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Old 01-03-2008, 06:50 AM   #1
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Direct Drive Alternator

Not sure if this should go in this forum or FE, but here goes.

I have looked at all the alternative alternators, and wonder why this one hasn't been tried: a direct-drive alternator.

Things I've rejected: solar array (expensive and not efficient), fuse disconnect (not good at speed or distance), belt removal (must stop vehicle, dirty, etc.), propellor driven (not good at low speed or low airflow - think grill blocks), peltier replacement (not efficient enough, weight), and a few others.

Here's the basic concept: 1) Make sure to have a gearing system that will run the alternator in the correct direction, 2) basically this runs off the crank just like a regular alternator, but will be able to be pulled away to turn it off. Instead of the metal pulleys, rubber-coated wheel on the outside of the alternator pulley, crank pulley would have a rubber-coated area on it for contact as well. 3) Likely using a different than factory alternator as the vehicle (going to be a CRX) will be using LEDs, everything I can do to keep electrical usage down, etc. so I will try to use a smaller (and thus lighter) alternator to save weight, which may be offset by the engaging mechanism. Overall, the concept should result in FE increases.

When alternator power is needed (and it is from time to time) - a mechanical switch can be actuated (likely a cable) which will pivot the alternator down such that its rubber-coated pulley (think how thin serpentine belts are - wouldn't have to be TOO thick) contacts the drive surface on the crank. Must have a method of coating replacement. (Extra tight teeny belt forced over pulley?)

The way in which riding mowers engage the blade is a similar type of system with a belt or two - but same basic concept - get rid of the drag of the alternator when it's not needed.

Similarly, this COULD be used for the air conditioner clutch pulley as well I am thinking - may have a secondary drive to effect either of these (yes, some of us DO want to use an A/C during the year - think a drive through Texas or California, etc. and we just don't want to roll the windows down when it's 110 degrees out. FE and heavy sweat don't mix well for some of us.

I realize I will likely be relocating the alternator in order to make this work, but it seems pretty doable.

Direct drive and/or additional belt linkage like on a lawnmower could really help this out I think. Am I off base here? Suggestions?

I look forward to your comments.
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Old 01-03-2008, 07:23 AM   #2
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Most motorcycles have direct drive alternators mounted on the crankshaft. I'd love to add a Harley Davidson alternator to a car, and only energize the field coils when stepping on the brakes. This would regenerate power like a hybrid.

You'd need to use a deep cycle battery instraed of a starter battery, which is not a problem. But the alternator would have to have BIG output, maybe 200 amps to charge the battery quickly enough when braking. Motorcycle alternators top out at about 30 amps.
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Old 01-03-2008, 07:36 AM   #3
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I see this one on here a lot. If you aren't using much of any electricity because of LEDs and such the alternator won't have much effect on the engine either. It takes electrical load to create an engine load with an alternator.

If you want FE savings there are a lot of other things you could be doing. There are two pumps running constantly on our cars that take a lot of power to run. The power steering pump and the water pump. The water pump is the biggest culprit when cruising down the freeway or straight in town. There is a reason people reduce trap time by disconnecting their water pump.

You want significant savings? Take out your mechanical water pump and thermostat. Put a temperature sensor where the thermostat goes and setup a digital controller that runs an electric water pump. Have the controller keep the pump completely off (kinda daring) or extremely low until the engine is up to operating temp. Then have it either variable speed or just multi-speed. This not only frees up all of the power lost from pumping WAY more water than is really needed through the engine for someone that's not constantly driving the car hard but will allow the engine to heat up significantly faster in the winter.

As far as energizing the field coils only when braking or maybe even coasting. You could do that on the alternator in our cars as it is. Just get fancy with the regulator and/or connection from the regulator to the generator and you'll be good to go.
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Old 01-03-2008, 08:14 AM   #4
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H/D Alternator on CRX

Okay - this is great - apparently I am on the right track!

I would definitely use a deep-cycle battery in order to not foul up the starter battery - should have put that in the initial post.

I don't want to do regen braking. Honestly I think that every time there is a significant advance in ICE efficiency, the automakers go and screw it up with something else. Additional safety measures (think mandatory seatbelts which suck in 2nd gen CRXes, more weight instead of just actually buckling up!), more additional safety measures like a bazillion airbags because people can't drive properly, bigger engines (look at what Honda did), all trying to sell something that people just waste rather than keeping an ultra-efficient vehicle for its own sake.

So - first idea - use a direct-drive alternator off a motorcycle. Does Honda make any of these? I'd stick with a Honda product if I could.

The CRX in 1984 used a 55 amp alternator, by 1987 it was using a 60 amp which continued through the end of its lifetime in 1991. I'm trying to figure out how low I can cut the alternator - and if a 30 amp is the highest I can go, wonder if that is high enough for the system total.
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Old 01-03-2008, 08:31 AM   #5
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@dkjones:

I am definitely trying to avoid electrical usage - otherwise I'd be obtaining an Insight and modifying the heck out of it.

I QUITE appreciate the comments, not trying to shoot you down but let you know what I am going for, why, and I REALLY do appreciate your input, as you sound like you have some great things to say on this subject and may hae more down the road.

Here are real-world issues with electrical P/S pumps. My wife's car is a 2004 Malibu Maxx LT, and it gets insane mileage vs. any SUV on the road. It's got an electrical power steering pump. It saves about 1/2 MPG according to all the Chevy forums, Chevy info, etc. Not worth it due to the one thing that it does oh so wrong - and that is lock up and steer you in the exact direction that it locks up in. As in a problem crash - you start to steer, you're halfway there, you need to change course - and it locks up on you. The major safety feature override on the Maxx. With the '07 they switched back to a mechanical P/S pump. So I wouldn't want to chance that. Besides, enough CRXes come without power steering and it's so light that it's not that bad on a CRX. So my modified CRX - no power steering, either stock or removed.

Now the engine block is something that I REALLY don't want to mess up, and here's why. I plan on grill blocks, figuring out exactly how much air to give the engine to keep it running at its best without blowing it. (May require enlarging engine & radiator blocks in summer.) This vehicle will be used mostly for long trips for business. Figure in excess of 50,000 miles a year, I've put as many as 100,000 miles on a vehicle in a year.

If I've got an electric fuel pump, this will make the vehicle much more of an around-town vehicle rather than the long trips I put in for business. My location makes flying extremely expensive, much more cost-effective to own and drive forever rather than fly. Yes, I can do business along the way rather than only in major cities.

I DO drive at night though so I need to keep the minimum amount of alternator and maximixe electrical efficiency with lighting. I know - extra convoluted but hopefully it will pan out in the end.
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Old 01-03-2008, 09:01 AM   #6
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Only problem is friction drive of the alternator is probably more lossy than a belt drive and in cold or and wet weather even harder to keep friction up enough to make it work. I have a scooter that uses an aluminum sand and epoxy coated drive roller on the motor that rubs on the rear tire to drive it and it is wearing the tire out and has problems in the rain and is rather lossy. It only puts out a peak of 1hp maybe!

Better to put some magnets on the flywheel and then some coils and a switching regulator / charger then take it a step further and make it a motor generator and you have your hybrid.

The better choice would be a high voltage NiMh battery pack and a regulator with an output of 12 volts to run the car and then recharge off the grid. NiMh have more cycle life than lead and are lighter. I have a 50 volt pack (40 F cells) of 15amp hours and a buck regulator that I used to jump start a VW Beetle - it only took about 60 amps to start the VW. I probably could have cranked the engine for half an hour on a battery pack that I carry in one hand.
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Old 01-03-2008, 09:15 AM   #7
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JanGeo - not looking for a hybrid. If it's not possible I can explore both smaller alternators with belt drive and other methods like propeller, but not looking for a hybrid. I do believe 100 MPG is possible with ICE, proper driving methods, removing unused, unneeded and wasted items.

I DO understand that there is an extremely small contact patch with direct-drive alternator vs. belt. That makes an huge amount of sense with regard to losses, friction, etc.

I do wonder if the Insight motor would work in a significantly lightened CRX, use the electrical motor instead of the alternator and get rid of that really heavy battery pack that the Insight has. Basically recraft chassis and body, doors, hood, etc. on the CRX, keep it down to about 1200 pounds. Aluminum seat frames, etc.

This driver is 6'3" and in excess of 200 pounds, btw so I add significantly over the curb weight.
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Old 01-03-2008, 09:25 AM   #8
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If you want better efficiency than a belt, use a chain drive; chains are ~98% efficient when properly lubricated and can transmit more torque as well. However, they are noisier, and a chain would require fresh lubricant every few hours. Even if you forgot about it, it'd still be ~75% efficient.

For selective use of the alternator, incorporate an A/C compressor clutch.

There are lots of different chains available from McMaster-Carr, but given the torque requirements, a bicycle chain and sprockets/chainwheels should be sufficient. A strong tandem team makes as much torque as a small-block Chevy, albeit at a much lower rotational speed.
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Old 01-03-2008, 10:39 AM   #9
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I think your thinking of electric power steering. Not an electric power steering pump. An electric power steering pump used on a conventional power steering rack changes nothing but how the pump is driven. Even on a normal power steering setup if you remove or lose the power steering pump you can still manually steer the vehicle. It's just not power assisted.
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Old 01-03-2008, 10:56 AM   #10
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DKJones - thanks for catching that. Yes - it's electric power steering on the Maxx which translates to if the power steering goes out - so does the FULL steering. I have to massively stay away from that. Safety issue. I will likely strip off the power steering on the CRX I find if it comes with it, be happy with no power steering. Not worth it for 1/2 MPG savings in my estimation - safety first on that. (And I'm trying to get a CRX - how funny is that?)

Several have suggested no power brakes under 2000 pounds - likely what I will go with on the CRX final setup as well. Mechanical water pump - possibly change out the pulleys for less water movement (slower) - would that at least help? Maybe a couple percent?

DEFINITELY like your opinion on that one (and anyone else).

I do like these forums for the best attitudes out there - people aren't flaming but willing to help any way they can. I do appreciate all the comments.

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Originally Posted by dkjones96 View Post
I think your thinking of electric power steering. Not an electric power steering pump. An electric power steering pump used on a conventional power steering rack changes nothing but how the pump is driven. Even on a normal power steering setup if you remove or lose the power steering pump you can still manually steer the vehicle. It's just not power assisted.
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