TeamSwift

i read recently about a guy who removed the alternator from his vw bus, installed pv solar panels on the roof and a couple of deep cycle (marine/RV) batteries on-board. The output of the panels and the extra storage capacity of the deep cycle cells kept the sytem working fine, even at night - he drove round trip from texas to seattle on this set up.

how much fuel would it save if an engine didn't have to turn the alternator? depends on how much power the alternator is supplying and the parasitic losses involved. if i had to guess, i'd predict savings between 1 to 5% - but that guess is based on a series of assumptions so unfounded, i'm not even going to bother sharing them here.

other options... (none of these are planned, just thinking out loud)

• leave the alternator attached and the belt on, but add a switch inside the car on the rotor field control wire, effectively giving you control over when the alternator is active (from an efficiency standpoint, it's best "ON" when you're decelerating or descending a grade - the same times regeneration is active in hybrids)
  
• same setup as above, but only use the alterator switch as a back-up for long range trips. for short-range use, re-charge the battery with a charger in the evening. (you can tell your neighbours you've got one of the first plug-in hybrids.) or recharge with solar when you're parked.
  
• even more efficient: take the alternator belt completely off (there are still parasitic losses (bearing/pulley fan) in options 1 & 2). again, recharge when only when necessary via solar/dc charger. downside: less convenient when you need the alternator for long-range trips or "emergency" charging - have to re-install the belt - also this is a bit of a problem for the 1.0 since the water pump and alternator run off the same belt - have to work around that.
  
• buy 2 batteries and charge one (trickle/solar) at home during the day, then swap batteries each evening or as required

just a note: deep-cycle type batteries (RV/marine) would be a necessary part of this approach. a regular automotive battery would be damaged/degraded from a significant discharge.

i also read recently about an alternator/generator which runs off exhaust gasses, turbo style: TIGERS—Turbo-generator Integrated Gas Energy Recovery System.

Yea,thats an old drag race trick to switch off the alternator field circuit.
An alternator conversion book I have says a 50 amp unit takes about
5 hp to run...Our cars have electric fuel pumps and our computers are
programed to say "goodbye!" at 10 volts.Dont know how long we could
run on battery alone.Any other load (lights,blower fan,etc.)would shorten
running time drastically!Perhaps the veedub was carburated,only ignition
was needed(a magneto would require none!),but fuel injection is the only
way to go in fuel economy...

do you mean "goodbye" as in "RIP", or "goodbye" as in "wake me up when you've got 12 volts again"?

surely you can't wreck an ecu just by running out of juice... no, that would be silly. lots of folks kill their batteries when their alternators die and they keep driving.

even if you only saved 1 or 2 hp, it would be worth it. when you consider it only takes 15-20 hp to move a typical car at highway speeds on a level road, freeing up an additional 1 or 2 hp is significant.

I had a friend (an accountant) who was able to find a 2mpg difference in late fall/winter due to the early sunset, and use of lights on his commute. This was in a 87 turbo 3, so I think your idea has merit.
Mount your alternator on the roof with an impeller

impeller. good idea.

i was leaning towards installing some kind of hand crank for the passenger ... to keep down aero drag, of course.

Remind me not to commute with you...

hmm. you might only have to crank some of the time. look what i just found:

"Alterpower": Alterpower is a brand new device that fits in line with your alternator and monitors battery voltage and throttle angle, and then decides when the alternator is really needed, and when it is not.

works off manifold vacuum - disables alternator when map rises above a certain threshold (i.e. under hard acceleration). wouldn't do much for me, since i hardly ever stand on the gas or rev above 3000 rpm, but it's the same sort of idea...

http://www.bestservis.com/digerurunler/ ... er_eng.htm

i have seen some race cars run the alt off the driveline.

Somewhere between thinking of how to go fast and how to get MPGs, I keep look at those useless rear wheels.

My engineering madness tells me this is a good idea. Put two small electric motor/generators on a spindle with each rear wheel. Apply power to the wheels when requested and return power when needed. Works as regnerative braking too. With the torquey charastics of E-motors, it wouldn't take much. Two "5hp" motors will break the tires loose at any point the engine is bogged in 1st or 2nd.

That'd surprise that kid in the Tracel that thinks he's hot stuff.

Jay W
505/287 Dakota

The ECM takes a nap until voltage rises above 10 volts.Superf1y has a
good point as to alternator load..Wonder how much the DRL's pull?How
bout a bigger alt pulley to slow it down?Dont know if our built in IC
regulator would take kindly to being toggled on and off,maybe some
of our electrical engineer types could help us here?Wind driven is a
LOT of drag,I'm in aviation and this is only used for emergency..If
ya attach to wheels or drivetrain,does this not cause drag also?
Just some thought pondering questions......

for a minute i thought you were going to suggest getting rid of one of those useless rear wheels and going for a 3-wheel setup.

a hybrid arrangement would be cool. here's another way to do it that doesn't involve messing with the metro itself ....

some industrious electric car owners have built custom trailers which either (a) carry a generator to charge the batteries while driving (essentially making it a gas/electric hybrid), or (b) have a self-contained internal combustion drivetrain that actually pushes the vehicle.



the 944 is a pure EV. the trailer is a fully functional front half of a front-wheel-drive vw rabbit with an automatic transmission, self-contained with shortened exhaust system & fuel tank. the driver has an extra set of controls in the porsche to start & "drive" the pusher trailer once out on the highway. <a href="http://www.jstraubel.com/EVpusher/EVpusher2.htm">here's his web page describing the set up</a>

i would like to do exactly the opposite:

- make an electric "pusher trailer"
- the trailer would be for sub/urban use only
- with electric-only propulsion up to about 30 mph
- plug-in and/or solar recharging
- added benefit: swappable between multiple IC "host" vehicles



a 48 volt system with a 10 hp electric motor would suffice for a car the size & weight of a metro for low speed driving.

around town, drive it like a prius: gas engine off, pure electric drive up to around 20-30 mph. above that, switch the IC to "on", and pop the clutch to start the motor if you need to go faster. for hwy trips disconnect and leave the trailer at home.

no plans to make this, just like thinking about it.

a hybrid metro to park next to your wife's prius, woodrufj?

my uncle has a prius, and it has an electric motor going into the transmission. so how about an electric motor where the starter is? it would probably need a trans of its self for cranking speed and driving say, 300 and 1500 rpm. and of coarse room for a big electric motor.

I've heard that simply installing a solar panel to assist the alternator has some minor gains for improving fuel economy. There's a number of commercially available PV panels designed to trickle charge your battery through the cigarette plug that can do this. In our vehicles, the lighter plug is on the ACC circuit and is disabled once the car is off. I did run a PV panel for a while in my old Sprint, and found that it actually killed my battery once. Backfeeding power through the ACC circuit with the power off will keep the stereo on, and allow it to continue to draw battery power. The radio does not run on solar! The only real benefit I noticed with this setup was that I could still hear the stereo while the starter was cranking the engine. I never thought to pay attention to fuel economy.


You could actually implement a system where your passenger has a set of bicycle pedals to turn the alternator.



There's actually a number of JDM vehicles that do the RWD hybrid thing exactly as you describe.


Actually it's enough that the American auto manufacturers petitioned the EPA to allow them to disable their DRLs when they're conducting emissions tests for their vehicles. DRLs draw more power than running with just the headlights because the circuit consists of the full headlight load + the DRL resistor which is in series with the headlight ground. You're burning gasoline to heat the air space inside your left fender well.

Let's look at your calculations there -

The only way DRL will pull the full headlight load + the DRL resistor is if they are in parallel.

The purpose of the DRL resistor is to reduce the power output of the headlights, because it has been determined that they are more visible in the day time at reduced brightness (my guess is it's actually the color temperature).

Anyway, I digress, back to the calculation. As we learn in high school, for a series circuit - R(total) = R1 + R2 - and W = V x V/R, so as we add another resistor in series, R must increase, and as R increases W decreases - therefore - the power consumed by the daytime running light system can never exceed that of the headlights themselves - quod erat demonstrandum

Yes, the power not consumed by the headlights is used to heat the air somewhere in the vehicle.

Using W=I^2 * R is easier. And keep in mind I*R=V(constant) The lights are dimmed by limiting the current (I). Limiting the current it done by adding resistance (R). So I^2 goes down a lot faster than R goes up, hence less power consumed.

Yeah, I've seen the RWD electric motor concept on an old Chrysler mini van prototype. But with our mini cars it would take such little power to make a hugh difference. The Metro Hybrid, 60HP@6000RPM, 250ft-lb@1-60mph

Jay W
505/287 Dakota

Mount a pulley on the passenger side drive axle shaft and run a belt and tensioner to the alternator. Just have to find a way to spin the water pump.

Wait.... that won't work. The suspension moves the axle....ah nevermind.

mount the alt to the lower control arm, or put a spring loaded tensioner to take up the slack as the car jounces.

Anyone thought of using a thermocouple to generate electricity from the exhaust heat that is otherwise wasted?

How bout a steam powered generator running off exhaust heat?

Using any of the cars momentum to power an alternator is still going to cause the same amount of drag on the drivetrain to get the required power output, so no matter where you hook an alternator you are still using engine power to spin it. Even if the alternator is stuck on a wheel and the wheel is riding on the ground. Using exhaust or coolant heat to me seems to be something that is otherwise wasted and dumped out of the car but could be used to charge the battery and maybe power some helper motors on the back wheels. With a setup like that the motors would always be driven by any extra power they extract from the exhaust heat. This energy would be put back into making the car go helping to take some of the load off the gasoline engine.

you mean sort of like this BMW steam assist proposal?

sweet!!!

I want one

That beats a thermocouple all to pieces.

i dont think the drag would be the same. i would think it would be much less because of torque multiplication through the trans.

Since we're all going loony - hook it up to an exhaust driven turbine - I'm sure Jess can work something out for you.

Basic electrical math:

Series wiring:


Parallel wiring:


Lets assume all resistor values are 100 Ω. In a series circuit the total resistance would be 300 Ω. In a parallel circuit the total resistance would be 33.33 Ω. Obviously a series circuit presents a higher electrical load. Although I was in error about the headlights getting full power, the entire circuit consumes more power when the DRL resistors are involved.

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Not withstanding the conversion losses, it should be feasible to use a turbocharger to drive an air motor to propel the alternator. Because we're not dumping the compressed air into the engine, we can crank the boost as high as the compressor will efficiently allow. No BOVs will be needed as air flow will never be interupted by a throttle plate. If anybody asks what it is, just tell them it's an electric turbo!

Higher resistance means less current draw, not more. You have to know that.

I think you need to go over that math again - let me make this simple

We're going to use that old high school formula above, since it get's rid of the variables

W=V*V/R - anyone has a problem with this? I'm willing to show how it's derived from the basic formulae V=IR and W=VI.

OK - now let's plug some numbers in

for convenience let's keep V=12, and make R=100 and 200

With a 100 ohm resistor - 12*12/100 = 144/100 = 1.44
With a 200 ohm resistor - 12*12/200 = 144/200 = 0.72

As the resistance of the load increases, the power dissipated in the load will decrease if the voltage is held constant. Anyone else disagree?