Generator/Inverter question

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bogie

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How large an inverter can one run off a "normal" automobile engine/battery setup?

It's just that I figure that I've got the van with a 30 gallon tank, and a decent muffler, and the car with a 12 gallon tank, and a better muffler, or I can, in the event of an extended power outage, run the "hi, I'm loud, and can be heard a block away" portable generator...
 
I'm assuming you're running the inverter to power the dremel you're using to tweak your newly acquired handgun. (To keep it gun related)


:) The factor will be the amperage output of your alternator. They vary from really crappy models that put out 30-40 amps to the setup on my Excursion that has 2 (yes, 2) 135 amp alternators. (It's an Ambulance setup). I think the 'typical' alternator on a regular car is in the range of 80-95 amps and you'll have no problem running a 1500watt inverter and I think you could probably get a bigger one going. (There's a fairly simple conversion of amps to watts, so convert the output of your alternator to watts and deduct some to allow the engine to run) Batteries don't really enter into the equation UNLESS you intend to just run the inverter off of the batteries until they're dead. (You can put in a battery isolater switch and use the Alternator to "help" the batteries live longer while using the inverter, but don't run down your chassis battery or you'll not get it started again)

(Camping World is great to deal with for Inverter tech)

Just my .02

Regards,
Dave
 
Why not go to your local CSK auto parts store and buy a Champion 4000 watt generator for $399 and use it? They are quiet and powerful and known as the best buy for the money by the RV croud. I have one and it is great.
 
The primary question, as always, is "What do you need to power, and how much power will you need to run it vs. the larger amount of power it takes to START it." Always size your generating capacity for how much power load it takes to START something electric, versus how much it takes to KEEP it running.

There are other places out there on the web much more suitable for this sort of discussion than S&T, with the variety of home power/alternative power sites, RVing sites, etc. It is certainly wise to look for alternatives in advance of need, and prepare ahead of time when you have the luxury of time to manage the learning curve. Take a look at http://www.timebomb2000.com/vb/showthread.php?t=167378 , which is the first report from an acquaintance in south Mississippi who had prepared in advance for a hurricane like the one which eventually became known as Katrina. If you look around that site, you might still be able to find more of the threads where he talks about building his 'bugout bus' beyond the one at http://www.timebomb2000.com/vb/showthread.php?t=147798 . Since he put his work to the test, and it did what it was supposed to, that's the sort of thing I'd pay attention to were I you.

lpl
 
I'm with crank, why not get a quiet generator? It WILL use far less gas and provides a good ground hook up to save electrical shocks. It also means you can take the car out of your garage to go somewhere without having to turn off all of your electrical items.

I mean after all, if you are doing a dremmel number on your 1911, do you want to have to start all over again? :eek: :D
 
bogie,

Why?

BTW, if you have a generator and you don't like how loud it is, just replace the muffler with something better.
 
I think the 'typical' alternator on a regular car is in the range of 80-95 amps and you'll have no problem running a 1500watt inverter
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80 amps at 12V is less than 1000 watts. And keep in mind your car needs some of that juice to keep running.

Its a poor idea for many reasons including fuel economy, but also that it keeps you from using your vehicle for its intended purpose.
 
Well, I haven't seen a -quiet- generator that puts out decent amperage for under a grand... Was also thinking that a vehicle is by definition mobile, so in the event one has to go somewhere, one has the power source without carting along a bulky generator... Down where I'm in the process of schlepping all this crap to, a running generator may as well have a "steal me" sign on it... At least with a vehicle, I can set it up to where it ain't gonna go anywhere unless I want it to...
 
Well, I haven't seen a -quiet- generator that puts out decent amperage for under a grand... Was also thinking that a vehicle is by definition mobile, so in the event one has to go somewhere, one has the power source without carting along a bulky generator... Down where I'm in the process of schlepping all this crap to, a running generator may as well have a "steal me" sign on it... At least with a vehicle, I can set it up to where it ain't gonna go anywhere unless I want it to...
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Keep in mind that most inverters of this sort are not really designed to be permanently mounted in your vehicle so you would need to do some rigging to make it convenient to use. There are a few cars that actually come with built in inverters. Don't know how much juice they can give you. You can also buy generators that mount under the hood and are connected to the engine via a drive belt. Mostly this is an option for trucks.

A running car is not all that hard to steal either.

If you decide to go this route, get a higher capacity alternator. Car alternators are not really designed to provide the rated current for any long period of time.

There is also the issue of idling your car for hours on end. That is not real good for it.
 
My suggestion, get a 4 cylinder deisel generator/welder, they just sit there and purr like a kitten trust me, but if you're not a welder I don't know what to tell you 'cause if it were me it'd get more welding use then power generating, also with the deisel you can have it converted to full solely off of propane which cost about have the price of deisel here
 
http://www.cpeauto.com/C46540.php

I bought one of these at Murray Auto for $399 ($299 after $100 rebate). It is quiet, powerful and as good a deal as you will ever find on a generator. Yes I know what I'm talking about as I have been a RV'er for 30 years and have seen everything out there over the years as far as generators go.
 
In the event of a "bad weather" situation, I'd rather my house not become a magnet for someone looking for something desirable to steal...

May just try to build something piping one of the lawnmower engine dealies into a larger underground muffler thing...
 
Go propane. Camp stove, lights, etc. We used them during the last ice storm when power was out for three days. We ice bagged the freezer and frig to hold them over, and grilled what we had frozen to use it - that's why it was there.

And the vehicles were available to fetch more propane and go to work. Some places still had power - like my job less than 150 yards from a substation.

We heard a lot of complaints about the cost of running a generator daily - at $3 a gallon, two fillups a day, about $30 daily just to keep a freezer or frig going, plus TV, etc. That's $200 a week on a major outage, if you can find the gas station with power to pump it.

And that one may need security in the form of a highly modded .45 toting cashier.
 
We heard a lot of complaints about the cost of running a generator daily - at $3 a gallon, two fillups a day, about $30 daily just to keep a freezer or frig going, plus TV, etc. That's $200 a week on a major outage
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you could run them for 10-15 minutes an hour just to keep the freezer stuff frozen and the fridge cold.
 
For contineous use you would be using a lot of gas for a little power. To acheive any decent power output the inverter would have to be wired directly to battery and ground and the engine run at a fairly high speed so as not to discharge the battery. I have a 300W inverter in my truck, plugged into a cigarette lighter outlet and use it to power a laptop and a 10" high velocity fan mounted in window pass through between truck cab and camper body, to put heat and ac in back for the dogs( It's too hot in a Texas summer to put them in back without some cooling on long trips). This inverter is about 3.5-4" hx 10"wx 15'L and has it's own built in cooling fan. I can only imagine the size and weight of a larger output model, probably would take a lot of space.

My portable generator, and thats a laugh, a 11Kw continous output 20 hp Honda, weighs just over 400 lbs and burns 1.7 gal /hr and will power my all electric house with the hot water tank turned off. This does include a 4 ton heat pump, refrigerator and two freezers. We can use use any lights, microwave, stovetop, and I once had to start my 220v 3hp table saw, but that was an extreme starting load, everything slowed down/dimmed but it carried it. I will never do that again unless I make sure the wife is not cooking as she was that time, and will turn most other things off.

Even with the high cost of gas I had 50 gal on hand for Ike, and only used 5. You do not have to run a generator 24 hours as day. We usually ran just before going to bed, and after getting up, to cool house down, for cooking, and a few times through the day to keep refrigerator and freezers cold, and kept things comfortable. I did hear some folks running small units constantly just to power a refrigerator and freeze

Bottom line, get a generator if you need emergency power, get one large enough to carry starting loads of everything you might need to have running at once, and consider setting your house up as I did. I installed a double throw switch and installed a 50amp inlet plug for the generator. The switch is between the meter and circuit breaker box. One motion switches off from utility power to off then to turn on the generator inlet, so there is no possibility of feed back to utility lines and harming some utility worker in the area.
 
Your van is not designed to run at idle for long periods. Even police cars have large cooling systems to allow them to idle.
We use at work Honda 3000is generators, we run them 15 hrs a day sometimes and have few problems. They are quiet. Start with a key. Can't beat them.
 
We heard a lot of complaints about the cost of running a generator daily - at $3 a gallon, two fillups a day, about $30 daily just to keep a freezer or frig going, plus TV, etc. That's $200 a week on a major outage
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We use it more to power the well and a portable AC unit, during Charlie when we didn't have one the worst thing was trying to get some sleep in the 80 degree, high humidity Florida weather
 
Bogey,
I have never done it or witnessed it, but have read you can run the exhaust through the ground for a length & that will help reduce noise. You would still need an addequate muffler. Sounds like a hassle & not portable plus other obvious problems.
In general an air cooled engine is not as quiet as a watercooled engine.

As some have stated getting the quieter generator in the first place would be a good start.
My fridge can go six hours with out power & be fine. (Ambient Temp Dependent??) One tactic on generator is you don't run it all the time.

Quiet is nice for comfort.
 
We just spent a few days without power after Ike rolled through our area. Our water was heated with natural gas, our food was cooked with propane, and our home was lighted with flashlights and candles. Our biggest problem was lack of refrigeration. I'm looking into a propane or natural gas refrigerator right now...
 
There comes a limit in inverters as to how you power them. The cigar lighter receptacle for the most part is limited to 15 amps at 12 volts, or 300 watts. Anything more than that you will have to connect your inverter to the battery.

The next consideration is what gauge wire to use to attach your inverter to the battery. A 15 amp draw requires 14 gauge wire. A 20 amp draw requires 12 gauge. A 30 amp draw requires 10 gauge. A 40 amp draw requires 8 gauge. A 50 amp draw, 600 watts, requires 6 gauge.

I just installed a 3,000 watt inverter-converter in my 34' fifth wheel trailer RV. The cables attaching the inverter-converter to my coach batteries is 4/0 gauge. That's about 1/2" thick copper welding cable. 3,000 watts at 12 volts DC is 250 amps.

You probably won't want to run the automobile engine all the time. To do that, you will need some decent battery storage and figure your load. Deep storage batteries are rated in ampere hours at the 20 hour discharge rate. A 250 ampere hour battery will last 20 hours if you only pull 12.5 amps. That means you are limited to a 150 watt inverter output.

These figures aren't exact, as inverters have a certain amount of loss. To get 150 watts out of an inverter you need to put something like 165 watts into it assuming a 90% efficiency. Some inverters are better than that.

If you only want 150 watts of power, don't overkill and get a 1,500 watt inverter. It is best to match the inverter to the load.

It will be a good idea to isolate the storage batteries from your automobile starting battery so you don't discharge the starting battery to the point it won't start the engine. You can do this with a knife switch or a battery isolator.

Another consideration is how long will it take your automobile alternator to recharge your batteries the inverter is drawing off of. A 100 ampere alternator does not put out 100 amps at idle rpm.

You will also need some means to determine when your storage battery is fully charged. An accurate but messy method is to use a hydrometer to check the specific gravity of the electrolyte.

Pilgrim
 
I haven't used the generator yet to power the house during outtages. Just to keep the refrigerators/freezers cycling a few times each day. And I always have the neighbors standing there with plugs from their extension cords in their hands.:D
 
Generators can be had with sound attinuated enclosures, about 50-60 dB at 50 feet. Pretty quiet.

You can build a brick wall around one and the bulk of the noise is directed upward.

Propane or natural gas would be the way to go. Look into the btu's delivered and compare all the fuels in cost. Figure in a transfer switch, either manual or automatic.

The most economical setup is to size the set to carry the circuits absolutely necessary. Well pump, fridge/freezer, couple of light and recepticle circuits.

You could look into the used market for a genset. They can be had pretty reasonable. The only drawback is if it's pushing 10 years old, you may be looking at control or board failures that may cost you 400 to 1000 bucks within 3-7 years. MOST mfr's still carry parts for stuff as old as 15-20 years old. If you are handy, a lot of repairs can be done by yourself, if not, the shop rates can kill ya. Our rate is 125.00 an hour, plus mileage. If you buy new it should come with a warranty, which is a plus.

Cummins had some 6.5 KW sets on sale either last year or early this summer, seems like 500 to 600 bucks. I considered buying one myself, and I work for a competitor.

Water cooled would cost more than air cooled, but water cooled is the best way to go.

I run power invertors in my service truck, they are handy, but only for the short term. They deteriorate as well, figure on 4-6 years and the capacity diminishes, especially if you have a lot of starting loads on them.
 
Bogie,

If you want quiet (and expensive, and possibly pretentious) you may wish to look at http://www.solarstik.com/ - it is a pair of solar panels on a stand, with a battery pack and inverter, and provision to add a little windmill to the top.

I have no experience with this but it seems like it would meet your "quiet" requirement, and maybe my post will elict a response from someone who actually knows something about this device. I'm real curious.

Regards,
Andrew
 
Personally I think this is a good topic. I need light for my home defense system. I have a 1200/3200 inverter that I rely upon that I can connect to my car battery (I also use this connection when I go out hunting).

I read folks talking about the inverter size. It is my understanding that the inverter size is secondary. What is important is the load placed on the inverter. If I only place 700 watts on the inverter, the 90 amp alternator is not over taxed because only 58 amps is being drawn. The car will not be overloaded, and this inverter will work fine with 700 watts.

Am I incorrect in this ?
 
BobCat the problem I find with solar is my three solar panels are 3' X 3' mounted on a easel that has about a 2' depth. The unit weighs about 50 lbs. All this and I get a mere 45 watts. This works of for very limited battery pack lighting, but for more power I find something else to be needed.
 
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