How my friend is going to blow himself up...

[jrbruin]

Power is not free. Therefore, if his contraption uses electricity, then it either comes from the charging system of the bike and therefore puts an additional load on the engine, using up more fuel. Or, it comes exclusively from the battery, in which case it will need to be recharged in some manner.

Since he's likely powering it from the bikes electrical system as a whole, then it is creating an additional load on the system and assuming that the system will maintain the battery at a certain level of charge, his contraption is, indeed, drawing a bit of power from the engine and using a bit more fuel. Granted, since he's generating a miniscule amount of hydrogen, he's loading the motor and using more fuel in the same miniscule manner.

The stator is going to produce the excess electricity anyways, it's just a matter of whether it's used to produce the hydrogen or whether it's dissipated as heat from the reg/rec. Either way, stupid idea, if he wants to use the excess electricity for something useful he should get some grip heaters or a gps...

 

[phuzzy3d]

 

[ST Guy]

The stator is going to produce the excess electricity anyways, it's just a matter of whether it's used to produce the hydrogen or whether it's dissipated as heat from the reg/rec. Either way, stupid idea, if he wants to use the excess electricity for something useful he should get some grip heaters or a gps...

Good point. I hadn't thought of that.

 

[GhostRider]

The stator is going to produce the excess electricity anyways....

Now, if we want to get all technical here....

.... but the stator does not "produce" excess electricity.

The load on the engine is directly proportional to the current drawn from the stator.

Load engine = Current drawn * Generator efficiency

 

[R6UCD]

He probably works for Buell.

 

[jrbruin]

Now, if we want to get all technical here....

.... but the stator does not "produce" excess electricity.

The load on the engine is directly proportional to the current drawn from the stator.

Load engine = Current drawn * Generator efficiency

Not sure about the hydrogen guy's bike, but on my bike the flywheel rotating around the stator creates an alternating current that is fed into the reg/rec and the positive and negative phases of the alternating current are combined to create DC voltage. This occurs whether I want it to or not, and regardless of how much current I'm drawing off the system. If I add accessories that are drawing power, my idle speed doesn't increase (ie. No load is added to my engine)... I've seen that happen in cars, like when you turn on the AC or whatever, but I've never owned a bike that would increase it's idle to meet the demands of the charging system. Do FI bikes do that? Maybe it's just that I've only ever owned carbed bikes?

 

[ST Guy]

Actually, now that you mention idle speed and load, I'm going to retract (or at least partially retract) my last post. I find that when I'm running my PIAA 910 driving lights and the engine is warmed up and it and the charging system are hot, my idle speed increases when I shut the lights off. My charging voltage also goes up as well because the load has been removed from the circuit. This would indicate that indeed, additional load on the charging system does load the engine itself and therefore use more fuel.

 

[jrbruin]

Hhmm.. I think it must depend on the bike. Neither bike I've owned has had an ECU, so they just put out a constant wattage regardless of system load.

 

[Roundboy]

hmmm

Harlydenburg

 

[ST Guy]

Hhmm.. I think it must depend on the bike. Neither bike I've owned has had an ECU, so they just put out a constant wattage regardless of system load.

Ah, the sweet mysteries of electrical systems. I think the British got it right when they used smoke in the wires.

 

[Burning1]

jrbruin,

Your car's ECU automatically increases your idle speed when you turn on the AC in order to compensate for the load. Placing a load on the engine will usually lower the idle speed, unless another control mechanism steps in to of-set it.

For example, certain old caruburators on heavy duty vehicles used to had vacuum based feedback system that would open the throttle a little further for you when heavily loaded (I.e. pulling a boat.)

 

[gixxerboy55]

Not sure about the hydrogen guy's bike, but on my bike the flywheel rotating around the stator creates an alternating current that is fed into the reg/rec and the positive and negative phases of the alternating current are combined to create DC voltage. This occurs whether I want it to or not, and regardless of how much current I'm drawing off the system. If I add accessories that are drawing power, my idle speed doesn't increase (ie. No load is added to my engine)... I've seen that happen in cars, like when you turn on the AC or whatever, but I've never owned a bike that would increase it's idle to meet the demands of the charging system. Do FI bikes do that? Maybe it's just that I've only ever owned carbed bikes?

From what i understand, most bikes don't even put out enough voltage to keep the battery charged below 3000 rpm. So in order to keep the system charged, you need to run above 3000 rpm, otherwise you are running off the battery. And yea there is no free lunch.

 

[arnoha]

Well, let's look at it this way:

Typical motorcycle charging system is good for around 300-400 Watts. 1 HP is 750 Watts. So, assuming that you can somehow magically use all this power (you can't, something has to drive the motorcycle's electrics) and it was somehow 100% efficient (not even close), you could only get an extra half horsepower out of it.

The reality is that even a tenth of that would be nearly impossible, and you will burn extra fuel to get it.

There is no free lunch, I'm afraid.

 

[Cycle61]

Hhmm.. I think it must depend on the bike. Neither bike I've owned has had an ECU, so they just put out a constant wattage regardless of system load.

Negative. The alternator puts out the wattage that is being drawn by the collective of all the loads on the electrical system. It has nothing to do with the ECU, it's just physics. As the electrical load increases (more wattage) the alternator requires more force to turn, thereby increasing load on the engine. There is no such thing as "extra electricity" in a system. If I have a 700 watt alternator, and I load it to 50 watts, it puts out 50 watts. If I then tap off an extra 100 watts to split some water, I didn't just get free power, I'm increasing the load on the engine by that amount, minus generation inefficiencies.

 

[Jakemate]

http://www.straightdope.com/columns...eage-using-your-alternator-to-make-browns-gas

I'll see your link and raise you scary plans.....

http://jlnlabs.online.fr/bingofuel/bgen/

 

[Zed10R]

jrbruin,

Your car's ECU automatically increases your idle speed when you turn on the AC in order to compensate for the load. Placing a load on the engine will usually lower the idle speed, unless another control mechanism steps in to of-set it.

For example, certain old caruburators on heavy duty vehicles used to had vacuum based feedback system that would open the throttle a little further for you when heavily loaded (I.e. pulling a boat.)

This makes sense to me. The air conditioning compressor is mechanical resitance against the engine, so the engine needs to burn more fuel to turn the compressor. logical. But when you attach electronic devices to a bike, like lights or whatever, I can't figure out how more lights = more mechanical resistance. Your electrical system puts out a finite amount of electricity...if you use it all or not I don't think matters one bit to the engine. Do you think turning on the radio lowers your fuel economy??? No...it doesn't. Like mr WR400....it has lights. When the engine is idleing, the lights are dim. If you rev it, the lights brighten. Now, no matter how many light I attach to the bike, It will not stall @ idle. The lights to not represent mechanical resistance. I might blow a fuse, though. If I were to install a bigger magnet and stator and all that, that produces more electricity and takes more force to rotate, THEN it would effect the amount of fuel burned.

If someone can create an electrically powered chemical reaction that creates more potential energy than the generator uses to make the electricity, they would win a prize.

 

[GhostRider]

I can't figure out how more lights = more mechanical resistance. Your electrical system puts out a finite amount of electricity..

FAIL


Just because you cant figure it out, doesnt mean this is not true.

I could explain the entire 7th grade physics to you, or - think about the analogy of a generator being essentially an electric motor running backwards.

on a motor, the amount of torque generated is proportional to the electricity you feed into it.

in the same way, the amount of torque needed to TURN OVER the generator is proportional to the electricity drawn from it.

 

[Zed10R]

FAIL


Just because you cant figure it out, doesnt mean this is not true.

I could explain the entire 7th grade physics to you, or - think about the analogy of a generator being essentially an electric motor running backwards.

on a motor, the amount of torque generated is proportional to the electricity you feed into it.

in the same way, the amount of torque needed to TURN OVER the generator is proportional to the electricity drawn from it.

OK smartypants. I guess in YOUR car, if you turn the radio on, your engine burns more gas. rofl

 

[sv_goon]

FAIL


Think about the analogy of a generator being essentially an electric motor running backwards.

on a motor, the amount of torque generated is proportional to the electricity you feed into it.

in the same way, the amount of torque needed to TURN OVER the generator is proportional to the electricity drawn from it.

Y'know, I'd been wondering about this very question for a long time. I appreciate the clarity.

subscribed

Cheers...

 

[Burning1]

OK smartypants. I guess in YOUR car, if you turn the radio on, your engine burns more gas. rofl

Zed10R,

Turning on the radio actually will reduce your fuel consumption, although it will be by an insignificant amount. Remember that the radio draws a very minute load compared to some of the other electrical devices on a vehicle (how long could you listen to the stereo with the engine off, vs how long could you leave the lights on before the battery dies?) In some cases, however, the stereo can have a real impact. Installation of sub-woofers and amplifiers may require the addition of a heavy duty alternator and capacitors to handle spike loads . In many cases, te sub-woofer can void the warranty on your alternator, because the high electrical demands can burn a stock alternator out.

Regardless, I think some experience with generators will help you wrap your head around this one. Generally, plugging a high load into a generator will have a significant impact on the engine speed. Usually RPMs will drop noticeably along with voltage until the carburator / ECU compensates by supplying more fuel/air mixture. You will not be able to stall a generator by placing too high a load on it simply because the alternator is NOT over-engineered for the engine driving it. Typically, they engine is capable of producing more rotational energy than the alternator is capable of converting into electrical energy.

On a car, you will not be able to stall the engine by turning on extra lights simply because the alternator is not capable of putting that high a load on the engine. If you managed to overload the alternator without blowing a fuse, you will probably end up with a low power situation, eventually followed by a dead alternator.

There are many methods to control idle speed. The ECU on most modern cars will monitor idle speed, and open a circuit that bypasses your throttle in order to keep idle within spec. Idle should not drop noticeably unless a very large load is applied. On a modern motorcycle, idle is usually controlled by a simple throttle stop screw, although the ECU sometimes has control of an enrichment circuit, or the secondary set of throttle valves. On a bike, load may effect idle.

The most important thing to note is that modern car alternators are usually capable of supplying about 80-150 watts, when running at optimal engine RPMs (which is usually WELL above idle speed.) A quick calculation shows that even at peak output, a 40% efficiency a 150 watt alternator will not draw more than half a crank horsepower. That's hardly enough to be noticeable.

For comparison, you might gain a full horsepower by driving in 10 degree cooler weather.

Phew... After writing all that, I'd appreciate some research and thought experiments before responding.