Introduction: Save Electricity With Your Gas-guzzler

Picture of Save Electricity With Your Gas-guzzler

Ok, so we all know that you couldn't possibly be using all that power that your 5.4L Truck, or your 5.9L Van is making, but then where is it going? And how can we reclaim some of it? In this Instructable I will show you how to save electricity, and also be ready in case of an emergency.

Step 1: Supplies

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Ok now we will need supplies

-Truck, car, van, riding lawnmower (no, I'm not kidding, some of them actually have 12v sockets!), etc.
-Battery jump starter/ battery booster pack/ rechargeable 12v battery thing (with cable to charge in car)
-12vdc to 120vac power inverter (mine is only 200watts)
-Lights, chargers, other things that use power (must total less that inverter's output, watts=volts x amps)

Total cost should be about $25,000, or only about $15-40 for inverter and jump starter.

Step 2: Charge It Up

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Next time you go out in your car take the jump starter and plug it in to charge. This is only effective if your commute is over 10 minutes long. When you get somewhere or turn off the engine UNPLUG IT!!! Most cars don't turn off the 12v cigarette-lighter port until it is too late and your battery is dead. If it is, then use the jump starter to start your car, but if you do it will drain it, making all of your efforts wasted.

Step 3: Power It Up

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Now that the jump starter is fully charged take your inverter and plug it in to the jump starter and turn it on. Plug in some 120vac equipment (less than the inverter's capacity, mind you) and tell the electric company to go ~~screw themselves~~ bill someone else. This method is great if you have a laptop (my MacBook's charges uses only 60 watts, versus my desktop computer that sucks over 500 watts), or other small things, like ccfls, or a small stereo (IDK if my technics will work, but my altec-lansing speakers are fine). If you happen to have the car chargers for your stuff, use those instead, because there will be less power wasted in the inverting process. If you live in a small apartment, you may even be able to power all of lighting off of this.

Another thing to remember is that you will still have power during outages, and also that this is pretty portable, meaning you can take it camping or on a picnic or barbecue.

Step 4: Thats All Folks!

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That was pretty simple, huh!
Now you can use that wasted gasoline (or diesel) to do something good for you, instead of just polluting. I'm open to ideas about how to improve, so please post a comment.

If you have any questions feel free to ask. I'm usually on here a few hours a day, so I can get back to you pretty soon.

If you liked my instructable, please rate it. Thank you!


bballman2888 (author)2010-11-20

You could use a larger inverter to power just about anything you want. I have a 16000W peak 8000W continuous running inverter i use with my marine battery instead of a generator. I mostly use it to run my 7" angle grinder out in the woods when I'm runnin scrap metal. works pretty good. People need to be careful though because most inverters out there are modified sine wave and are a lot harder on electronics. Pure sine wave inverters (the really good ones) almost match the wave frequency of the power you get from the utility company, but they are normally much more expensive.

twocvbloke (author)2010-08-16

A better tip:
Buy a vehicle that is actually more efficient, rather than something with an engine greater than 2 Litres, that way you get more power to the wheels and less waste out the back end... :)

PhantomOfHeat (author)2010-06-08

It might work out better getting a second battery from a junk yard and charge that with a disconnect switch and a voltage monitor to see the charge and the capacity should be larger than the jumper pack. If the kill switch is ran in line with a relay that has the on field switch ran to the acc on it will prevent it from charging when the engine is off with the key out.

Roger4Wheel (author)2009-10-13

For those of you who would do this in lew of buying a backup generator (for cost or whatever reason), you could do the same thing with a rebuilt automotive alternator (under $50.00 for my Ford) and a regulator.

Just hook them up to your lawnmower.  If it's sitting on a smooth survace (not mowing grass) the 5 hp or greater gasoline motor will easily charge a car battery, and probably more efficently than the full size V8 in the truck.

Of course if you don't have an appliance with a gasoline motor (mower, rototiller, powerwasher, etc.) then this tip isn't for you.

vtvtvt (author)2009-04-17

Using a car engine to generate electricity with it's alternator to charge a jump starter will cost far most in gasoline that it would cost to pay the electric company for electricity to do the same job. At least 3 to 5 times as much.

NRen2k5 (author)2008-09-25

- I think this'll ever-so slightly reduce your gas mileage, so technically you're kinda paying Big Oil rather than the electric company. - The items you used in your demo aren't big energy suckers either. The real big ones are your washer and dryer, TV, oven, toaster, coffee maker, microwave... generally anything with a heating element or a fairly powerful motor... These all draw more than 100W (some of them much more) - Booster packs are meant for just that: boosting - a very short and heavy current draw. They shouldn't perform amazingly for this sort of long duty cycle, low-current use. - Still, looks like a good idea for emergencies.

aaronjehall (author)NRen2k52009-02-01

Good point. Living in the north, I've been planning something similar to this using my 1981 Chevy work van. If the power goes out in the winter, it sucks. Problem is, I need over 1500 watts; most heaters of any count being 1500 watts. My plans did not include the portability of a battery box, tho. I just wanted a makeshift mobile home to sleep and keep warm in.

LinuxH4x0r (author)aaronjehall2009-02-02

Some of them can be plugged directly into 12v power and still work.

Derin (author)2008-09-06

ahhhhh in the hardware store everything i want is miles off my cash range i have about $100 but all the good stuff is more than $150!D:

aaronjehall (author)Derin2009-02-01

Yeah... How much would a 1500w power inverter be?

LinuxH4x0r (author)aaronjehall2009-02-02

Around $100

Grey_Wolfe (author)2008-06-25

It's too bad the vehicle wastes like 80 percent of the fuel, too. (Well more like 82%) But a nice way to save a buck or two, as long as you don't kill the alternator.

Derin (author)Grey_Wolfe2008-07-14

most alternators are rated for 100A,some truck ones may force 200A

aaronjehall (author)Derin2009-02-01

You can always get an overrated aletrnator as well, like what a car with a high watt stereo system would need.

LinuxH4x0r (author)Grey_Wolfe2008-06-26

Yeah, it only gets around 18. I don't think it puts that much load on it to kill it, or even shorten it's life.

jimpsolar (author)2008-07-30

I see here that jasonfehrs states you will use one hp per 25 amps. Can we take this one step further and calculate into amount of gas per amp? Not sure why this is so because the alternator is always turning. Where does the extra resistance come from when it is charging? I plan to setup a couple of marine batteries and charge them up on my 30 minute commute and then plug a cord and power strip from my house to the car at night and run a few small power items. Lights radio etc. This may sound like a pain for some people to do but we need to do something. (its a pain to dig into my pocket for money to pay for energy) I look at my vehicle in a new light, both for transportation and power generation.

xaenon (author)jimpsolar2008-12-08

The alternator creates magnetic fields in both the field and stator coils, which tend to resist the movement of the stator. The harder the alternator works (ie, the more current it must produce), the stronger the fields and the greater the mechanical resistance. In the days of carbureted cars, you could actually hear the engine's idle speed drop when the alternator went under a heavy load - like when jump-starting a car with a dead battery, for instance. Modern engines with their electronic controls can adjust idle speed to compensate for various loads, so it isn't as noticeable any more.

nubie (author)2008-12-08

If you want to save energy you can use a drive-shaft mount alternator to charge as you coast or stop:

Normally used on hot rods or racing vehicles, you can put a closed throttle switch on your vehicle that will turn the alternator on only when decelerating. This would use truly wasted energy that would otherwise be converted into heat by the brakes.

LinuxH4x0r (author)nubie2008-12-08

Sounds like a good idea for the electric car I'm working on

Rishnai (author)2008-05-04

I knew a guy once in Arizona, never hooked up the utilities. He had a bunch of brake lights on a string that he hung around the living room like Christmas lights, and at night he would pull the battery out of his truck and hook them up. Lit the whole room. Once he'd done a little reading and his kids had played a little, they disconnected it and went to bed. He had a little generator that they ran once a day to chill their fridge, then kept it shut all day except for one flurry of motion when his wife would pull out all the fixin's for dinner, and then cook it on a camp stove. A little off the wall maybe, but they were nice people.

Grey_Wolfe (author)Rishnai2008-06-25

I live in Arizona, lol. Not an overly bad idea, cept maybe the fridge. Well have to get the seals around windows and doors a bit better before we go killing the swamp though. That's Beverly Hillbilly livin' there. lol

LinuxH4x0r (author)Grey_Wolfe2008-06-26

Maybe you could make a solar ice maker...... I'm going to try to make one sometime

Grey_Wolfe (author)LinuxH4x0r2008-07-15

I haven't thought about one of those in a long time. Excellent idea, thanks. Have you been able to find any good plans? Maybe here on the site?

Grey_Wolfe (author)Grey_Wolfe2008-07-16

What about using one as an alternate to a standard condenser to make a more green AC unit?

Rishnai (author)Grey_Wolfe2008-06-25

One nice thing about Arizona is that ya'll get a dry heat, so swamps work. Here in Colorado they usually work, but this year it's been too damn wet. It's like I'm back in Misery (Missouri).

You shoulda seen the summer me and my dad's family spent in a settler's cabin, with all the original 1960s features, including hot and cold running vermin. That was hardcore hillbilly.

Grey_Wolfe (author)Rishnai2008-07-15

I didn't notice the 'hot and cold running vermin' part before. But it make me feel warm and fuzzy. lol

Grey_Wolfe (author)Rishnai2008-07-15

That 'dry heat' thing is only partly true. Right now the thermostat's reading 80 (in the cool part of the house), and the swamp's yet to be turned off in the last few weeks. But that's the way of monsoone season here. We're running about 40% humidity during the day right now. Nowhere near Missouri, but enough to make the swamp fairly ineffective. But during about 8 months of the year, the swamp does work pretty good. And it's much cheaper than AC. Costs me about a third to cool this house compaired to my mobile, and at three times the footage.

Rishnai (author)Rishnai2008-06-25

Oops, 1860s, not 1960s.

jasonfehrs (author)2008-05-26

Although not very important in such a big engine as you mentioned (5.4L, 5.8L), it is worth noting that the more electrical power that is generated by the alternator, the more horsepower the engine with be derived of. An alternator typically takes about 1 HP (horse power) for every 25 amps of power generated. So, a 100 amp alternator will require about 4 HP at full output. Most alternators do not operate at full output for very long. Not a very big strain for a large engine, but a big consideration for the compact crowd with engines only outputting around 100HP. Another thing to consider is that the AC compressor typically using around 10 horsepower. As we all know, the more horsepower that is starved from the engine, the more gas you use.

itwasalan (author)2008-05-15

I was thinking of something like this the other day. Nice work. I'm off to the auto parts store.

LinuxH4x0r (author)itwasalan2008-05-15


matseng (author)2008-03-08

Sorry, this is so incorrect. Where do you think the energy is coming from? Right. It comes from the generator/alternator that's driven by the engine. If you put an electrical load to the alternator it becomes harder to turn it. And that in means that the engine must work harder. And if the engine must work harder it will need more gas. So what have you gained? Nothing. You will just pollute the air even more than before. The cost per kilowatthour will be higher this way than using the mains at home. If you want to save a lot of energy in the car, just turn off the AC. At home lower the temperature one degree (if using heating) or raise the temperature one degree if (cooling).

killerjackalope (author)matseng2008-03-08

Did it occur to anyone that the alternator doesn't affect the load on the engine much, I actually got a chance to see this in action when we had to remove a bum alternator from a pickup truck we ran about in (harbour only) the milage didn't change despite the fact that we had the alternator on all the time, under full load there's a tiny difference compared to unloaded, the big difference comes from when the alternator isn't engaged at all to when it is, also seeing the charge amounts on the artificial horizon makes it all a bit more obvious, we could plug in the inverter and be running ~100W and there would be no change in the charge voltage (readout showing power going to charge the battery). Basically becasue either way the alternator is putting friction on the belt it won't make a difference unless you remove it altogether, that changes it by 1-2mpg from what I saw in a semi efficient pickup (smaller diesel). However there are ways to get cheap energy out of the car, some are simple ones that can be obvious like cooking under the hood or extremist exapmles like adding large magnets to the rims and coils in the body...

Thank you! Finally someone that gets it! Its just charging a small battery, not running a saw. It slowly charges it, not some sudden load. I think you are the first person who actually gets it. Thank you.

PKM (author)LinuxH4x0r2008-03-08

An alternator under electrical load is harder to turn than an alternator under less electrical load, because it is producing electrical energy which has to come from somewhere. This fact is not open to debate. I have seen small-engined motorbikes actually stall when the headlights were turned on, from the additional 40W or so of load on the alternator.

The engine produces this energy, and will therefore burn more fuel. This fact is also not open to debate.

A less clear point is whether the engine will use proportionately more fuel, because it's conceivable that the engine is more efficient running slightly harder than it does normally.

Nevertheless, 1 Joule in the battery will need at least 1 J from the alternator, which will need at least 1 J from the engine, which will need at least 1 J of fuel. (Bear in mind ICEs are about 10% efficient, and there are further losses in the alternator, battery charge/discharge cycle and inverter, so 1J of electricity used by your mains appliance will need something more like 20J of fuel)

You aren't getting "something for nothing" here, you are just using your car as a generator. In this country, electricity costs about the same per Joule as petrol, but as stated above you have to use about 20J worth of petrol to generate 1J of end-point electricity. It is also much, much less efficient in terms of fuel use and CO2 emissions than mains power. This might end up cheaper for you if you have ridiculously cheap fuel and ridiculously expensive electricity, but it is definitely worse in terms of global fuel use and emissions.

To the people saying "the alternator doesn't affect the load on the engine much", that's because the power used by the engine anyway is a couple of orders of magnitudes larger. All the lights, ignition system and battery charging on a car may use a few hundred or even over a thousand watts, but bear in mind that 150HP is nearly 112 KILOwatts. You clearly won't see much of a difference in your gas mileage if the difference in power consumption from the engine is of the order of 1%, but just because the difference is proportionately small doesn't mean it's actually small.

To killerjackalope: adding magnets to your wheels and coils in the car body will turn your wheels into (very inefficient) alternators, increasing your fuel consumption a lot for a small quantity of electricity- it's like putting solar panels in front of your headlights to recharge your battery by "catching the wasted light".

Sorry to sound combative, but I wish people would listen to those with enough formal training in physics to uinderstand the complexity of issues like this rather than blindly arguing on their gut feeling of how they think engines "ought to" work.

nerys (author)PKM2008-04-10

Well your not quite right on the magnets in the wheels idea. Your only right if you have it "ON" all the time. I would HOPE the idea is a crude form of regenerative braking IE you turn it on when your coasting or braking. Now the question there is does the increased MASS of these magnets and coils and therefore increased LOAD on your engine to move that mass exceed the amount of energy you will recover and what will you DO with this energy? It might be interesting to use this to REPLACE the alternator and gain back a mpg or two from the engine. but driving habits now come into play IE would you "stop" enough times to recharge the battery before it dies though I guess a small computer could just engage them whenever the battery gets to low. You would take a hit when your going but still have some gain each time you stop or coast. Question is how much. Your were not combative but your last statement was stupid. Many of the worlds greatest inventions come from those with NO formal training. You should ENCOURAGE people not tell them leave this to the people who know. NOW they (those without formal training) should keep an open mind on it and they should listen. Arguing is GOOD. it helps people to work through issues. If he just blindly accepted your information he learns NOTHING. If he argues with you and you argue back and eventually he gains enough knowledge to go OH now I understand THATS why it won't work. Who knows what he might come up with next. You just INCREASED his knowledge repository. Listen to me I know better DOES NOT HELP :-) NOW on to the user. First out electric grid is one of the most efficient sources of energy as far as a watt per dollar is concerned in the USA. IE we have VERY cheap electricity for the most part. Thats why electric cars would kick ass! Electricity would net me 100 miles of driving for $1 in electricity!! right now going a hundred miles on gasoline costs me AT LEAST $13 of diesel in my 300D or $15 of gasoline in my minivan or worse yet $27 of gasoline in my big van. Add in some solar sold back to the utility and I could drive for FREE with an electric car after initial purchase.\ Everytime you convert you LOSE something. Using E to charge your battery will ALWAYS be better than using OIL to run an ENGINE to run an alternator to Charge a battery. unless your can make your own oil cheap them that might be better (but still less efficient always) This is not about the load factor killerjackalope its about COST. YES the load increase on your engine to charge that battery pack is MINIMAL but the WORK you can GET out of that battery pack is ALSO minimal and it will STILL cost your more in electricity than it will in gasoline. If you have a 20amp battery at 12v thats 240 watts. That means it will cost me (ignoring charger efficiency losses) 3.2 CENTS on my electric bill to use the same amount of power as there is in the battery. I guarantee you that it will cost your more than 3.2 cents in gasoline to charge it in your car. Thats 0.0106 gallons of gasoline. BREATHING on your gas pedal will use more gasoline than that :-) SO unless you can get more than 240 watts out of your alternator on .0106 gallons of gasoline its cheaper to just PLUG IN whatever it is you want to run. Plus to run all the small things in your house your gonna need dozens of these boxes. Now we are talking a hefty investment AND you would need to be doing a lot of driving as well. I drive 54 miles each way to work thats about 90 minutes each way or 3 hours of "engine time" per day. These jump boxes usually take over 12 hours to charge that means 4 days of driving to charge the jump box. NOW if you have some VERY lower power applications where it runs for DAYS on a battery NOW you might have some options. TWO batteries. ONE on solar power one running your gadget. When the battery dies you SWITCH so the dead one recharges on the solar power (it will take DAYS to charge thats why you need devices that are very low power) There is still the issue of consumables. IE those batteries will NOT last forever. Will the cost of those batteries EXCEED the cost of the E you saved by using them? My cell phone needs 3.7 watts of power per day. so in a year I will use 1350.5 watts of power from the grid. thats 18 CENTS worth of electricity. Do the math. lets say i charge 4 cell phones an ipod and my ebook reader all same battery so 18x6 or $1.08 cents of electricity PER YEAR If I use one of those USB Gizmo's from walmart for $10 I can run the rig off of AA cells. so that means I will need 8 cells but I can not use AA cells they max out at 2600mah thats only enough to charge 2 of my 6 devices. I need 6 amps of power or 6000mah to charge everything plus overhead. They do make 12amp D cells but they are very costly $45-$50 for 4 of them and we need 8 so lets go with the 10amp cells at $6 a pop thats $48 for all 8 See the problem here yet? we have NOT even purchased a solar panel yet and already we are at $60 in batteries and power supply. Lets ignore the power supply and just look at the batteries. NIMH batteries are good for around 800-1000 charge cycles. Your going to run it at least 180 times a year. (two sets of batteries so half duty cycle) The ONLY way you can break even if is they last longer than 45 years. There not. There going to last 3-4 years at this duty cycle MAX. 5 if your lucky. No way in hell are they going to last 45 years and you have not even purchased the solar panel yet. and since we are limited to 10amps you need a panel that can charge those batteries in under 8 hours of daylight! a 45watt cell should do it thats $139 on sale :-) Where switching power comes in as a benefit is when we are talking MASSIVE amounts of power. Such as with an Electric Car :-) Saving money on E usage is better if you REDUCE power not CHANGE power. For example put all your little chargers on a power strip so you can TURN THEM OFF when your not charging anything. This will save you far more money) though still measured in CENTS per year. Want to really save money? Switch to CFL throughout the entire house. OR LED if your willing to do the work to set them up right. Payback on investment is around 1-2 years with this route (IE thats how long they take to save you an amount of electricity equal to the cost of buying them) Hope this helps

membrane (author)nerys2008-05-05

On the subject of switching lights go with CFL and get the good ones . LEDs are good for task lighting but CLFs are far superior for area lighting. A good way to see how efficient a light really is to look a number of lumens this is how much light the bulb produces then compare this to the watts used. A typical 60 watt incandescent produces 1100 lumens a 13 watt CFL about the same. Most so called LED bulbs only produce around 200 lumens but use 4 watts of power this compares unfavorably with CFLs

nerys (author)membrane2008-05-05

Under "equal" circumstances you would be correct. Build an LED lamp that produces light in the same manner as a CFL and the CFL would win hands down every time. Alas your not right because they do NOT produce light equally. CFL has a similar problem (or perk depending on circumstances) to Regular bulbs. the Light produces is OMNIDIRECTIONAL. While LED light is almost completely unidirectional. Compare the LUMENS to WATT ratio of LED to CFL but Limiting the "counted" light produced by the CFL to the same narrow unidirectional band as the LED array. Now suddenly CFL does not fare so well any more. NOW if you NEED unidirectional OK CFL is better BUT if you can arrance more unidirectional light to WORK for you the LED will use FAR less power for the same "effective" light produced. IE "usable" light. I have my room rigged with TUBES of led lights along the edge of the ceiling taking distinct advantage of its unidirectional nature. Now since this causes "shadow" issues I have LED's on opposing walls as well (IE all 4 walls) This gives me an almost completely "even" illumination of the entire room. Instead of it being VERY bright at the sources and dimmer and dimmer as you move away. If feels like daylight since its light "all around" with no apparent source just based on the illuminations levels in the room. My room is lit by 1600 LED's and consumes a mere 27watts of power. Lets see you light a room this size effectively with 27 watts of CFL (2 x 13watt CFL's) (its a decent size room) I used to use two 150watt halogen floor lamps. The roof is MANY times brighter now than with the halogen. Now when you have a CAVERNOUS space like a garage. OK you need that omni directional blast of light that only 4x20watt CFL's can provide. I mean LED's could do is and still use less power but the COST of the number of bulbs you would need is still currently excessive for such an application. YOU HAVE to compare them with there specific properties in mind. Stick a CFL in the corner and more than 70% of its lumens is WASTED blasting the two walls ceiling and table that they reside on with unneeded light. a very small amount of that light actually gets put to work to light up the rest of the room. its not JUST the lumens but HOW you use them. IE Effective Lumens.

LinuxH4x0r (author)nerys2008-05-06

You can diffuse them... or use a lens. Its like saying that my truck is less powerful than my car because the clutch slips. Its not how efficient it is its how they are used.

nerys (author)membrane2008-05-05

One more thing you forget is LIFESPAN. I have to replace the CFL's once every 1.5 to 2 years. I should in theory NEVER have to replace my LED lamps in my entire life time.

killerjackalope (author)PKM2008-03-08

My point is that when the engine is actually being used to drive the load difference in the alternator is much less of a factor, I know that energy is coming from somewhere. When you are actually driving along though the difference in alternator load will result in cheap energy, even when cruising you're talking about ~1mpg for a smaller engine, in a big powerful engine this idea works well, In an uber efficient car it wouldn't be a great idea but to put the idea in perspective our rodea (3.0L diesel) ran on £25 a week in diesel doing the same thing day in day out, AC on it ran on £26 a week, I use that as an example as the AC compressor puts on more load than an alternator... It's not about free energy and had linuxh4x0r said this was true of all cars I would disagree but with a large engine there's more freedom up for grabs. I have noted the difference as my dad and I tested this thoroughly using the AC, at idle when you switched the compressor on the revs went from 750 to 800 rpm (Idled very slow). On a smaller car like say a 1.4 or some such, this idea would have a bigger knock on effect as there's less spare power for moving the car. The magnets on the rims was more a joke than anything else, that said putting magnets around the prop shaft and a coil around it would result in an alternator of sorts that wouldn't give much bother, the idea is more an impractical joke, if they made magnets that were as dense as styrofoam and had incredibly powerful fields then it would be a nice idea... I understand the complexities of this issue and was just pointing out that there are times that such an idea are economically viable, maybe not good envrionmentally but could save a few pence of electricity. As far as portable electricity goes this is a great idea, especially if it was used without and inverter and current limiting circuits instead to power 12V devices. If engines work the way the 'ought to' we'd all have sunbeams and rainbows coming out our exhausts wouldn't we...

Totally agree. This is on a 5.9 and a 5.4 liter engine. I don't think it has any problem putting out a few extra watts. The portability makes it worth it, even if it uses a little more gas (not saying it does)

nerys (author)LinuxH4x0r2008-05-05

we are not talking a few extra watts. We are talking well over 10,000 watts at 120v per 100 miles. Thats a lot of watts to your 12v alternator :-)

Ohm (author)LinuxH4x0r2008-03-08

Just get a big alternator and at higher current draw it wont put as much load on the engine.

LinuxH4x0r (author)Ohm2008-03-08

The one it has now is more than enough! This thing is huge.

nerys (author)killerjackalope2008-05-05

Well not really. the alternator is capable of applying a significantly larger load than your AC is. The issue is not load but the LOAD your likely to apply to it. I connected a 2000watt Inverter to my van to run my freezers when the power was out. I tried to run BOTH freezers. While this did not even PHASE the inverter (they draw 6 amps MAX DRAW It almost stalled my car when the alternator tried and FAILED to supply this load. In fact the only reason the engine did not stall was the alternator could NOT keep the voltage above 1v the minimum for the inverter so it shut down releasing the load. That was just 12amps and this is a V6 3L 158hp engine. Even doubling the RPM of the engine could not maintain the load. And thats a TINY 60amp alternator!! Imagine the load a say 160amp alternator would apply to that engine. The load of AC is actually quite small in modern cars. your BLOWER motors on high produce a higher load via the alternator than your COMPRESSOR does via the pulley on anything except tiny cars. Before I upgraded the alternator in my clubwagon I could NOT put the blowers for the front and rear air both on high without a massive drawdown of the battery as it maxed out the alternator (since installing the PROPER 165amp alternator that was supposed to be in that van the problem has went away but I can still see a HUGE drop in the volt gauge when I ramp up both fans while the AC compressor is a minor load.

The point is that this method uses a lot more energy (and money) than just plugging it into the grid.

membrane (author)PKM2008-05-05

Actually ICEs are 22 to 25% efficient though some very large diesels ie trains and ships can approach carnot limits when operating at a full load and produce energy efficiency numbers of over 45% Your typical coal or natural gas fired plant in the US is about 50% efficient.

tanntraad (author)PKM2008-03-09

You said it. So true

Remember this is viable with big engines and vehicles, not so much with little machines, the ride on mower would definitley not work, they're not wildly efficient... Sure some trucks, volvos in particular have an airline under the dash which runs off a small compressor that usually operates the brakes for the trailer, that's an economical idea because it saves weight and complexity issues...

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