Powered my house from an inverter

Power out? How about an inverter connected to your car?
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kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Powered my house from an inverter

Post by kevm14 »

And that inverter was connected to my car. Yup.

Back during Blizzard Nemo (2013), we lost power for 48 hours. Which wasn't too bad, but it was cold as hell.

What's fun about this setup is I was toying with the idea for years (and most seriously in the October 2012 time frame) and before the blizzard hit, I decided to run out, just a day before, and get myself a cheap inverter. I had done some math indicating how much power my Caprice could provide at idle. In short, even the police-spec 140A alternator can't keep up with a measly 1500W inverter at idle. The stock CS-144 alternator, with my drive pulley ratios, puts out a max of about 120A @ 900 engine rpm. With inverter losses, and estimating other loads on the alternator, I was looking at about 1300W max continuous power (unverified - my kill-a-watt was pissed at the inverter). I could have done a little better if I used giant DC cables and had a mechanical fan (maybe as many as 100-150W additional). Actually, I calculated the cable loss around 82W at full load and the single cooling fan I had running supposedly draws about 100W. Maybe before winter hits I'll go grab my old fan from my parents' house, and even make upgraded DC cables. By the way, I would have to double engine RPM just to get another 20A out of the alternator (to the 140A max). Not very efficient and that's only an extra 270W!!

The day before the blizzard, I basically made the plan to do this. And the day of the blizzard, I was wiring it up for the very first time. I finished with about 30 minutes to spare, then the lights went out. And it worked very nicely, considering the circumstances.

Pictures: http://www.kevinallenmoore.com/photo/ma ... mId=125162

Video: https://www.youtube.com/watch?v=PtwJyISOU9g
A quick walk-through of my backup generator solution. The inverter is a 1500W unit from Harbor Freight @ $130. For cables, I started with 20' of Walmart Everstart Maxx 4ga jumper cables, cut off a 10' section and crimped/soldered lugs for the battery and inverter (good move, because my original plan was to just clamp some jumper cables on there, which would have been a disaster).

Summary on efficacy:
- Inverter modified sine-wave is lousy and many things don't sound good
- I enjoy the level of integration provided by back-feeding through the dryer outlet (30A-rated circuit and my max is something south of 15A) - MAIN BREAKER OFF. This allows any non-240V load to run (or try...)
- We are able to run most things, serially, such as Keurig coffee maker, microwave, furnace, hairdryer on low, TV/HTPC. All parallel combinations are based on my own judgment. I may try the washing machine. Would love a real-time display indoors with DC volts, AC volts and output load/%.
- The limiting factor seems to be my Caprice's alternator (during peak heavy loads, it may start an alarm and my DVM indicates less than 11V on DC in, but it has never shut down on me - car or inverter)
- Caprice seems to use something under 1 gallon/hour but not sure on the exact numbers
- The vitals on my Caprice seem to remain normal after back to back hours of operation but I expected this. My "generator" has 279k miles!
- I already forgot the inverter was connected to the car and backed all the way into the street with it plugged in. Don't worry, I saved it. But I probably didn't deserve to.
Fast_Ed
Posts: 550
Joined: Wed Oct 23, 2013 9:45 pm

Re: Powered my house from an inverter

Post by Fast_Ed »

Only mod I would make would be a 'tag out' on the shift lever of the car to prevent driving off with inverter attached.

I don't have a way to get a line to a dryer outlet for this setup.. I want to power only my furnace and there is a single outlet attached to it.. I would turn the main and furnace breakers off. Do you think that's possible? I cant think of a reason it wouldn't..
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Powered my house from an inverter

Post by kevm14 »

The tag out is a good idea. For this blizzard I simply setup the Ranger as my vehicle to use if I needed to drive somewhere. With the extra gas can capacity, I would have had no reason to drive the Caprice around. It would only take 2 trips to full the tank from empty.

Your idea should work. The only possible issue you would run into is just the load itself. Startup current issues or perhaps power factor issues (because of the modified sine wave) which would lead to inefficient motor operation.
kevm14
Posts: 15200
Joined: Wed Oct 23, 2013 10:28 pm

Re: Powered my house from an inverter

Post by kevm14 »

kevm14 wrote:I could have done a little better if I used giant DC cables and had a mechanical fan (maybe as many as 100-150W additional). Actually, I calculated the cable loss around 82W at full load and the single cooling fan I had running supposedly draws about 100W. Maybe before winter hits I'll go grab my old fan from my parents' house, and even make upgraded DC cables.
- The vitals on my Caprice seem to remain normal after back to back hours of operation but I expected this. My "generator" has 279k miles!
At least I finally built the second 10 feet of jumper cable and doubled up on the cables, halving the voltage drop. I also had the mechanical cooling fan bolted on and was ready with my improvements. Alas, it was not to be.

For my next house, I will unfortunately need a generator. 240V well pump (excludes most inverters right there), a big forced air furnace (large fan and oil burner pump), plus a separate oil fired hot water heater (another oil burner pump).

Also, my "generator" has another 10k. No particular relevance except that idling all those hours during Nemo did not, in any observable way, harm the car.
Adam
Posts: 2240
Joined: Wed Oct 23, 2013 9:50 pm

Re: Powered my house from an inverter

Post by Adam »

kevm14 wrote:Also, my "generator" has another 10k. No particular relevance except that idling all those hours during Nemo did not, in any observable way, harm the car.
If only you had that "engine hours" display from that Silverado.
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