In alt.home.repair were some inneresting threads that drifted toward using inverters on running cars in place of generators, for supplying power during outages. Cupla Q's regarding this strategy.
What kind of wear and tear occurs on an alternator when operated for prolonged periods at near its max output? Prolonged = 6 -24 hrs.
Is there a preferred (or easy) way to get wiring from the engine compartment to the cabin? If I drill a hole, do they sell sealing grommets or somesuch?
I'm surprised vehicles don't come with 120 V in the cabin. Mebbe they do now, but still not as a matter of course.
What might be some amp ratings of really high output alternators, and what vehicles would accommodate these?
Some inverters with impressive power at low prices: 1.5 kW for $91, 2.5kW for $147.... wow
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Here's a 5,000 W cobra for $310:
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5,000 W would require an alternator with near-500 amp capacity. Do these exist?
They melt down. They are designed to keep the battery charged, not run the car. They will require their own cooling system.
??? That is an odd question considering the engineering and technical skills necessary to install of the rest of the system.
120-500 amp. You can put one in almost any car.
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Yes, you can get them for roughly one dollar per amp. Figure on at least $1000-$1500 to re-engineer the mounts and wiring. Another few hundred or thousand for the alternator cooling system. Large inverters are hard wired. They don't plug into the lighter outlet. Regardless of amps, the engine will have to run at least 1500-2000 rpm. About 4 gallons of gas per hour.
Depends what you're running, and how. One guy reports he bought a 1000 watt inverter (continuous, 3000w peak) and hooked it to his car. Plugged his fridge in. That drew 1200w start, then 190w running the compressor. So if you just want to save your food, every few hours you'll go start the car, then plug the fridge in. When the compressor stops, you unplug the fridge, let the car run another 5-10 minutes to make sure the battery is charged, then shut it down. Probably don't have to worry about battery charge with those conditions, since a car's accessories (headlights, tail lights, radio, etc) typically take 60 amps with no battery discharge. The fridge took less amps than the low beams. It's all in measuring watt use. The voltage regulator kicks up idle enough to handle typical demand. Not sure where the typical amp number is, but 60-70 is close. With lights and accessories off, the fuel pump and ignition might take about ten amps. That leaves about 600-720 watts available without touching the gas pedal. Then take off 10-20% due to inverter losses (you have to get into the weeds to size your inverter right for best efficiency) and you still have 5-600 watts. All at idle, with a stock 90-100 amp alt. You can do a lot with those watts in a power outage. Run the fridge. Get some light. Run your furnace. Maybe more if you want to dig in.
4 gallons of fuel an hour is way out of the ball park for emergency car inverter use. That's about twice I use moving my car on the highway at 70mph. The alt won't put near that load on the engine, and doesn't have to run continuously. Don't expect to run central air off a car inverter, but you don't need much juice for many other things. It's a good emergency power option if done right. Main thing is heavy leads from the car battery to the inverter. Only reason I didn't buy one is I've only had one long outage in many years. What, me worry?
My experience running VW bug alternators and GM 1-wire alternators on wind generating systems is that they will run continuously with a reasonable load for about three months and then the bearings fail in horrible ways. The bearings are not intended for continuous long-term use. The regulators are also undersized but I never used the original ones.
Yes, you run it through the firewall and seal it up. Usually there are plenty of available holes, but if there isn't one you can make your own.
You name it, you can order one. Usually if you want a lot of power in a vehicle you go to a 24-volt system with one of the big GM alternators. I know a lot of guys with radio gear in the car who have installed a second alternator to power a second system for the radio gear while keeping the existing alternator in place.
That's why a 24V system or even a 48V system is a huge win.
In addition to the other points that have been made, it should be noted that a generator is designed to produce a true sine wave AC output, whereas an automotive inverter is not. Some devices, particularly those with AC motors or transformers, may not operate correctly on the inverter output. Additionally, the high startup current of some AC appliances could overload the inverter.
The solution for this, though, is to avoid the crappy Chinese "modified sine wave" inverters and buy something solid with a real output transformer. Yes, you'll pay a lot more, but it will work the way it's supposed to.
I'm sure that others have pointed out the same thing, but I would think that that would be a really inefficient way to generate AC. Now I'm somewhat of a hypocrite as I do in fact own a small 450W inverter because I like to be independent, but I wouldn't want to rely on it to power a house, or really, anything except in an emergency. Couple of things - first, a typical automotive alternator is rated at somewhere between 100-150A which would translate to 1200 - 1800W, or basically one branch circuit or less. Not enough to do anything really useful, and an inverter rated for those loads ain't cheap. Second, running an alternator at full power for extended period of time is probably not a good idea unless you have an older vehicle with a really robust alternator (in which case it may be in the 35-60A range, making it even less useful.) Third, the inverter is going to be an "approximate sine wave" rather than a true sine wave unless (wait for it) you spend lots of money for it, whereas the waveform of an AC generator is going to be much more sine-like. Fourth, why would I spend the money to feed a
300HP engine to produce 1200W (less than 2 HP!) clearly that's going to be less efficient than using a 5-10HP engine to drive an appropriately sized generator.
Really, a small portable generator is the way to go, no question about it. Inverters are handy, but their place is not to power one's house during a power outage. They can be useful if you need to power a laptop, say, and don't have a 12V to whatever you need power brick, or need to run a power tool or TV far from civilization, but not really much else.
There are plenty of people who use them to keep their food cold during an outage, supply some lighting, etc, etc, and even beyond that. Others buy a generator. I don't want a generator, and prefer an inverter for emergency power. Most of what you said has already been debunked. For emergency home power, you don't use many watts, so you don't burn up your alternator. Sure if you want to live "normally" during an outage, invest in a generator and what's needed to tie it into house power. And hope it starts when you need it. Like anything, you have to do your homework, and set it up right.
Well, it certainly isn't going to run my shop! :) :(
and an
I'm seeing 1500- 5,000W Cobra inverters for $90-310.
Second, running an
The alternator is the bottleneck. But a small battery bank could greatly help in this, as well -- I hope. As you point out, the alternator itself is good for mebbe 1,000 W, continuous. A battery bank could mebbe up this to 5,000 W intermittent -- with the alternator then charging the batts at lower loads..
I do wonder, tho, about the longevity of an alternator at prolonged high loads.
Third, the inverter is going to be an "approximate sine
I'm going to test my bitty 500 W inverter on my pc, see what happens.
Fourth, why would I spend the money to feed a
Not nec'ly. I cited some fuel consumptions elsewhere, where the idle consumption of my 180 hp Frontier pickup is 1/3 that of a full load 13 hp Honder genset. What remains to be seen is the consumption of the Frontier engine at an equivalent load -- but I have an idea it will be comparable or less.
I basically agree, but 1,000 W is better than nothing, and at a cost of about $200, and super quiet, and, as Vic points out, guarownteed to work. Generac-type automatic standby's are nice, but the total bill for those is really high.
This is all risk-reward, a gamble: How much do you pay for something that may not happen at all, or may just occur in semi-ignorable blips? That's the real Q. 1,000 W of cheap quiet power (sine wave or not ) seems to be a good compromise.
And this is after putting some effort into setting up an 8,000W tri-fuel genset, before it grew feet. In a sense, the theft was sort of a favor, bec the setup that remained was pretty onerous.
An inverter also gives nice portable power, altho again, a battery bank proly would really help. We'll see what happens.
It would be great if automakers would make room for a sep. 120 VAC alternator/regulator option -- should be a hit in pickups etc.
Of course :) but if I still lived the one place that I lived where outages were regular and prolonged, I'd be using a small portable generator rather than relying on my car and an inverter I think.
I remember looking at those and they weren't particularly highly rated. When my old bought at the parts store inverter died, I got a "Thor" brand one but it still is not a true sine wave inverter. I think my
450W one was not all that expensive, but a 1000W one is about $100 or so. Inverters of that size really do need to have beefy cables connecting the inverter to the battery so as not to introduce voltage drop.
Yeah, I have my doubts about that as well.
Your PC likely won't care as in reality it runs off of DC internally anyway, so that 120VAC is getting converted right back to DC anyway. I have a universal laptop brick that will feed my laptop nicely off 12VDC, more elegant yet than an inverter. I'm sure there's probably an even more elegant solution intended for those who use PC motherboards for high-end in car entertainment. An electric motor might actually care about the sininess of the wave however.
That bit was an assumption on my part, but I still would think that the frictional losses would be significantly higher in an engine whose displacement is measured in liters as opposed to cc's. But then again, I haven't seen a turbocharged, direct-injected generator set (well, not one that wasn't permanently installed, anyway. I have seen some quite large generators that were both, and Diesel-powered besides...)
I'm sure that some off roaders probably have done a 2nd alternator dedicated for AC use, I'm guessing that it wouldn't be too hard to do a three phase AC thing with an old automotive alternator by removing the diodes, then you'd just have to install a hand throttle and size your pulleys so you could spin it at 3600 RPM whenever you wanted to use it as an AC generator. I'm not that hard core that I've seriously investigated such things though.
I mentioned elsewhere that I was in the process of "properly" setting up a bonafide tri-fuel generator -- gasoline in portable mode, nat gas in prolonged-outage mode -- that was quickly purloined. I was actually rigging the thing electrically to power the shop, as well.
But, holy shit, what an effing pita to set up!!!! For an event that may not happen at all, or may be just a few hours, AND.... if it DOES happen..... the fukn generator might not even start!!!! And noisy beyond belief.... with a Honder engine!
Actually, I had not even begun the real setup, just the testing, and the TESTING was a pita!!! So that's why I'm looking at the car/inverter route.... and now, even THAT is proving to be a bit of pita.... LOL
But hopefully much less of a pita, and hopefully when up and running, will be useful as a portable generator as well, or just for AC in the vehicles. These inverters certainly won't power the shop, but at least there will be something.
The house-heat is an issue as well, unless you have gas-fired circulating HW, which uses minimal electricity. That could be solved by temp. gas connections to ventless gas heaters.... another pita, but workable.
In the alt.home.repair group, where all this originated, one piece of advice for outages (that is sounding better and better) is to simply forget all the "preparedness" bullshit and just "get out of town".... LOL
I've had a system like that for a LOT of years. Mine runs on Gas or Propane.
Not hard to quiet down an engine. Just takes some baffles and a good muffler.
The ones we use on the FD gear (and the one in my POV) all get used and tested quite a bit. You have to connect them up with the proper wiring. No lighter plugs or light crap like that.
I can run my entire place off the gen set as needed.
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