sine wave inverter???

Bad idea Terribly in-efficient to run a 200kw engine to run a 1.5 kw power supply. You can buy a cheap 2000 watt generator for less than the cost of a tru-sine 1500 inverter and save a lot of fuel besides.

Hi Clare,

How many KW am I using just idling?

-T

Your 3 liter v6 takes about 5kw to idle.(being EXTREMELY optimistic) The 100 amp alternator puts out about 1500 watts at full output, and takes almost 3 hp to do that - which is about 2.5kw, so you are using "about" 7.5kw of power to produce 1500 watts from the inverter - or "about" 6.25kw to produce the 720 watts required to run your furnace. And this is AFTER the engine has reached normal operating temperature, under ideal conditions. Add to this the fact the engine is only "about" 30% efficient AT BEST - and you are running this 3 liter engine severely throttled, and the real world power consumption to run your 720 watt furnace is well in excess of 10kw.

So you can realistically run a 6000 watt generator at better than 50% load on the same amount of fuel (assuming a recent model OHV genset).

Excellent analysis. Thank you!

I keep thinking of a whole house natural gas backup generator, but I can't afford one.

Not a good idea. Your car wiring can only handle 10 to 20 amps which means it can supply a maximum of 280 watts of power or more realistically, 100 watts or so. You should be able to power a cigarette lighter for short periods of time.

How much amperage can a good set of jumper cables handle? My guess is that it would be around 50 A. At 14V, that would be around 700 W - for short periods. My guess is that your alternator would overheat and be non-functioning in 20 minutes or so. Of course, that's just a guess but I'd say that your goose is cooked.

A GOOD set of booster cables can handle 200 amps. A cheap set can handle 100 for a short time, or about 50 steady. A cigarette lighter plug can generally supply 20 amps. On some vehicles 30.

At 60 amps,(720 watts) mabee 20 minutes and still have enough power to restart the car.

Hi Clare,

You have convinced me away from an inverter as a long term solution. However, I was looking at it only as a short term solution.

Where I would be using it would be once every four to five years, for about 1/2 hour four times a day for four days.

I already have to do maintenance on my car. A generator, taken from long term storage, is most likely not to work anyway. All the gas line would need to be de-gunked, etc.. This is why I was think of the inverter for the short term. I can always go rent a generator from another town (all the local would be out.)

My engine is a straight 4. Can you make an estimate as to how much gas I would be using running the inverter 4 times a day for 1/2 hour?

Many thanks,

-T

I am presuming an inverter would be permanently mounted inside the engine compartments. No jumper cables involved. What am I missing?

I wasn't presuming this. My recommendation is that you mount some alternators to some rollers in special boxes to take the power off from the drive tires. My guess is that you'll need to cool these babies down with big heat sinks and fans.

It COULD be - connected with battery cables like used to connect the starter

What kind of Subaru has a "straight" 4??? You would most likely burn out your alternator. Get a generator and drain the fuel system TOTALLY. Keep fresh fuel available (rotate to keep it fresh) and the generator WILL start - every time. Or convert it to propane and/or natural gas using the motorsnorkel kit from US Carb.

Don't waste the effort and money on the inverter which will NOT do the job.

Hi Clare,

Thank you. Do you have a favorite sine wave generator? One that runs propane?

-T

ALL generators (alternators) produce a sine wave. Overloading them causes the sine wave to distort - worse on some cheap units than others. I just bought a Champion 9000/7200 watt unit - bigger than you need. You do want one with an active voltage regulator - a lot of the cheap little ones do not. Yamaha generators are available ready-converted from US Carburetion, or you can buy the conversions from them for most common-brand generators. Can't go wrong with Honda if you have the bucks. I thing the 3000 watt Champion would do the job - buy the motorsnorkel conversion from US Carb.

I'm converting mine for both propane and natural gas (uses same conversion kit) so I can connect it to my home natural gas supply.

Thank you!

My advice is to forget it. Buy yourself a nice little Honda EU2000i generator. Keep five gallons (two good 2.5G cans like the No-Spill 1405 work well and are easier to handle than one big can) of high-quality fuel around and a couple of times a year dump it into your Subie and refill the container(s) to make sure that you have clean fuel available. Run the generator every now and then to make sure that things don't get gummed up. Your total outlay should be < $1,100 and you will have reliable efficient power to keep the furnace and refrigerator and tv and computer working for a long time if the power fails. Just make sure to put the generator _OUTSIDE_ away from windows and doors and air intakes and use a stout extension cord to bring power inside (unless you are feeling suicidal).

Thank you!

You would have to set the revs up maybe 3k just to keep up current.

Greg

That's what I do except my generator is a bigger, cheaper model and plugs into a transfer panel. It handles my oil furnace, well, a couple of small freezers and refrigerator as well as computer and TV and some lights.

Did this 8 years ago at cost of ~$1,000 so it would be near double today. Gas with stabilizer is cycled through my Subaru, lawn mower and snow thrower every 2 years.

Used it yesterday after a power failure. I had waited 3 hours as wife and I were in and out and damned if the power did not come back on a minute after I started the generator. It is nice to have the security of a generator as if power had stayed off, it's only 1 deg. F today. We've had power failures that have lasted as long as four days.

Wish I had spent money for the much more expensive Honda as my generator is noisy. The Honda dealer gave me a lot of advice as to what to look for in a generator other than a Honda and mostly advised not to get something real cheap like from Harbor Freight as if it breaks down, parts may be hard to find.