Alternator modifications

[JethroBodine]

In the paper you listed, they showed a 4%increase in efficiency(at 14vdc output) by using a constant 4amp field excitation voltage. They did not generate the excitation voltage from the alternator, but from a seperate power source

A DC power supply was used to energise the field windings with 4A.

. How much power does it take to generate a constant 4amps? The standard alternator set up in their test used up to 50 watts of its own output(variable draw). If it were 50watts, just to make things equal between the two modes, wouldn't that draw a higher percentage of the alternators output at lower engine speeds and/or alternator outputs?

[Arragonis]

Why not just downsize ?

This may have already been covered or maybe is irrelevant so apologies in advance, I work in IT so I haven't followed the discussion on papers, watts etc.

I notice on my new "ride" (1 Litre, 3 cyl Petrol) that the battery is, well, tiny. I mean really tiny. I have an old style MGB which was designed with 2x 6 volt batteries of which I have 2 new ones, but the one in my new car is about the same size, if not smaller, than one of those.

Assume my Aygo also has a small alternator as it only has 3 cylinders and 998cc then surely there is scope for a reduction in size rather than a full elimination in other vehicles ?

My though line is this - take a typical car which has been stripped for hypermiling - e.g. a Civic or something else. If you have reduced the electrical load (removing AC, extra lights, etc.) then you can live with a smaller (Aygo, but also Chevrolet Matiz) sized battery which also saves weight, and also a smaller alternator because anything bigger is a waste of energy as the battery is so small.

That way you get the benefits of saving on the alternator load vs what the engine had rated originally, less weight in a smaller battery but also get the convenience of a constantly charged battery whenever you use your car - like a conventional car.

EDIT - PS - plus this is nuts and bolts mods which are the simplest.

[EdKiefer]

Originally Posted by Arragonis

Why not just downsize ?

This may have already been covered or maybe is irrelevant so apologies in advance, I work in IT so I haven't followed the discussion on papers, watts etc.

I notice on my new "ride" (1 Litre, 3 cyl Petrol) that the battery is, well, tiny. I mean really tiny. I have an old style MGB which was designed with 2x 6 volt batteries of which I have 2 new ones, but the one in my new car is about the same size, if not smaller, than one of those.

Assume my Aygo also has a small alternator as it only has 3 cylinders and 998cc then surely there is scope for a reduction in size rather than a full elimination in other vehicles ?

My though line is this - take a typical car which has been stripped for hypermiling - e.g. a Civic or something else. If you have reduced the electrical load (removing AC, extra lights, etc.) then you can live with a smaller (Aygo, but also Chevrolet Matiz) sized battery which also saves weight, and also a smaller alternator because anything bigger is a waste of energy as the battery is so small.

That way you get the benefits of saving on the alternator load vs what the engine had rated originally, less weight in a smaller battery but also get the convenience of a constantly charged battery whenever you use your car - like a conventional car.

EDIT - PS - plus this is nuts and bolts mods which are the simplest.

The problem is many parts of the load you can't really do much ,at least on modern vehicle .
sure you can not use the Ac/heat, heated seats, rear defroster etc .
The things that eat up amps are things like fans , then you have the whole powertrain (ECU/ABS/VSA etc) so only thing you can do is not put any accessories but still the load will probably go over 15-30amp if cooling fans go on . Thats not counting headlights , I guess you could not drive at night but ...

Alternator already adjust output according to load so you would really have to strip/not use anything and still have a load .

[oil pan 4]

Has any one with a V-belt setup tried to build a belt quick release?
A 10% gain is amaizing, but the drive ability aspect leaves a few holes to be filled in.

[gone-ot]

56W = 4A × 14V

...or, about 1/13th of one HP (746W)

[California98Civic]

Originally Posted by oil pan 4

Has any one with a V-belt setup tried to build a belt quick release?
A 10% gain is amaizing, but the drive ability aspect leaves a few holes to be filled in.

I have seen people talking about it here, but I don't think it has been built. Unless I missed it in search this site. Use the search function. Have you considered an alternator kill switch? My understanding is that, "off," an alternator is not a significant drag. It produces drag when it starts generating--for small or large loads. What if you turned it off and only charged your deep cycle battery when your voltage gauge told you it was needed--and then only while coasting?

[oil pan 4]

Since I have a work truck that does more than move my butt around I was already planning on installing Marine starting and deep cycle batteries at some point (stock configuration is for 2 large batteries). I have a small 700 watt power inverter installed now and will likely get a much larger pure sine wave installed in the near future for running tools with out a generator, also have a flood light and will likely install a spot light and i am ready to install a 50 amp 12v air compressor when I have the time. I have also converted over to electric fans, electric cooling pump and electric fuel pumps.
This is why I have to keep an alternator for night time and PTO use.
I searched around and found:
"Electricly unhooking" the alternator seemed to net about a 5% gain.
Deleting or unhooking the belt seemed to be the real money maker, +10%MPG.

Just running off battery power alone isn't that appealing since each large marine starting battery I have been eyeing will run nearly $180 each.

I had already been considering a small solar panel to keep the batteries topped off in winter, now I am thinking about scaling that up.

[ConnClark]

I have been playing around with trying to design a circuit to replace/augment the rectification diodes with MOSFETs. I keep running into singularities at the moment but I will try and publish the results and circuit I come up with later.

I might be able to drop load on the engine by 1/4th a HP for every 30 Amps drawn.

[California98Civic]

Originally Posted by oil pan 4

I searched around and found:
"Electricly unhooking" the alternator seemed to net about a 5% gain.
Deleting or unhooking the belt seemed to be the real money maker, +10%MPG.

Just running off battery power alone isn't that appealing since each large marine starting battery I have been eyeing will run nearly $180 each.

I had already been considering a small solar panel to keep the batteries topped off in winter, now I am thinking about scaling that up.

So possibly half the gain is from disconnecting the belt? That would put the lie to what I was told about the big gain being in preventing the alternator from generating power.

For a solar panel, you might consider this company: 100w Solar Panel battery charger f boat,car.waterproof | eBay
They are the folks I have considered. The panel is thin and flexible, and I can fit a panel large enough for 120w on my Civic roof.

[oil pan 4]

I think it depends a lot on alternator speed and load.
You car guys are running your alternators on the highway at high speed with lowish draw (5 to 15) amps from an alt spinning at least 6,000 up to about 9,000.
I am sure I would see more than a 5% gain if I put enough solar on top of the suburban to run the electrical system since the alt runs at 100%+ at lower speeds.
I run my alternator at about 3,600RPM on the highway drawing up to 20 to 25 amps.
Using solar to cover coolant pump, fuel pump and fan losses sounds nice.

To sum it up I think I have more to gain by removing the electrical load only and you have more to gain by deleting the alt or removing the belt.