Test: Alternator vs. no alternator = 10% MPG gain @ 70 km/h - Page 17 - Fuel Economy, Hypermiling, EcoModding News and Forum

MetroMPG · 01-31-2012, 09:10 AM

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Originally Posted by toc

What if the exhaust pressure was used to spin some sort of fin in the exhaust stream which in turn spins the alternator to produce electricity ?

Nerys · 01-31-2012, 10:13 AM

yes that would work but not to replace the alt maybe to suppliment. turbines need "torque" and your just not getting any torque on such a small turbine at such low pressures. Remember you can snuff these cars out by holding your hand over the pipe (cold of course)

what I am thinking of as they get cheaper is high temp peltiers on the exhaust pipe top extract the heat and make it into electricity.

Ladogaboy · 01-31-2012, 09:58 PM

You might be surprised about the force that could be produced with the turbo, especially if it is specifically designed for the purpose. As it is, the turbine won't back up the exhaust too badly, and with a wastegate, you can control how much pressure is being feed through the turbine.

I agree, though... supplementing with a thermoelectric generator couldn't hurt.

Mr. Previa · 02-05-2012, 08:23 PM

I found these items for up-ing the voltage when running without alty's. Hope it helps some one. I would be all about the DC-DC converter if my budget would allow it. Maybe later.

993 « XS Power - 933 DC-DC Converter

Products « XS Power - 14 volt batteries and chargers.

These are retail prices. I found these products on ebay and Summit Racing for much less.

Tesla · 02-09-2012, 07:22 AM

High all, new here.
Have been reading various threads for the last 2 days, drive a 4x4 wagon, will post about that later, but this thread caught my attention.
I have thought about the alternater issue for a long time, but like all mods and life in general, "you get nothing for nothing".
So just some comments re the discussions so far:
1 / The Seebeck cells, I looked at these a while back for other reasons, they generate current using a heat differential, so you not only need a heat source you also need a cold source, if both sides of the cell are close to the same temp, then no current, therein lies the difficulty. Currently I think the technology is where solar cells were 30-40 years ago, more novelty and specialised applications, give them another 10 years or so and we may have something useable.
2 / Driving alternator off other moving parts, or wind flow will be less efficient than the current belt drive.
3 / Useing exhaust to drive turbine alternator is not free, all turbos bog down the engine to some degree, they create more power because more air and fuel is pushed through the cylinders, if you slow the exhaust down too much either with the alternator idea or by cooling the hot gasses too much, then flow backs up, engine bogs down and FE bottoms out.
4 / Electronics still needs to catch up with the eco/renewable sector to be able to process a large number of variable sources and turn them into a standardised useable form, i.e. 12V, I have run dual battery systems and they call them selves state of the art, but they do not have the ability to unify 2 supplies concurrently like alternator and solar cells for instance, all they can do is switch to the dominant source. So trying to recover odd energy losses from the engine is very difficult because none of them match the required criteria most of the time.
As for the alternator disconnect thing I think it's great for those that do mostly short day trips or just occassional driving and can keep the battery charged with a dashboard solar cell. For the rest of us the first steps would be to minimise electrical draw, primarily lights, by using LED's where possible look, consider relevant design regulations, especially with headlights, just because you can buy them don't mean they are legal. I think appropriate systems can be developed easier on large vehicles than small vehicles, because all vehicles need x amount of lighting as it is dependant on the driver being able to see the road, not engine size, so generally as vehicles get bigger, extra batteries are not a burden, but gains are less as an overall percentage, because the alternator burden is less as an overall drain.
My current thinking is, after doing all the electrical demand reduction mods, to leave std alternator system in place, but set up aux battery system that can be charged by solar and begin shifting all high use items over via a secondary fusebox. So switch over starter, thermo fans, lights, ventilation fans, demisters etc. basically leaving original system just for engine management. This way alternator will hardly ever run, original battery will probably last the life of vehicle & if aux is down, flick a switch and let the alternator kick in.
Lots of talk on deep cycle batteries, just remember they are not suitable for rapid discharge like starter motor, thast type of current draw will kill them quick.
Just my 2 cents worth.

Nerys · 02-09-2012, 12:04 PM

Most of the TEC's need a 100' differential. put a nice HEATSINK on the cool side and have it in the "airstream" and you will EASILY have a bit more than the 100' you need for temp differential.

one side does NOT need to be cold. it just needs to be far enough temp differential. so if one side is 600's and the other side is 400's you have your differential and your making amps.

though they are rather expensive.

There is pretty much no "real" dot regulations for non visible bulbs. IE tail lights turn signals etc..

for headlights YES dot regs are a minor issue. I don't really care about dot regs as far as "lawbreaking" goes but I DO care about them as far as keeping ME and other drivers safe.

SO when I figure out how to go LED headlights I plan on jump through the DOT regs as needed to make it right.

A deep cycle battery TODAY has more CCA than a STARTER battery from years past. especially NICE Deeps like Optima's

my optima marine blue top deep cycle starts my car better than the "regular" starter battery I removed from it.

but remember I am driving a 3cyl metro. a lawn tractor battery is good enough for this. a gel cel from a emergency light is good enough for this (yes tried and tested)

these cars just don't consume all that much power. I think I totaled my power consumption at 10 to 30 amps depending on lights on or off

Just changing out all the little bulbs to LED should get me closer to 20amps lights on. 15 if I can figure out how to go "LED" for the headlights.

ie all led with 2 decent deep cycles (twice the CCA BTW) and I could go a week between "charges" without going below 50% SOC on the batts

add a solar charger and in the summer I won't even have to plug it in at all to recharge as long as I park in the sun.

I DO plan to look into isolating one battery when "engine off" so if I good and leave something on I have one full battery at least :-)

oil pan 4 · 02-09-2012, 02:17 PM

I need the best of all worlds.
Light weight high power LiFePO4 batteries, with 13.2v, slightly more cranking amps than the stock starting batt setup and a lot more cranking amps compared to deep cycle batteries. I am turning a 395 cubic inch, 22:1 compression engine over.
I am building serries a 21ocv 6 amp solar panel to recharge during the day.
With a good size solar panel I plan to not need external power at all, summer or winter for normal driving around town. I will reinstall the alt belt for longer trips.
Going to install an alternator cut out switch and rig up a quick removal belt system after I get the P/S driven off its own belt.

Nerys · 02-09-2012, 02:35 PM

how much surface area do you have for panels? you only get full power in direct perpendicular arrays. impossible in the winter up north maybe not so hard in new mexico?

if your panel is big enough you might not even need it for long drives. how are you handling charging that battery? what charge controller you using?

what battery pack capacity and price are you looking at? always interested in new cheap sources of lifepo4 goodness.

do you know what the "draw" is of your car management system. I think the metro is only 7 amps or so ie a slightly larger panel might get you real time power capacity!

what I would love to do is mount an AC clutch pulley to the alternator so it "free wheels" and automate it such that when the power is too low the clutch is triggered and bingo you have alternator power again.

oil pan 4 · 02-09-2012, 03:15 PM

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