Use the car as a temporary generator during black out ?

Page 1 of 3  
Is there such a device that you can plug into your car and is capable of turning the car's DC 12V power into household 110V AC ? Please don't laugh if this is a stupid idea, I am just wondering if the power generated by the small alternator on a running car would be enough to drive a force air furnance during black out ?
My neighbour is buying an expensive Honda generator as a backup power supply. Since I can't afford to do the same and black out is not uncommon in my area, I am thinking if the alternator on my three cars can do the same trick and power at least the furnance during a winter black out ?
Appreciate if you can share your knowledge / experience.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com (JW) wrote:

Lessee...a blower motor on a furnace typically runs about 10A @ 120V...that's 1200W continuous. I'll ignore the startup current, but it's probably pretty gnarly. 1200W inverters are out there (primarily for the RV crowd), but they ain't cheap. We're talking 100A+ out of the battery, which is quite a draw -- you're not going to get that out of the alternator -- basically you're going to suck the life out the (non deep cycle) battery in short order. Now, RVers address this with a bank of deep cycle batteries, but you're getting into the range of a genset by the time you've bought the batteries and the inverter (it's quieter, 'tho).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andy Hill wrote:

My furnace has a 8.5A fuse in a fusable disconnect (I don't know why, I didn't wire it like that) and it doesn't blow during startup...
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
andy snipped-for-privacy@hp.com (Andy Hill) wrote in

You'll want to check that again.
--
Bert Hyman | St. Paul, MN | snipped-for-privacy@visi.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload


Indeed.
Most of the forced air furnaces I've seen use 1/4 or 1/3HP blower motors, occasionally 1/2HP.
Even a very poorly efficient 1/2HP shouldn't be more than about 7 or perhaps 8A. A gas generator should be at least double that to drive the blower, and an inverter, probably triple.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sometimes when one pulls numbers out of one's *ss, they stink a bit. OK, overstating the case a for a residential furnace. Still strikes me as a marginal idea, at best.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
andy snipped-for-privacy@hp.com (Andy Hill) wrote in

For a ->true emergency, it might be OK. But, an inverter with enough oomph to handle the motor starting loads would still be a big purchase. If you're serious about this, spend the bucks and get a real generator and a real transfer switch.
All this has a certain immediate interest to me since I was awakened at 4AM today by the shriek of my CO detector as it died from a power outage. Power's back on now (I called home and the answering machine picked up), but next time, who knows?
--
Bert Hyman | St. Paul, MN | snipped-for-privacy@visi.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Actually, maybe you overstated for newer blowers. However, some of the older ones can be that high. My old furnace, replaced about 15 year ago and built in 1970, ran pretty close to 10 amps.
Andy Hill wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'd guess that the full-load or startup amperage on the motor could be that high, but I doubt many furnace blowers would take that much current once they were running..
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from snipped-for-privacy@nospamshaw.ca
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The usual plate ratings on motors are "worst case full load" (delivering full rated power under worst case manufacturing tolerance and supply voltage).
An efficiently matched motor and blower will be pulling "full load" (not necessarily "worst case", but close) amps all the time. This goes for pumps and compressors too.
Startup surge is 2-3 times that (and not listed on the plate).
In other words, a 10A blower motor _will_ pull close to 10A continuously. 20-30A startup surge.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
| An efficiently matched motor and blower will be pulling "full load" | (not necessarily "worst case", but close) amps all the time. This goes | for pumps and compressors too. | | Startup surge is 2-3 times that (and not listed on the plate). | | In other words, a 10A blower motor _will_ pull close to 10A continuously. | 20-30A startup surge. | -- | Chris Lewis, Una confibula non set est | It's not just anyone who gets a Starship Cruiser class named after them.
That's interesting. My oil-burner furnace is on a 15 amp circuit breaker. The largest draw seems to be greatest when the oil pump fires up, not when the blower starts up. I don't think the typical furnace blower motors are even close to 10A running.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
remove the urine to answer
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
JW wrote:

You can buy little inverters that run off your car battery and generate 110V AC. I bought a 400W inverter for about $50 (then found the same one at Sam's Club a few months later for $25. D'oh!) The size you need depends on the power requirement of your furnace blower. The inverter does not need the car to be running; just the battery charged. You'll have to run the engine every once in a while to top off the battery. You might want to buy a deep-cycle battery just for this use.
How are you planning to wire it up?
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
There are inverters to run off your battery but a 50 amp alternator of 12 v will give apx 420 watts at 120v. Furnaces require probably 700 - 1200 for surge startup , 350 - 600 running for a small relativly new furnace. So hooking it to the battery would work , if the inverter is putting out 60hz. But you would be running the alternator at full load, they dont last long that way, and you need a good inverter, 60 hz stable. I dont think an alternator would last long though, but you could try. A new alternator + inverter is 300. A fairly good cheap gen 500.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are 12V inverters that you can buy quite cheaply to get 120V AC power[+]. However, above about 400W the price starts to jump _very_ steeply. Given startup surge and wave conditioning requirements for AC induction motors, an inverter for your furnace blower will have to be in the 2000W+ range. Those things cost more than a consumer grade (ie: Coleman) 3500W gasoline generator (but not as much as a good Honda).
Furthermore, at that power level, the vehicle's alternator may not be able to keep up. 60A is about the limit for ordinary cars, 75A is the usual "top end". Which is only about 720W. The furnace blower steady-state is going to use up just about all of it.
There are "special" alternators you can install on your car that produce 120V AC - making your whole car a gas generator. They're actually quite inexpensive (years back Northern Hydraulics had them for around $60), _except_ that mounting them is often going to be a b**ch.
These are able to deliver several thousand watts, _however_, they're not frequency regulated, and thus would not work for furnace blowers which need a reasonably well controlled 60Hz AC. They're more intended for things like electric drills and saws that don't care what frequency the 120V is at.
Sorry, your cheapest option is a gas generator.
[+] I have a couple smallish inverters, and will be building a 12V emergency lighting/power system in the house. But I won't be able to run motors like that, it is not intended to be as "capable" as a gas generator. Just simple, cheap, keeps the lights burning, we can watch emergency broadcasts on TV, and recharge the cell phone ;-)
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
My father-in-law used to buy these devices for his employees fleet cars. They worked in the oil patch, and needed to use drills, etc.
He and I opened one of them one day to see what he was getting for him money. It was essentially a switch and a 110 receptacle.
The switch cut the voltage regulator out of the circuit and ran the alternator on full output. The frequency was whatever you get out of a three phase circuit running at frequency x.
Sure they worked. I don't recall him ever having burned out alternators because of it either. But it darn sure wasnt rocket science. And you are still limited to the wattage that the alternator can put out.
Last point, if one thinks an alternator doesn't put out much at low RPM, he should remember the days of the generator. These things were borderline at best, always seemed to have voltage regulator problems.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

As a FYI, some years ago there was a discussion (on this group I think), where I had suggested that an "alternator configured as 120V source" unit was limited to about the same wattage as when configured for 12V (ie: somewhere in the 500-800W range typically).
An automotive engineer familiar with alternator design chimed in and said that, on the contrary, these things can put out vastly more power. As in, a 60A alternator reconfigured to drive 120V could actually deliver 60A at 120V (7200W at 120V instead of 720W at 12V) under the "right conditions".
That would presuppose you're running it at high RPMs [+], and secondly that current draw and voltage were exactly in sync (ie: pure resistive loading). If there was significant out-of-phase current/voltage at those power levels, the thing would self-destruct in very short order because the thing isn't big enough to dissipate the inductive heating.
It also supposes that the drive belt can stand up to 10 times as much loading...
[+] the amount of power that a given size of transformer or generator can generate is highly dependent on AC frequency. Ie: a PC switching power supply can supply 500W out of a transformer 1.5" in diameter, (because the transformer is being driven at anywhere from 20Khz to 50Khz), whereas an ordinary 60Hz transformer for that wattage often weighs 5 pounds or more and is bigger than an entire PC supply.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Backtrack and think about what you are trying to do. First the Honda generator costs about four times any others. If you need a generator for high usage all the time the Honda is the way to go. You can buy a 5-6 kw generator for around $500. It will do everything you need and probably last you a lifetime at the small usage you need. I bought a 6kw generator about 8 years ago for about $400 and have used it about a dozen times. I have it set up so it feeds the whole house during power failures. I had lights, TV, and hot food during the blackout. It won't run the air conditioner but it did run several fans. Check the prices at the big box stores and warehouse stores. You don't need state of the art for the small usage it will receive....

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
There is a company called Auragen that makes this type of thing. They are at http://www.thepcshopper.com/aurasystems /. While the units are really nice, they are pretty pricey. I am currently looking a putting one in a mobile TV truck, about $3K. As others have said, a cheap gas generator goes a long way in an emergency.
JW wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com says...

As it is now alternators on cars are becoming more and more taxed at providing enough power for all the widgets and things on a car.
This is part of the move to the 42V electrical systems in cars. I can understand that - takes 48V to run your phone why not something like a car.

Best way to use your car as a generator is not to. You could buy a basic generator and then wire up your house to accept it as an input. You'd probably be looking at about $3000 or so.
Other option is a truck with a PTO hooked to a generator. But even that isn't cost efficient.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.