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

[modmonster]

this is a sweet thread!

aren't the alternator leads really thick? how are you going to have a remote switch for that -the amps will melt it?

a diesel would be best for this purpose then you don't have electrical ignition to worry about! once a diesel is started you can disconnect the battery completly and still drive it.

how much juice does it take to keep the spark plugs sparking on a petrol engine? isn't the alternator controlled in some way or is it always running?

[MetroMPG]

The lead is fairly thick - not sure what gauge (less than 1/4 inch dia.), but I cut it easily with a pair of needle nose pliers.

As for switch selection, there are all kinds of sizes available to handle the rated current. Check the link BBsGarage posted for examples. (I'm not planning a remote switch - it'll simply be in line under the hood.)

Good point about the diesel not needing power for ignition, but it still needs power for the ECU. And what about fuel pumps - are all diesel pumps mechanically driven?

[Roman]

Heey i found your topic

And me as a crazy one liter driver also thinking about an alternative.

I've got some idea's:

1) Stirling engine
2) Solar
3) Seebeck-effect
4) Some guy on a dutch forum said to change the coolliquid whit ethanol (boiling point 80C ) and power a steam engine whit it. Or just raise the pressure of the coolwater to about 1.5-2 bar will also down the boilingpoint...

But we have some 80-90 degrees hot water in the car. So i think we can do something whit that.

Or make a combined constuction.

What i was wondering, you said that u just diconected the cable and not removed the alternator. Will this also give improvement? When yes would it be possible to keep the alternator and just putt some more energy in to the circuit from outside (like with solar pannels)

We could also remove some lights (like breaking light, daylight etc) and replace it whit a Led construction. Going from 15-30 watts to 1.

I will try to get/make a small Stiling engine who can run a default alternator.

And would a new alternator be an improvement. Like mine is from 1992 (thats 16 year old).

[Newton]

Seems to me that the battery replacement isn't really that much of an issue. Lead acid batteries may not have many cycles but partial discharges only count for a partial cycle and for the majority of my trips it would only be a partial discharge. Then when I get home I could just plug it in with a trickle charger under the hood. I've heard of electric cars that have lead acid battery packs that will last about 3 years before needing replacing. With a 10% increase in fuel economy I believe that within the lifetime of the batteries they would pay for themselves. Taking my vehicle as an example it would yield a 5.5mpg increase and if my figuring is correct using my specific cars specs and track record I would save $14.73 per month, $176.80 per year, and $530.41 every three years if gas stayed at $3.60/gallon (cheapest it's been here in a while besides now). So unless I waste money on meaty Trojans it seems that two batteries would pay off.

[kane66]

MetroMPG; about your question about diesel needing an alternator.... No is the short awnser. In reality with how a diesel engine works it never needs any source of electricity once it's going.

But the long answer is that unless your car was built before 1998 it probably will need a alternator. Most diesels before then were Mechanical injection and the only electrical part running to the engine is a fuel cut off solenoid, and glow plugs (neither of which are needed). I had my alternator belt break once and drove around for a week on what was left of the charge until I finally had to "bump stat it" to get it going. Most cars after that have a hybrid mechanical/electric pump that is ecm controlled. Great for starting and "noise control" but a pain in the ass in the long run. I personally will stick with mechanical injection until I cant get parts any more.

[RacerX]

Newton, It's working well for me and I have a 140 mile round trip and the return trip is at night. I'm running a pair of group 24 deep cycle interstate batterys hooked in parallel. I plug the car in when I get home and when I get to work. I haven't turned the Atl. on for about 2 months. Good Luck

[MetroMPG]

Originally Posted by Roman

What i was wondering, you said that u just diconected the cable and not removed the alternator. Will this also give improvement?

Answer is "yes". Removing the alternator completely will give the greatest results, but the difference (of belt & bearing losses) is likely small. Probably not worth the hassle.

When yes would it be possible to keep the alternator and just putt some more energy in to the circuit from outside (like with solar pannels)

Sure. But solar is expensive, and you'd be hard pressed to find enough surface area on a 1L car to generate the power needed, even @ peak daylight times.

We could also remove some lights (like breaking light, daylight etc) and replace it whit a Led construction. Going from 15-30 watts to 1.

No harm in doing that. Again, the fuel savings will be very small.

[Newton]

you could produce electricity using the engine's heat by utilizing peltier plates. VirtualVillage.com i've got two 12v 400w plates on the way, i just have to find a spot that gets warm but doesn't exceed the plates max temp and mount them with some thermal grease somehow and put a heatsink/fan on the otherside to cool down the cold side. Not only does using the engine's wasted heat to produce it's electricity increase the overall efficiency of the engine but could possibly completely replace the alternator. Just gotta make sure to put a diode in the line so that when the temperature gradient is gone they don't become heat pumps.

[NeilBlanchard]

Hi,

I thought I saw a thread here on EM that had a turbo-powered alternator?

[Newton]

it'd be tricky to connect a shaft to the turbo blades and would need gearing for sure but it would probably work. seems like it would be taking energy from the engine though seeing as how the energy is coming from the upward motion of the pistons (the exhaust just being the medium like hydraulic fluid) which is just energy from another combustion cycle.