Test: Alternator vs. no alternator = 10% MPG gain @ 70 km/h

[gone-ot]

...one can "get-a-clue" as to how much current things draw by looking at the sizes of the respective fuses, which are typically (but certainly not always) sized to trip at about 150%, or 50% over normal current levels.

[moonmonkey]

can you open and close the feild circuit "on the fly" without damaging the alternator? what about a switch mounted on the throttle that closes the feild circuit when you are coasting, or is that the wrong time to hit a charge cycle. id like to make it automatic instead of adding another thing to do while driving,,,(i dont think i can make it to work 55miles) in the summer with a/c,, without any charging, and in fl 100+% humidity and 95+ temps i will have to run a/c,, dont want to smell on arrival. might have to go with an underdrive pully if all else fails.

[Bajascoob]

I have this setup on my race truck. not for efficiency but for simplicity of wiring because it doesn't a standard wiring config. It's one of the switches I turn on in start sequence, I have forgotten to turn it on, then turned it on while driving, with no obvious malfunction. Chevy delco style.

[Bajascoob]

The charge light/check engine light may come on when you de-energize the field. That is what mine does..I wired in a biggish light for the race car, acts more as a belt-off light.

[TimG]

There was some interest back in the mid-seventies about putting the parasitic losses of
alternator, water pump, power steering pump, and A/C on "bottom cycle" power. They
experimented with a Rankine cycle using freon as the working fluid, kind of running an A/C compressor as a motor:

ht tp://tinyurl.com/yzomksc

I think it went away with the memory of waiting in lines to buy gas. The peltier, being
solid-state, would be a cleaner, more reliable solution. Making them even larger than the
University experiment would allow adding DC motors to run the other parasitics besides just replacing the alternator.

One thing that hasn't been addressed (in this thread anyway) is replacing the alternator with a more efficient unit. Stock ones are only about 50%, emphasis is on reliability and
inexpensive manufacturing instead. There is a design called an axial flux alternator that has been developed primarily for windpower generation but would be easily adapted to automotive (actually has been for the military). It uses Permanent rare earth Magnets to provide the field, arranged on the inside of two steel discs. The stator is merely copper wire coils (aircore) potted in epoxy between the (field) rotor discs. Peak efficiencies as high as 95% are obtained with careful design and construction by home builders. You can't control output by switching the field, but you can turn phases (coils) on and off. With RPM varying approx 1:8 between idle and top speed but electrical demand varying by much less, something like a unit with six coil phases would match capacity to demand very closely. Using Pulse Width Modulation on one coil while switching the others would be even finer control.

Another loss is the rectification method. Diode banks in standard alternators are set in big heat sinks for a reason- they have about a 2V drop across them, so about 1/8 of the power you generate is lost to heat right there. FET transistors are now cheap so that a switching circuit to convert the AC to DC would be fairly simple and inexpensive to make. Cut that loss down to a fraction of a volt.

[busypaws]

I've had the field wire on my 94 Toyota PU for 10 years now. I turn it on when DFCO, down hill etc. Turn it off on acceleration, up hill, etc.
Biggest problem is training my wife (3-4 time a year she drives it) to turn the switch on and leave it on. Finally took a sharpie and wrote on the dash "Switch Up"
I also go through batteries. 18-24 months is all I get doing this. But buy 3 year batteries and you get a new one basically free. I should probably get a deep cycle / yellow/blue top sometime.

[Nerys]

Peltiers may not be efficient but we have a lot of surface area too. In conversion of heat to watts does out engines "output" enough heave via the exhaust to power enough peltiers to give us the power we need to run the car ? ie replace the alternator 55 amps

To compensate for loads you just need a larger battery. This will "run" everything till the car gets to operating temps and can power the pelts and then they can power the car and recharge the batteries.

Combine that with a solar roof and LED conversion and I wonder if we can do it.

anyone have suggestions on affordable but usable pelts? how many to reliably get say 20 amps of power? (that should be enough when you use the battery as the stabilizer)

[leftlink]

a question: what is the efficiency of a solar panel when used inside of a car? eventually putting it on top is best but just for testing i don't want to have to deal with that right now... drag, drilling in my roof, potential theft, etc.

for example I could put a kyocera panel: sunelec.com/?main_page=product_info&products_id=28 --- 54 watt, 17 volts, 2 foot square size, right below the back window. I don't use my car much but I would bet that this is enough to keep the car charged after the alternator is disconnected.

any one have an idea of this? with untinted rear window or a window offering minimal u/v blocking?

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[busypaws]

My 15Watt one on my truck is NOT powerfull enough to allow me to keep the field on alternator off all of the time. Maybe 54 watts will be enough. I live in Tucson AZ so we have sun 360 days a year. I've found that knowing where to park and setting the angle of the panel to get the most sun helps the most.
I thought my windshield might affect it as well. So I would put the panel on the roof when parked for a few weeks. I did not notice a difference so now I just leave it on the dash.
I think the trick is to get a couple of deep discharge batteries. I leave the truck at the airport for 3 days. Get home on Friday night. I can not make it home (20 miles with lights) on the full charge of the standard battery. To make it work you have to have enough power to make your longest trip without an alternator. I also think you should carry a battery charger with you. That way if you run low you can stop somewhere and plug in the battery charge for a 1/2hour or longer so you can make it home.
Good luck ----- keep us informed on you progress.

[leftlink]

Interesting info. the window on the back of my hyundai elantra says it is "70% transparent glass" so maybe I would still get more than half the power output.

FYI I picked up my car yesterday. It is a 2004 and all I have done is change the spark plugs so far. I just made my first round trip, mostly back roads, and the mileage was 27.5.

Of course, most of the bad mileage was in the first 3 miles with a cold engine, it is about 40 degrees F, so I got another idea... to include a heating element in the solar circuit to warm the engine.

So that if battery is at full voltage and the sun is present, the heating element would go on. Maybe it would only warm it 20 degrees but an engine works much better at 50 degrees than it does at 30.

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