Is there something I can drive my trucks’ drive tires onto that I can generate mobil electricity with at idle? This would be a very quiet generator and maybe cheaper since it has no motor of its own and more reliable, I hope its out there and is practical??
Wouldn’t a power inverter be a more standard solution?
Of course, all commercial cars have a self-charging electrical system built in so 12 volts are already available. Nanoda has the solution for 120VAC power.
Are you talking about some kind of ‘rolling road’ device that would run a generator from the rotating wheels of the vehicle?
I’m sure somebody out there has probably made such a device at some point, but it seems to me that there are a number of practical reasons why such a contraption wouldn’t make it to market:
-It’s going to be big and unwieldy
-It (more or less) requires you to exit the vehicle while it is still in gear with the engine running.
-If the engine is running at idle, adding an electrical load to the output is going to result in an increase in generator drag and the vehicle would probably stall - standalone generators have a feedback mechanism that increases the throttle to (try to)maintain constant revs under load.
-If the engine didn’t stall under load, the vehicle might actually drive itself off the rollers.
-Ditto (even more so) if it is required to rev the engine - any change in wheel revs or load torque is going to tend to jump the vehicle’s wheels off the rollers.
-There already exist much simpler solutions - vehicle+inverter or standalone fuel-powered generator - the latter of these two is still probably going to be a more compact and portable device than a rolling road.
Assuming that you mean whent he car is stopped and idiling, the wheels won’t be turning, so anything you attach to the wheel/tire won’t be turning and generating any electricy.
Power inverters are available that will generate 120V from an alternator. I have seen them work with various levels of sucess.
I think he’s talking about powering his house during an electrical power failure. Generators are very loud and annoying. If a hurricane knocks out your power, you have to put up with all the noise from the generator if you want juice.
A device that was like a generator attached to some free spinning wheels (like the kind those things have that let you ride your bike indoors) that you could back the truck on to. Then you could put the truck in Drive and let it idle. The tires would spin the free wheel thingies which were connected to the generator. The running engine of the truck is much quieter than most generators on the market.
There would have to be some gears and chains I bet. To make the generator spin fast enough to get decent power out of.
An idling truck engine is quiet, true. But that’s because the engine isn’t doing any work. Of you hook it up to a generator and rev it up enough to produce power, the engine will be much louder.
It’s true that 12V -> 120V inverters do work well. But they’re usually not rated for very much wattage: 850W is the largest I’ve seen at the local electronics stores, although I’ve heard, rarely, of inverters going up to 2kW. You microwave one burrito on an 850w inverter, and it’s overloaded, at least using my 1100W microwave - let alone running lights, refrigerator, TV, or what-have-you at the same time. And you certainly should not plug such an inverter into your cigarette lighter - drawing 850W would pull a current of 70A through the wiring to the lighter, at 12V. You’d have to wire it directly to the electrical system of the car.
And then you have a longevity issue. Most car alternators are rated for around 100A (often less, occasionally more) at 12V. That limits your continuous power consumption to about 1200W, neglecting the electrical power consumed by the car’s ignition system, etc. Use more than that, and you’re relying on the energy stored in the battery to make up the difference. Obviously, the battery does not have an infinite capacity.
The advantage of the “rolling road” generator is that the amount of power available to such a device is much, much greater. Let us suppose that a typical, economy car can deliver 100hp at the drive wheels, with the engine revved to the peak of the power curve. Actual horsepower output at idle is much less, so let’s assume that the idle RPM is equal to about 1/4 of the peak power RPM, but that the efficiency of the engine at that RPM is halved. 100hp is equivalent to 74.6kW, so let’s say that, with the accelerator held down enough to maintain the idle RPM under generator load, we might see 1/8 of that amount, or 9.3kW, at the wheels. If the generator mechanism has 75% efficiency, we might extract a usable 7kW of electricity. This should be more than enough to power your own home, and that of your neighbor as well.
Depending on the truck, you may be able to fit a PTO (power take off) to the transmission, and either drive a generator directly or through a hydraulic system.
This solution is fairly common on fire and rescue trucks, where they run those big flood lights that illuminate the scene. The assumption being that events that require the trucks to be on location are also likely to have knocked out electrical service, even if were normally available.
If your truck is larger than a 1/2 ton pickup, there is a good chance a PTO is available. Muncey and Chelsea (spicer) are the main players.
As for noise: Rule of thumb would be about 1 HP per KW delivered. 5KW is significant electrical power, but a 200HP truck engine isn’t going to make much more noise than idle to provide it.
That sounds a bit off - I don’t know the efficiency of a typical generator, but even at 100% efficiency, 1 HP is about 3/4 kW.
Ack, your right…I seldom have to go that direction. With effiency losses, and a little elbow room, 1KVA is needed for a 1 HP motor. With losses running the other direction, make that a little under 2 HP needed to generate a KW
I always thought it was 740Watts per HP…
It would be very cool to roll your van or truck onto an apparatus of some sort and power your pop-up trailer out in the mountains or wilderness! Bacon and eggs breakfast, browsing the SD site on satellite connection , A/C… that’s how to go camping! I will look into that direct link into the tranny thing, my bro and I are in the beginning stages of purchasing the vehicles and equipment needed to do just what I envisioned… I am pretty sure power inverters and battery power are impractical solutions… I have heard you can build boxes for portable generators to make them quiet but I am just checking into all the options.
Why reinvent the wheel?
Powerful 12 volt inverters are readily available in a range of provided powers and at fairly reasonable costs. The last one on that page is 6000 watts. That should be plenty for most uses.
6000 watts from 12V, eh? That would be 500 amps. Can your car’s electrical system supply that? I know mine can’t.
Funny, I had an mental image of a steam engine run from the heat of a burning tire. You can use old tires as fuel, though there are major environmental concerns.
Not factory stock but the electrical service to many homes can’t supply 6kW either. The battery would provide the oomph during peak 500 amp draws. If you’re talking sustained multi-kilowatt, a generator is the way to go.
I think you are just asking for a world of problems. Not only will you have to hook up the gen to the engine somehow, but you will have to regulate engine RPM’s based on load, and I don’t think using the cruse control would be enough.
If you really want to do this, and don’t want to go for a seperate generator, the best way seems to be to beef up your trucks electrical system by adding a altnator if possiable, and making both high capacity and duel batteries. This should be fine for the 6000W inverter. Remember your microwave will only be used for minutes and the batteries can supply power when demand excced supply. Other appliances, require much more starting power then running power so should be OK also.
I still think the rolling road components are the big weakness in this idea - I was going to suggest jacking the vehicle up onto axle props, removing the wheels and fitting some kind of power takeoff to the hub, but this idea is made slightly more complex by the differential.
I have built one. I don’t have any dB specs, tho’. All I can say is it’s extremely quiet. The majority of the noise comes from vibrations (ie. the latch, or hinge, etc.) I wish I had some way of measuring the sound, but can only compare it to stuff. I’d say it’s quieter than our dishwasher (I don’t know where that is on the dB scale). If you’re interested, I’ll try to rustle up some pics when I get home tonight. I am ordering some Bquiet-Ultra to line the remainder of the box with this week. It should reduce the noise even further. (It’s a 2800 Watt genny… probably not enough for a house, but adequate for our RV A/C).
Adding a bit more, here.
Xantrax makes some BIG inverters, up into the 3KW range, I think. When I investigated it, I couldn’t find an alternator for my truck that could keep up with it. IIRC, you’d need something on the order of 3-400 amps to drive an inverter of that size (not to mention its cooling fans). Biggest aftermarket alternator I could find was about 160 amps, and it cost a fortune.
Next, I looked into a PTO system (my truck has a manual tranny, and a PTO port already built in). They’re available, but the cost was astronomical (to me anyway. 3-4K).
Since my goals were: quiet, 23 amps (minimum), and stealth (didn’t want something big and shiny in the pickup bed attracting theives)… I had to build my own. It’s permanently in the pickup and no one knows it’s there.
Lemme know if you want more info.