Inverter vs generator

I am an apartment dweller and I doubt i could store a generator, gas if not get gas when it would be needed. Then of course if I did, I would have to put the generator outside and it may be stolen as the back is open, no fence.

Early on, living on my own attend community college I wished we had a student microwave. I figured it wouldnt be too difficult if i could drive to get an inverter and microwave to put in the trunk of the car or van or what ever it was I may drive. I never gave it much thought after that.

Well, as of May of this year I started work for a company that sells bucket trucks, platform lifts and truck cranes. All the trucks have an inverter on board. 1500 watts min 3000 watts max. THe 1500 watt ones have a third battery where the 3000 has a second alternator and 2 extra batteries. They claim it can be used for everything at a job site and the main thing is to start the truck before you use it and leave it running to keep it charged.

It occured to me, that may not be a bad idea for me. Get an extra battery or two, higher output alternator or a second one and isolator and a big honking inverter so I could have emergency power like that. I imagine a car or van could run for days on a tank of gas at idle and I could use the power for my fridge, cooking and tv. The parking out is right outside my window so it would not be much of an issue to run an extension cord from the van inside to where i live.

What do you guys think?

The only real negative to that I can think of, is the wear on your car. Prolonged idling, especially for automatics that tend to idle higher and higher, is bad for engines. Diesel engines can take it more than gas, but it's still bad for them. They weren't made to idle at the lower speeds for long periods.

cobb,

You might find this ineresting ...... The Epicenter.

Check out the entire site, has lots of stuff.

You may find that the cost of adding the battery, inverter and extra alternator will be a lot higher than the cost of a small generator. The installation of the alternator requires that custom brackets are made and installed, then you need non-statndard belts to fit it.

The Honda inverter series generators are very fuel efficient, though expensive. The smaller ones are small enough to fit under a kitchen chair.

I may end up with a van, which may have a bracket for a second alternator or accessory under the hood. Of course I may add a larger alternator to it if it does not come with it and of course a larger battery. The inverter would be mainly used for quick stuff, like to microwave food or to charge my wheelchair whenthe power fails. My power does not fail all that often. Its more of an in emergency thing than a regular service item.

I will check that site out. I have free gas and a gas stove, wonder if i can take advantage of that for free power or emergency power? Ive used it to cook and heat when the power fails.

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Unicorn said:
The only real negative to that I can think of, is the wear on your car. Prolonged idling, especially for automatics that tend to idle higher and higher, is bad for engines. Diesel engines can take it more than gas, but it's still bad for them. They weren't made to idle at the lower speeds for long periods.

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If it's a fuel injected vehicle, there is absolutely nothing wrong with idling indefinately. Most will drop to around 600 RPMs once they've warmed up. Think how many hours police and construction vehicles idle with the AC on full blast. You just need to remember to change your oil more often, since you're not counting miles but still putting hours on the engine. I've got a 300 amp alternator, dual batteries, and a 2500 watt inverter installed in my Tahoe. Great for camping! /ubbthreads/images/graemlins/grin.gif

...

I idle My vehicals alot and have never had a problem with that, they are all fuel injected.

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Another issue is at 600 rpm's the altenator is only putting out a fraction of rated amps. if load exceeds output, may knock out the altenator. if you have a 300 amp alt, output is still aprox. 60amps at idle. plenty for just about anything

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60 amps at 12 volts is only 6 amps at 120 volts (not counting losses). My coffee maker draws more than 12 amps. My 1000 watt micro wave draws a significant amount, as much as 12 amps, though I'd have to check.

Daniel

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cy said:
it may not hurt the motor to idle for extended periods, but will have a tendency to foul the motor.

Another issue is at 600 rpm's the altenator is only putting out a fraction of rated amps. if load exceeds output, may knock out the altenator. if you have a 300 amp alt, output is still aprox. 60amps at idle. plenty for just about anything.


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No, it won't. Carbureted vehicles do have problems idling for long periods, but fuel injected vehicles do not. It is absolutely no different than driving your car, just slower.

As for the alternator, mine is designed to put out 200 amps at idle. Many aftermarket high output alternators are actually lower output at idle, but stock alternators are usually pretty good - with around 75% of their rated power at idle. If you were to install a second alternator, you could probably use a different pulley ratio for it, and make it spin faster at idle than a normal alternator. This would of course shorten the life of the alternator...

,,,,,

I have always understood the same. Modern multiport fuel injection engines can adjust the mixture at idle so well that it doesn't hurt the engine any more than driving at a normal speed. Many vehicles spend more time idleing that driving in big cities and the engines do fine.
I have a battery isolator and a second battery in my truck. I'm using an old battery I had but intend to get a deep cycle someday. If you get the deep cycle you don't have to leave the truck idleing all day long, you can charge the battery while driving to the location, run the battery down then start the truck to charge it back up.
Unless you do change the pulley you won't get full charge from the alternator.
I've always thought it would be interesting to put a pair of overrunning clutches on the front shaft of an alternator so it can be driven by either of two belts, one belt is on the truck engine and another is a small 5-10hp engine. Park the truck and pull the rope to start the small engine and it runs the alternator. Move the overrunning clutches to the crankshaft of the trucks engine and the small engine will run the whole accessory belt giving alternator power and A/C /ubbthreads/images/graemlins/smile.gif Probably not any ore efficient than a modern engine though.

Police cars have larger radiators to help prevent heat build up when left at idle. Electric fans have made a big difference in the ability to idle for long times without overheating.

There have been cases where cars caught fire after extended idling. One of the small fords was recalled due to a fuel system part that overheated without the airflow associated with driving.

Back in the 60's it wasn't a problem. My dad's Chevy wagon would vapor lock before we hit fire danger /ubbthreads/images/graemlins/smile.gif

Daniel

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cy said:
This in news to me, auto engines are designed to be ran at normal speeds and idled a relative small part of the time.

typically what I've seen is 20% at idle.

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It doesn't matter what engines are DESIGNED to do, it's no different for the engine if it idles for 5 minutes or 5 hours. In any computer controlled vehicle the mixture will be the same at idle as normal highway speeds. That's why fuel injected vehicles have eleventy billion expensive sensors all over the place.

And no, 20% at idle is definately not typical. A car is designed to be able to run the engine, headlights, stereo, heater or AC, electric cooling fans, and defroster at idle. With 20% of the output from the alternator, the voltage would drop well below the normal 13.5-14.5v very quickly. That doesn't happen in any car that is running correctly. My old jeep only had an 80 amp alternator. 20% would barely run the headlights. Most cars only have 60-120 amp alternators.

apologies for getting into a p*ss*ng contest. posts deleted.

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cy said:
aplologies for getting to the point. but where you are getting your info from? Mine is from many years of working with cars. Do you even know how to work on fuel injection?

How many altenator have you tested? How many dead altenators have you handled?


FYI a car will run just fine, with all the lights, horn, etc working with a DEAD altenator for a very short time. until the batt runs down.

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I build high performance and often fuel injected marine V8s for a living. I have put together several fuel injection systems together FROM SCRATCH. Have you? I also have allways had an interest in generators, I have personally made 5 different automotive alternator based generators/welders. I have rebuilt several alternators. I've even converted one to use permanent magnets and generate alot of electricity at 400 RPMs. I know my s**t.

That said, anybody should be able to see that 20% of an alternators output is not enough to keep a car running, and thus, manufacturers would not make vehicles that do that. The VAST majority of vehicles have 60-120 amp alternators, that's 12-24 amps at 20%. That's not enough to keep all of a car's accessories running - that's not enough to keep just the heater running! Whether a car CAN run without an alternator all together is irrelivant. If what you are saying was true you could turn on your headlights and heater and leave your car idling and eventually it would die when it ran down the battery. That doesn't happen. Whether or not it's good for the engine, you CAN leave any vehicle idling indefinately and it will have plenty of electricity to do so with all of it's electronic accessories running.

BTW - this guy is just talking about using a power inverter for a few hours when the power goes out. It's not like he plans on leaving his car idling 24/7 for weeks on end.

Hi guys, let's all take a step back and breath a little bit. Everyone has the right to express an opinion. Of course MINE is always the right one. /ubbthreads/images/graemlins/wink.gif

Let's not let this conversation get ugly.

ok? everybody? /ubbthreads/images/graemlins/happy14.gif

wow I did not know that my alternator would only put out 20%
at idle and that my car had 11enty billion sensors.
Both thoughts are bull.
I work on a lot of cars. some cars have kinda marginal cooling systems for idling for hours and hours on a hot day.
as far as I know modern fuel injected cars continue to run closed loop even when idling so as long as the cooling system has no problem-idle away.
If you do not know what closed loop operation on a modern engine is you do not know enough about modern engine
management systems to have a valid opinion here-in my opinion.
I have read about car engines converted to run on natural gas used on houses in the boonies to provide heat hot water and electricty-I bet that they are not running them at 5000 rpm.

20% at idle? I know or a fact a gmc 3500 truck gas powered at our shop was putting out 35 amps at idle with lights and ac on Wednesday this week. Most of those trucks have higher output alternators on them and in case of a 3000 watt inverter, two.

Before they used a pto or a accessory pump hooked up to the engine, they used an oren generator with a pump hooked to it as well. They used that generator to run the hydrolics and power.

The inverter deal seems to work for them and is standard on their trucks. THey have a range of trucks, gmc, chevy, ford, isuzu and internationa. Gas and diesels, 4 cylinders, 8, 10 cylinder engines. They also use 12 volt compressors for those who needs air, but welders are gas powered or stand alone. Same with pressure washers. Some trucks they tap into the system if it has air brakes to give them air.

I know of many disabled people who use a small inverter plugged into the cig plug to rechage their wheelchair while on the go, or during a power failure or to charge other batteries if they use a vent or to even run a vent. I just wanted to take their idea a step futher and do what they do in the shop where i work and make it a large unit, with an extra battery or two, maybe a second if not a larger alternator and of course, extra cooling, electric fans, upgraded lighting and other stuff to the van. I wouldnt leave it stock. I would also add a trans cooler or an extra one.

What did I miss? I did not want to turn this in to any contest. I think we have a bunch of guys here way smarter with more experience than me and wanted some opinions after reading Dieselsdaves experience and his recomendation on generators.

You are right, engines are designed to run at a range of speed and running at a fixed speed it will shorten the life, something to do with the rings if I remember right, but this is not convertng a van to a stationary generator. I just want to beef it up to use for a few hours to run my fridge. I am sure it would not be a problem with the stock system to run a microwave for 30 seconds to heat my lunch.

Honestly I wouldn't mess with changing the stock alternator unless you're planning on using it a lot. I had a stock 80-amp alternator and the main battery and two 120a deep cycle batteries in the trunk with a 2400w inverter. Unless your running things constantly the regular alternator should be enough to keep them topped off. Remember even if a microwave pulls 10 amps at 120 or 1000 amps at 12v it's not on for long and when it is off the alternator should catch back up. So unless your running 300+ watts all the time you should be ok.

My old car, a 92 Mazda 626 put out about 20 amps at idle and about 40 at 2k. I tested this charging my house battery bank for my inverters, 8 Trojan T105's running stacked 5kw of inverters. On our new car, a VW TDI diesel it puts out about 35 amps at idle and about 45 at 2k. I did this via a #4 run from the garage to the battery bank. Remember these are just to my house batteries, not including any power going to the car battery. Also the house bank was running right about 12.6v at the time with a light load, about 80 amps, I am sure the alternator would put out more if I had the batteries under a larger load or if I wasn't running through 50 feet of #4.

Bottom line I would probably just get an inverter large enough for what you want to run and make sure you had a good battery, the largest that can fit in there. The other advantage is if you had to leave for safety reasons in you van it is all with you.

The other option would be a Honda 1000i inverter genset, very small and quite and light. It's speed changes depending on load. I would prefer the 2000I, but it's larger, which might make it more difficult to handle.