projections last August, but now that I saw a relevant thread here I figured I could share them. I personally think the PriUPS concept is a great one...no more noisy, hard to move, hard to refuel, unmaintained generator taking up space in a garage that is only intended to cover the rare power failure (a few hours per year, but possibly up to a few days). Not to forget that buying a generator during a power outage becomes very difficult as demand shoots straight up.

For similar overall efficiency, long runtimes, a relatively clean running engine, and relatively high power output, this is a solution I think deserves more exposure.

A related concept is the V2G (vehicle to grid) technology that is being pilot tested by Xcel Energy in Colorado. I saw one of their PHEV Ford Escape Hybrids here at the Living Green Expo. The same inverters used in a V2G vehicle could also be used to power a house.

Finally, a PriUPS is basically the complement to a PHEV. When your car needs charging, you plug it into the house. When your house has no power (utility failure or PV battery storage is depleted), you can run it from your PriUPS. One complements the other!

 

Toyota has hinted that a PriUPS may be a future development. I hope they introduce bidirectional power transfer in the LiION PHEV Prius when they start shipping!

 

I was thinking of buying a Europe inverter that has 230 volt in to 12 volt out. Then use another USA 12 volt in 120 volt out inverter. The problem I see is Europe has 50 cycle power to our 60 cycle power. Has anybody tried this?

 

You'll lose some efficiency and generate some heat using two inverters in series.

50 Hz versus 60 HZ shouldn't be an issue. The 230v input will be DC (I assume you'll hook directly to HV battery) and the 12v output will be DC. Only AC would be from USA 12vdc in to 120vac out.

230v in (AC or DC) to 12vdc would be called a 12vdc power supply, if it's AC input, and DC-DC converter perhaps if DC input. But I presume you'd be looking to use a device that's MEANT to AC input, but you are using it with DC input.

It doesn't need to be "European" if it handles 230v input. Many AC products work with both 120vac and 220-240vac based on switch setting.



Anyway, I'm still looking for the "perfect" HV inverter that takes 200-240vac or vdc and converts to 120vac and/or 240vac at 3-5 KW. I'd prefer to buy something good and new, and I'm sure others would love to find such a beast too.

 

Ask a simple question and get a bunch of negative posts flooding your thread.

Welcome to PriusChat!

I just did what your asking and it WORKS GREAT!! Oh and it runs everything from my fridge to my laptop and they dont burn up. I ran my laptop for 3 years with a modified sine in my truck and no issues.

http://priuschat.com/forums/prius-modifications/47346-110v-outlets-your-prius.html

 

Just a note to readers: the device is an 'inverter' not 'inventor'. An inverter is specifically a device that converts DC to AC. A rectifier converts AC to DC, and is a core component of a standard power supply.

The PriUPS project, PriUPS-getting electricity FROM your hybrid vehicle, uses a combination of switching power supplies that are designed for 200-240v AC input (but are DC input compatible) and have 12/24/48v DC output. Their output is then is connected to the 12/24/48v input of an inverter that is designed for extended runtimes (like what might be found in middle and upper end data center UPSes).

More:
PriUPS update 08 Jan 2006 http://www.priups.com/misc/switcher-examples.htm

List of systems (800w to 2.7 kw):
Portable Priups: Several Examples
Portable PriUPS - Large
http://www.priups.com/misc/r3x-photoessay/

Two ways to go even larger would be to have two of these systems sitting next to each other, or instead to find even higher capacity switching power supplies and inverters. The advantage of two smaller systems is you can shut off one of them completely if your load falls enough, while the advantage of the larger single system is being able to start and run even bigger loads. Another thing to keep in mind is that your standard household AC outlet is rated for 120v 15 amps = 1800 watts = 1.8 kw and a 120v 20 amp outlet is rated for 2.4 kw. If more than 2.7 kw of 120v power is needed, multiple sets of power supplies-inverters would probably be a very good idea.

 

For those of you who are still interested in this, there has been a significant change in the solar power industry since the PriUPS articles were written. The change is wide availability of inverters designed for "grid-tied" solar systems. With off-grid solar power the voltage is kept to battery voltages and is normally somewhere from 12 to 48 VDC. The panels charge the batteries directly.

With "grid-tied" systems their are no batteries, the panels feed the utility grid through an inverter. So, the panels are generally connected in series so the currents (and thus wire sizes) can be kept small. This results in DC voltages from 200 to 500 VDC. There are then special inverters just for this application. They're not cheap ($2000+), but they match up with the Prius HV output perfectly. They also tend to have the necessary switching setup to isolate the grid in the even of power failures, while keeping the juice on in the house if the sun is shining.

My house has a grid-tied solar array. We use a SunnyBoy grid-tied 3000W inverter. During the day, when we're at work, it supplies power to the utility (amongst other things, a very clean sine wave). At night, we pull power back out of the grid. Since we have time-of-use metering, we get more power from the utility than we put in, because we put power in during peak hours and take it out during off peak hours.

Where does the Prius fit in to this? The inverter is designed to accept 200-500 VDC input and put out 120/240 VAC single phase (standard US power, Euro models are available too). So, if the power goes out and the sun is down, where can I, a Prius owner, find 200 to 500 VDC? We have a DC hookup in the garage into which I can connect the Prius. Open the garage door, turn on the car, and I have ~220VDC going to the inverter, which is designed for exactly that purpose (I had to adjust the inverter slightly, it defaults to starting conversion at 228 VDC, the Prius voltage is sometimes just below that level). The house gets powered, everything is hunky-dory.

For reference, here's a spec sheet:

http://www.mrsolar.com/pdf/sma/SB30004000US.pdf

(I'm not affiliated with this company, nor do I particularly recommend them, they just had the data easily accessible. If you want to do something along these lines, Google "grid tied inverter" and start wading).

Don't know that I'd suggest it to someone who doesn't already have a solar array (a generator would cost a lot less), but it sure makes a nice setup. Since I own a Prius and a solar array... Only used is a couple of times, and only for a few hours each time (the utility is pretty reliable), but, it only cost about $300 to run the wires from the garage to the inverter and to install a connection point on the Prius.