Alternator v. no alternator - 10% gain @ 70 km/h - Page 18 - Fuelly Forums

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Old 05-26-2007, 08:36 AM   #171
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Very interesting reading. I think the best approach might be a combined power system with an intelligent controller. Here's my take on it, from easiest to accomplish to hardest.

On just removing power from the alternator, GM trucks after about 2006 have this function. when the computer detects battery voltage below a certain level, it will turn the alternator on, and when it detects voltage above a certain level, the alternator windings are no longer energized. When the alternator is not energized it uses the same energy as a simple pulley, ie not enough to measure. I doubt it would be hard for an electronics guy to build a circuit board that could monitor batt voltage and turn the alternator on and off when specified. You could even use a graduated approach, ie when the battery is at 13V the alternator is activated any time a high vacuum condition is detected or the brake pedal is pushed, and if voltage drops below 12.5 the alternator comes on period. This could even turn into a nice little business for someone if they made it a plug and play device in a nice little box with a predone wiring harness.

If you have a regular distributor, you could try replacing it with a magneto. Magnetos are used in drag racers that have no electrical system at all. Once a magneto starts spinning it generates enough power to fire the spark plugs. You have to short the magneto out in order to kill the engine. This would eliminate a big drain and would assure that no matter what, the ignition would have full voltage to fire the plugs. The hard part of this is actually finding one, while they were used a lot in the 1920s they are usually only used on drag racers with big block V8s these days. It'll be hard to find one to fit what most of you here have.

A fiberglass hood could easily be modified to accept individual solar cells, so you could line the whole hood with them with no effect to wind resistance. Flush mount them in with a means to replace bad cells when necessary (mounting system to pull from the underside) without having to rebuild the hood each time a cell goes bad. The lighter hood would also help compensate for the added weight of the solar cells and control system hardware needed to allow them to charge properly. No need to restrict this to the hood either, some creative metalwork would allow you to do the same to the roof and trunk lid depending on the vehicle. Just remember that the roof is designed to keep you from being crushed in a rollover accident, so you may want to give this a miss. With some of the new flexible organic film modules, might just have to glue it to the hood and roof with no extra work depending on how thick they actually are. While on the subject of solar cells, the early 90s Mazda 929 used a sunroof with a solar cell made into the sunroof's trim. The solar cell's job was to power a fan that drew air out of the car on a hot sunny day to keep the interior from getting skillet hot.

The turbocharger runs as high as 80,000RPM, so you'd have to have a gear reduction method to keep from throwing alternator bearings all over the place. Nice thing is, it will take very little power from the turbo running, say, 50,000RPM to spin the alternator at 6000RPM. An alternator pulley is about 1/3 the diameter of the crank pulley on a Chevy small block, which means that the alternator will spin anywhere from 3000 to 18000RPM depending on engine speed. And, the turbo doesn't have to be an either-or affair either, a shaft could be installed like a PTO on a tractor to power the alternator. This means the exhaust restriction could be used to both supply more power to the engine and drive the alternator. The PTO arrangement would need to be well balanced, and the turbo would need to be placed so that it can effectively use the exhaust and drive the alternator. The alternator drive shaft would also need to be about 2ft long to keep the turbo heat from cooking the alternator. This would be pretty complicated to set up properly. The easiest way to step down the speed would be a small pulley on the turbo shaft with a belt, and a large alt pulley. The shaft would need to be positively supported on the alternator side to prevent sideloads from reaching the turbo as even a small sideload would be enough to throw the turbo out of balance and destroy itself.

On the question of where a turbo has to be placed, STS makes a system that installs the turbo at the rear of the car. Turbo lag is no different than if the turbo were mounted at the exhaust, but the turbo does run 500 degrees cooler. Here's a Popular Hot Rodding article on this.

No idea if anyone would want to look into this, but Smokey Yunick, one of Chevrolet's greatest innovators, had a device to spin the alternator on his race cars. It was a simple propeller on the alternator mounted under the hood to the front of the car. It allowed him to have full power at speed while eliminating the alternator drain on the engine. It was effective enough that competing teams cried foul and the racing authority of the time ruled it to be a cheat. Course, this was on circle track racing with speeds well over 100MPH, but then with modern methods and materials someone might be able to make one that is effective at 50MPH. One could install a windmill bladeset that dipped into the airflow under the car or in front of the radiator, with a fan belt from the blades to the alternator depending on what kind of room you have to work with. This would be as free as you are going to get if you want to have an alternator working full time. If you did it in front of the radiator and behind the grill, there won't be any additional wind resistance. Course, the alt won't work at low/no speed either.
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Old 07-25-2007, 07:08 AM   #172
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Very interesting stuff guys. I think if I had the money I'd go with making the hood into a solar cell, so probably 3'x3' and obviously not enough to continously go alternatorless, but for a small commute and parked in a sunny parking lot all day, it'd help a bit.

But then I think I'd add a bunch of the peltier chargers on the exhaust header/manifold as my primary electrical source, if I can get 55W out of them for any driving and regarging help from the solar panel when stopped and sunny it seems it'd be the best supplement, you get some charging with the car off (from the panels) and get charging at night if you're driving from the peltiers.

Now I just need $500+ to put in my $300 beater .
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Old 07-25-2007, 08:54 AM   #173
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I never realized Peltier modules could be used in reverse like that. So the question is, how much power does a typical EFI motor require to sustain it's own operation?
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Old 07-25-2007, 03:04 PM   #174
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spark and ecu/sensors, radio, wipers, lights, signals, electric fans, fuel pump, I know I'm missing some.
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Old 08-01-2007, 09:56 AM   #175
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Update: re-belted the alt for the first time since winter (needed full lights for night driving, plus I was on a schedule and didn't want to play amp hour roulette).

Noticed that when DWL, it is much more difficult to do fine tuning with the throttle with the alternator connected. I was seeing jumps of 8-10 mpg with the slightest throttle movement (@ 40 mph/relatively flat roads). With the alt unbelted, I have much finer control over instant MPG.

Not sure what that is.
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Old 08-29-2007, 07:43 PM   #176
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MetroMPG, when you are substituting joules of energy that come through the grid (the ones from the sky are freebies) for joules of energy that come from PetroCanada or its ilk, I think in the long they should also be counted. Add what current you use, some multiplier based on the efficiency on type and time of generation to get the raw joules from based sources and then aggregate that and see how many are required per KM. The per 100 KM metric seems whacky but MPG means that some people think that every additional MPG is just as beneficial as the last. I read your posts and have a ScanGauge based on a few opinions including yours that I found just before going away on vacation and wanted better fuel economy. Anyway, you're well aware of the declining returns and the massive extra efforts that have to go into eeking out any marginal savings.

Maybe if there was a joules/km (any of you in the physics field or high school graduates please advising my of any simpler measure when factored to the km). Then it can be compared to biking, walking, maybe even public transit.

That said, MPG are much more fun to use when coasting and LPH is a better measure on the pulse! ;-)
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Old 08-30-2007, 08:22 AM   #177
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Hi 2Ton - moved your post here where it's more in context...

Agreed that the most honest approach is to factor in all energy used.

In the summer it's predominantly solar assisted, in other seasons, it's mostly from the grid.

It opens a can of worms though...

- What if the grid power is 100% renewable sources? Do we count that, or is it a freebie like solar (the solar is actually more expensive per unit energy at this point, since the panels are relatively new purchases).

- Are we factoring in energy drawn from the grid, or energy consumed in the car? (they're different, due to charging inefficiencies)

- Should people who use block heaters also factor that energy use in their fuel consumption?
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Old 08-30-2007, 09:13 AM   #178
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Hrmm, of course these are all highly debatable except solar which is always free (unless you want tio factor in energy used to make things - turns out nothing is durable in life). ;-)

If people wanted to do this I'd actually say that grid power is grid power (power can be moved all over and everything is connected as we found out 4 years ago) and you factor in some standard multiplier to the energy consumed (for battery charging, whether power pack or a deep cycle, block heating etc.) to recognize the transmission losses and some average generator inefficiency factor for fossil generation (we don't get to choose where we attach to the grid). The tough part is the time of day. Peak power is worth many many more times than 3am power but that's hard to do. Maybe just try and adopt some understanding that using grid power during prime time to help cut emissions and consumption comes up a bit short of the big picture.

The big thing that would interest me though is the energy/km number for comparing to alternate modes like biking which is cheap for short distances but much pricier for long trips when you realize just how much energy your body needs to keep chugging along at 100 watts or more for many many hours in a row, with very regular feedings of expensive high energy foods. I swear that motorcycling was cheaper... ;-)
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Old 08-30-2007, 10:02 AM   #179
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2TonJellyBean,

If we're measuring energy/Km - should we also include the energy to transport, refine, transport again etc. fuel used? There's another thread on the energy cost of gasoline - other than the fuel itself. Once this has been added in, most of the aforementioned forms of transportation are extremely viable.

Don't forget, along with the extra food energy needed for human powered transportation - there's an immeasurable benefit of health. But yes, I can see diminishing returns if you should have to travel 100+ miles in a day.
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Old 08-30-2007, 10:12 AM   #180
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Quote:
Originally Posted by 2TonJellyBean View Post
The big thing that would interest me though is the energy/km number for comparing to alternate modes like biking which is cheap for short distances but much pricier for long trips when you realize just how much energy your body needs to keep chugging along at 100 watts or more for many many hours in a row, with very regular feedings of expensive high energy foods. I swear that motorcycling was cheaper... ;-)
Biking depends on your bike and diet. If you eat nothing but potatoes, cheap cereal, cheap hot dogs, etc... at ~$1/1kWh, it'll cost you ~2 cents/mile in food alone on a normal bike. I know I spend more on food than that, so for me it's likely ~4-6cents/mile. Something like a velomobile can quarter that if you keep the same ~15mph average. A DIY electric bicycle or velomobile is hands down the cheapest form of transportation, at less than a cent per mile. Even w/ the high cost of food, iono about motorcycles being cheaper than human powered bikes. Even if a 250 at 100mpg is 3 cents/mile on fuel alone, the cost to maintain it of another cent/mile, and purchase it of ?cents/mile really push up the cost compared to a bike. A new $3000 bike would need to last ~200k miles with nothing done to it to have it equal the cost of an ordinary pedal bike.

Course, a motorcycle is much faster than a bike outside of the city, so it really comes down to preference and circumstances. But, that being said, ain't much cheaper than a DIY electric velomobile, aka low slung faired electric motorcycle.
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