Alternatives to the alternator
 

We all know you can't run an SI engine very long without some sort of system for recharging the battery, but not all of us are sure to know all the options available. Therefore, I thought I'd open this thread to gather them all together in one place.

1. MetroMPG linked to the TIGER option. Very cool and sure to see actual production. :thumbup:

2. Then there is the tried and true underdrive pulley. For those not familiar with this option, here's how it works. In round numbers, the pulley on your car's alternator is sized relative to the crankshaft pulley to charge slightly at idle (or perhaps a little above idle), and to produce full rated power by about 1500 engine RPMs. The particulars differ from engine to engine, but that's the general idea.

An underdrive pulley is somewhat larger than the OEM alternator pulley, so slows the rotational speed of the alternator. By slowing the RPMs of the alternator the point at which it begins charging is delayed by several hundred RPMs to as much as a 1000 RPMs or more. That delay removes the alternator's electrical load on the engine at low engine speeds, and hence potentially permits better hypermiling in that same low engine speed range.

As an aside, underdrive pulleys are commonly used on water pumps, as well, and for the same reasons.

3. A somewhat more radical approach, but still very doable, is to move the alternator to a position that turns only when the car is rolling. Here is a photo of a (race) car with the alternator mounted above the transaxle and being driven by means of a conventional 'two pulleys and a belt' setup using a CV joint-mounted drive pulley. Again, sizing the pulleys to start charging at your desired speed is key. Oh, and sorry the photo doesn't show much detail, but I'm confident you get the idea.

http://bringatrailer.com/wp-content/...r_Engine_1.jpg

4. Field circuit switch. Most (but not all) alternators have a so-called 'field circuit' that uses a little juice from the battery to 'excite' the internal circuits of the alternator to make electricity. Without it the alternator will spin, but does not generate any charge. The wire feeding the juice attaches to a terminal on the alternator housing. Identify this wire and then wire in a dash-mounted toggle switch to cut the field whenever you wish.

There are a few options. Surely you guys can come up with some more! :thumbup:

I like Option 4 the best. Here is why:
A) It is the cheapest.
B) Totally reversible
C) Manually controllable so you can turn it off or on as needed or not.

One alternative for spark ignition is the old tried-n-true magneto.

I think that Tiger thing is pretty cool. With one of those, and an electrically driven power steering power steering pump, AC compressor, etc. you could potentially have no loads on the engine other than the drive shaft.

One thing I can surmise is that the alternater takes about 10% off a car's fuel efficiency. There are so many independent sources that claim up to 10% improvement after the conventional alternator is taken off-line. That's good to know. For me, a 10% improvement would be 3-4 mpg.

Tigers sounds great but...
 

That article is dated Sept. 2005, is ther a more current article?
Has an exhaust driven alternator been developed and marketed?

If it really works and is available I would be interested in acquiring
one for my own use. If not, then I can see a potential market
if I had the resources to work on this product.:)

just found this Permanent Magnet Alternators and Water Pumps

interrupt switch 4 engine loads?
 

For those of us out here who are "electrically challenged" ( I know not to stick anything into a wall socket ... except a plug) , would you elaborate a bit on the specifics of this "load switch"? I am in fear of burning up a very expensive alternator. It sounds great to me! The battery gets lots of charge time, anyhow....My Scangauge shows me great numbers of (downhill) "charge times" but who needs alternator drag while pulling a steep grade? -whitevette

I learned that when I was about 10 with a pair of tweezers OUCH they got real hot real fast.

On another note Option #4 the field wire would have to be killed before turning on ignition. Once you excite the alternator you don't need the field correct? Or not. That is what I thought they taught me in Mechanics class in HS.

TIGER sounds cool, but would need to be managed by a computer. Also, anything that resembles a turbo sees heat and requires maintainence <anyone have experience with the old Porche 924 T?)

Unheard -

This looks really cool. If it is compatible with my Saturn + If my alternator or fuel pump fails + If I can afford it, then it may be my replacement option down the line.

CarloSW2

How about this hairbraned idea?

Add a large auxillary battery, a selector circuit, and an alternator disable feature. It could work like this: Charge the aux battery at work and home. Run the car off the aux battery in 'total loss' mode (that is, no charging by the alternator). If you are on a long trip, or if you fogot to plug in your car, or half-dozen other problem come up, the 'smart circuit' senses the low voltage across he aux battery's terminals, and switches over to the OEM alternator/battery. The so-called smart circuit wpuld need to monitor the OEM batteries condition as well, and isolate the two like my old camper did.

A couple downsides include weight and space (aux battery, charger and relay switches), one more thing to break (although I could imagine a simple knife switch bypass).

Add a forklift battery and charger, then coming up with an appropriate relay and 'smart circuit' ? Leave the OEM battery and alternator in place. Charge off the grid, or better, off photovoltaics. Use a large enough aux battery to run the CPU, lights, wipers, radio, etc.

I'm not battery guru or electrics expert, why is this a dumb idea?

i would like some more info on permanent magnet alternators. Are they a good amount more efficient?

metromizer -

It sounds like a good idea to me, as long as the second battery is used according to it's design specification, i.e. don't run it below whatever charge will reduce it's lifespan. I think the forklift batteries are the "marine-style" deep cycle batteries, right?!?!?! If yes, then I think those can be run pretty low. I always like the option of "switch back to stock" running mode. The best of all worlds (at the cost of additional weight).

I think we need a battery guru to make a "battery comparison thread" that describes the types of batteries and their applications/specifications.

Google google google ... Here's a FAQ on deep cycle batteries :

Deep Cycle Battery FAQ

CarloSW2

if you EOC doesn't it switch off the alternator as well? i can "hear" my battery voltage through putting the fans on full-blast and listen to them speed up and slow down with EOC.

Sure Mod, Your unmodified alternator is driven off the engine. If you turn off the engine then the Alternator and the water pump and all the engine accessories stop turning also.

I think a switched alternator and extra battery is a great idea. Just think last time your alternator died, you were probably able to go quite a ways with it not working. Itd be the same thing here. Top off the battery at home or work, and for the short trip that the average person does, youd do just fine, even better with an aux battery.

I really do think some kind of monitoring is best, so you dont get it so low that you wont get the car started if you shut it off, or end up really shortening the life of the battery by draining it way down a lot.

I wonder about even some sort of pulse width circuit one could make for the field coils, like charge for 10 seconds and stay off for 50 seconds, adjustable based on current draw from the battery. (Pulse and glide for your alternator!) Might be able to be done with a 555 timer but Im not real good with electronics. Maybe even too with a relay controller like Siemens Logo or AB Pico, or with a pulse timer controller for dust collectors. Just thinking of things Im familiar with at work.

I wouldnt run the alternator off the trans output shaft. Then if you get stuck in traffic, you might as well call for a tow truck now. Unless you leave your original and put in an extra one that runs off the output shaft, and switch field coils as needed.

I've been watching the amp gauge I installed to get an idea of how much power I would need for my rear battery....

With EOC, My alternator was putting out 50 amps last night during pulses to make up for when I was coasting with it off.... That's quite a draw...

Permanent Magnet Alternators sounds like a non-contradicting-oxymoron :cool:.

If it is an ALTERNATOR it produces ALTERNATING CURRENT, hence the word ALTERNATE.

If the gizmo has Permanent Magnets imbedded in the thang, a generator and it generates DIRECT CURRENT (DC). A generator can also be used as a motor.

Magnetos are great if you are operating a race car, but not very reliable in a street vehicle. Besides to stop the darn engine you must have a grounded kill switch to stop the thang from running. You turn off the key and it will still run. Really, really, safe......not!

Be careful if you have an ammeter. The two posts on the back of the gauge carry the FULL amp load. If is is showing 50 amps and you accidently ground the two post, you get 50 amps :eek: of 12-15 volts DC. IF that happens you may need to change your shorts. And there is a fuse in the ammeter lines ???

I wonder how long a car battery is going to last if a guy or gal keeps farting around with the alternator trying to save a few cents. Get rid of the multiple stereo amps & multiple speakers. You save fuel and your hearing.

but, dude, it is trivial, I mean trivial, to set up a magneto to turn off with the ignition key! Don't play the safety card on that!

The ignition key on a car turns off the electrical power, to stop a magneto it must be grounded. The Magneto is a self-contained system, a DC generator complete with permanent magnets and a distributor. A typical 30's, 40's, 50's INDY 500 car had no battery or electrical system except for the magneto. see http://www.taylorvertex.com/Vertex/p...structions.pdf

cobraBall...

My Amp Meter is not an in-dash pass through. I have a 100 amp shunt and a panel meter to monitor. The Shunt is connected between the alternator and 70amp fuse input to the fuse box.

...Do a search, find the other thread where we were talking about this.
My method, giving up some efficiencies, is to use a deep cycle battery, to an inverter, to a charger to the house battery, and kill the alternator field/ or use a Normally Closed selenoid or relay to disconnect the charge line to the alternator.

The reason for this inverter/charger setup --- mantains proper 13.8 voltage to the car. And 2..... I have yet to find a DC-DC converter that can do 12v-13.8 40amps (not for less than $50 anyway)


.... if you will notice, not many here have large stereos.. THEY WEIGH TOO MUCH!

Not all of us are 16 years old.



[QUOTE=CobraBall;54588]

QUOTE]

a mag on a street car makes your car easy to steal... VERY DANGEROUS :p <reaching a long, long way LOL>

When I was a teen, there were a few street hot-rods running around sparked by a magneto, usually supercharged V8's. I knew one guy who ran a mag, who installed a quick release steering wheel, so he could keep his ride safe from theives.

On a more serious note, can we agree that on balance, the horsepower required to generate that spark is equal?

I mean to say that weather you charge the battery with an alternator and draw energy from it to spark the spark plugs, or generate electricity with a magneto to spark, they both take power, no free electricity.

If so, trading one power draw for a different one doesn't help. Again, good discussion point, though.

A magneto might have been a tiny bit more efficient. Especially if you could get rid of the alternator and battery altogether, like a dragster. But even the fuel delivery on most of our cars needs electricity to work, so...

is there any benifit to be had from P&G'ing the alternator? seems to me that when you switch it back on it will take the same energy charging as if you had left it on all along?

the only benifit of the alternator cut out switch is if you install a deep cycle battery and run the ignition off that right and charge at home? thats when you get the +10% FE right?

There is no advantage to P&Ging an alternator unless you pulse it while braking like BMWs new system (I forget what they called it). If you are already driving for FE, you use the brakes so little already that I don't think this would provide enough charging time. So, you'd still have to have a way to turn it on for normal charging should voltage drop too low.

Noel.

"DC-DC converter"

Convert DC what to DC what?

CB

Can I answer my own question?
 

Last night, I was talking to a EE friend of mine...and the subject of turning off the field of the alternator ( to reduce the charging drag ) came up. His rather quick response was "Don't!" Then he remarked "How many HP in, say, 1300 watts?" I said "Less than 2." He then said " And you're gonna save how many MPG? You can't even measure this." He then said "You'll be sorry, later, when your charging system electrics go sour." He was referring to the pulses in the system when this "switch" was cycled ( off, on, off, on again...). Poor alternator! Poor relays, poor diodes, etc.
So ... I guess I'll leave well enough alone.

What to watt?
 

No, DC what to watts. :D

Uhh... your diodes are CONSTANTLY cycled while the alternator is putting out juice. I don't think your friend thinking correctly if he doesn't think a couple horsepower wouldn't make a noticeable impact on mpg. Given that a beetle takes 12 hp to maintain 55mph, 2 hp is HUGE!!!

Car electronics want and expect around 13.8 vdc.... if you run for say, half hour with no alternator, your going to be dipping into 12.4~ range,,,, this is bad for the battery, and not good for electronics.

A transformer (DC-DC converter) could be used to bump up a deep cycle battery,... as you draw from it... up to a constant 13.8vdc

accomplishing this is possible with items many already have... a 4-600 watt inverter, and a 40amp battery charger.

Get to your location, and charge the deep cycle.

EE think is beyond me, but...
 

Yes, the diodes are constantly cycled...back & forth between battery voltage and alternator voltage(regulated). But slammed between zero and 14+?
I think he used 2 HP as an illustration... to make a point. I know it doesn't take much at all to give my ScanGauge the jitters. Now I'm skeered! I think I'll pass....:confused:

Sorry you got skeered. Lots of good ideas get killed by would be know-it-alls everyday.

i think its a great idea. car electrics should be able to take switching on and off because thats what happens when you turn on and off you car!

the only bad thing might be if you lose the radio code when tinkering.

i know lots about batteries - i have custom built electric bikes.

for this application it is easiest to get cheap deep cycle batteries. however it would be best long term to go for nicd or nimh batterys.

it might be good to leave the normal battery untotched and have a relay system that disconnects alternator and switches to auxillery battery with one button press. then if you mess up you can always switch back to the normal battery.

[QUOTE=CobraBall;54588]Magnetos are great if you are operating a race car, but not very reliable in a street vehicle. Besides to stop the darn engine you must have a grounded kill switch to stop the thang from running. You turn off the key and it will still run. Really, really, safe......not!




They are used universally in light aircraft engines although they usually have two in case of failure.

True and..

"...the vast majority of aircraft with piston engines are using magnetos as their sole ignition source. In spite of over 100 years of experience with magnetos, extensive certifications of aircraft magnetos and quality control requirements by the federal authorities, they still fail or require maintenance, more often than any other part of an aircraft engine. Slick Service Bulletin 2-80 states that 4200 and 6200 series magnetos now being produced should be inspected externally every 100 hrs. and internally every 500 hrs. Parts subject to wear should be replaced as necessary at this time, magneto shaft bearings must be replaced every 1000 hrs." SOURCE: Electronic Ignition for Aircraft :)