Hybrids for emergency power

[gikard]

Has anyone considered running the inverter off of the ~270 V high voltage traction battery instead of from 12V? Some solar power inverters may accept the traction battery voltage. What's its voltage range anyway?

[bwilson4web]

Originally Posted by gikard

Has anyone considered running the inverter off of the ~270 V high voltage traction battery instead of from 12V? Some solar power inverters may accept the traction battery voltage. What's its voltage range anyway?

The one's I've read about used the NHW20, 04-09 Prius, and the 200V traction battery feeding a modified 3kW, UPS inverter. I've exchanged e-mails with Richard and his is a serious project.

I've seen excellent progress with the solar panel inverters but the last time I checked, they were still fairly expensive, several thousand dollars for 3kW inverters. There is a lot of work going on in this area and if I wanted a turn-key system, I would search harder. But price remains a problem and the too frequent use just for emergency power.

Anther interesting development has been in the inexpensive, 5-6kW, gas generators. One of my co-workers bought a Coleman unit for ~$350 which is impressive since in addition to the gas engine there is the power electronics. Of course they have the advantage of being able to switch the high-frequency alternator to synthesize 60 Hz. But again, these are being sold as dedicated, emergency power.

My current investigation is looking at the 33 kW, MG2 inverter that is water-cooled and already integrated in the car. When parked, MG1 can continue to provide power up to 18 kW and just needs a fuel supply, say natural gas. These are the NHW11, 2001-03 model Prius and can be bought for ~$5k. If done right, the Prius can plug-in to the house to generate power and later still deliver +50 MPG. Add hot water heating and possibly space heating, we're talking a mobile, co-generator.

Bob Wilson

[m11939]

In 2011, we have been hammered with Irene and Lee and a spooky Halloween weekend snowstorm up here in the Northeast. Each has caused its share of damage and power outages. I was lucky and only lost power for about a day and a half where I live during Irene. But during the snowstorm, many folks in CT and MA were without power for a week or more. All of this has got me thinking about backup power systems.

I have a 5000 watt generator which until this year, I have never really had to use. I connected it during Irene so I could pump water from my deep well and run my refrigerators and otherwise live normally. However, I quickly learned that the thing is a complete gas hog, using upwards of a half gallon an hour under low loads. It's also a bear to set up. I need to roll it away from the house on an unpaved driveway and over a lawn to get it in a safe spot to run it. That is quite a struggle and I'm not getting any younger. I figured there has to be a better way.

Searched the font of knowledge and discovered Bob Wilson's well documented inverter system in his 2003 Prius. Decided to give it a try on my 2010 Prius as I too happened to have an inverter (Portawatts 1750). However, I only tested it with a small load...about 300 watts. I just wanted to see for myself what would happen and indeed, the car ran every so often as I tested the power for about an hour to running my laptop, TV, CFL and regular fluorescent lights and other small loads I might want to use during an outage. All worked great!

OK, so I had my little power "appetizer" but now I too would like to have heat in a storm as a next step. Using an Amprobe, I determined that the furnace's largest load was when it starts the 1/2 HP blower motor, 10 amps for a few seconds. Then, the load drops off to about 6.5-7 amps for the remainder of the heat cycle.

Checked the fusible link in my Prius and it says its 140 Amps...not 100. (I took a pic but as a new poster, the forum won't let me post it.)

Tried to find out more info about this on the Internet but have had no luck. My guess is that the 2010 Prius' DC to DC converter can provide more power than the 2003's but I want to be sure. I would need about 1200 watts for a few seconds to start the furnace blower. That would be 100 Amps at 12 volts. This is more than Bob could get during his 2003 heater load test. (Bob: BTW, what does your 1/3 HP furnace motor draw when it starts?)

I've also got a 700 watt rated microwave that draws about 9.5 amps for about 1140 watts. It certainly would be nice to be able to use it...when the furnace wasn't on, of course. Again, 1140 is more than Bob could get with his 2003, but IF I have 40% more with the 2010 (1400?), maybe I'm not getting too greedy.

I like the idea of only using as much gas as I need and not really having to set the thing up. I mean, I park the Prius 10 feet from the house normally. During Irene, there was no way I could easily set up the portable generator during the storm. The rain was coming down sideways...for hours. The generator and I would have gotten drenched. But if my Prius had an inverter mounted in the back like Bob's, I'm sure I could have found a couple of dry minutes early on in the storm to connect a cord and run it into the house. Juice!

As Henry Petroski has pointed out many times in his books, "There is no perfect design". Using the Prius for something it wasn't intended has its limitations and risks. However, putting it to work on an emergency basis for light loads has a lot of appeal to me. I have no plans to sell "the monster" but I'd sure like to use it a lot less...maybe a couple of times a day for 15 minutes or so to take a shower or do the dishes. It would be nice if the rest of the day I could have peace and quiet...and save gas!

Anyway, if anyone can shed any light on whether the 2010 Prius indeed can provide more power from the DC to DC converter than the 2003, that would be great. Also, if anyone else has setup their Prius the way Bob has and has any experience with either running a 1/2 HP furnace motor and/or microwave oven with it, I'd like to hear about your experiences. Thanks.

[dcb]

Worth noting that some battery storage for your generator and a relatively simple controller would smooth it out pretty well too, and let you use your prius as a car during emergencies, and generally allow you to use a smaller generator if your loads a peaky (and allow solar/wind input as a potential contributor)

Hard for me to get excited about something so specific to one vehicle, since there are plenty of vehicle specific forums. Out of thousands of vehicles in the EM garage, 54 of them are priuses.

Also hard to get excited about it when it is solely for emergencies, if you are having enough emergencies that this would make a significant difference in the cost/quality of life then you might want to do some re-evaluating

[bwilson4web]

Hi,

One option is to replace the 12V battery with one having a higher "CCA" capacity which sad to say, I don't really know what the OE rating is even after service. But there are a number of alternatives.

I used a resistance, space heater, an especially well behaved load, to stress test the NHW11 inverter. What I observed was a voltage roll-off as the current increased. But you are at the cutting edge.

Now I contacted the vendor of the inverter I plan to use for my wife's ZVW30 and it has a 34 cycle, window for overload, before the current limit protects the circuit. You may want to investigate what your vendor claims.

For my wife's car, I have a high current, circuit breaker bought for RV application. The dataspec indicates it should trip before the fusible link. I'm at a conference but it is rated under 140 A so I'll get a faster action.

GOOD LUCK!
Bob Wilson

[m11939]

Thanks a lot for the suggestions.

BTW, I found out that while the 2010 Prius’ battery is fused at 140, the DC to DC converter output is only fused at 125. Looks like the latter (actually fusible link) sits under the fuse box in the engine compartment. If so, it might be a b**** to change. No thanks. To avoid blowing it, I’d want to stay well under the 125…and who knows how much the car draws for its computer, engine fan and whatnot in “Ready” mode? 10 amps…20? Not sure how one could guesstimate that. In any event, there would not appear to be a whole lot more power available for an inverter from the 2010 model over the 2003.

Dcb’s idea of a battery bank would free me from the worry of blowing that darned fuse…at a price, of course. All food for thought. Thanks again, guys.

Mike