A fixed charging system without the $250 electrix parts?

[Nerobro]

After looking at the diagram for the alternator on a GS.... Why can't we just attach the parts from a standard car alternator and call it a day?

The alternator on a GS is 3phase, center tapped. Just like a car alternator. the diodes on a car alternator are generally setup to handle 60+ amps. So they are certinaly up to the task of regulating what's coming from our puny little stator. And they have a voltage regulator that's designed for 60amps + This would mean the failure point would be pushed down to the stator.

I'd also eliminate the "adjustable" capacity that suzuki designed in with the shutting off of one of the stator phases. Which seems to be what electrix does on their stator and rectifier replacements.

I read something about people using CB750 replacement parts... but why use "undersized" components from another bike when what are effectively superheavyduty parts are avaialble for $15 at your local car supermarket?

 

[Detman101]

something about the car alternator working at lower rpm's than our bikes and needing something to gear it up. Something like that I remember seeing somewhere...not completely 100% on it yet though.

:?
Dm of mD

 

[Nerobro]

I dunno about operating at lower rpms. But rpms wouldn't be the question. It's peak voltage that matters. So long as the peak voltages don't go above the breakdown voltages of the rectification diodes... (car alternators see more than 200volts at peak output) Then we should be ok. Along with having stronger components in the first place.

our alternator is geared 1:1 with the crankshaft. most car alternators are stepped up. the one on my focus is probally 1.5:1. so at redline the alternator is seeing 9000+ rpm.

I think it will work... In fact. In two weeks ;-) i'm gonna spend the $14 and give it a try. It can't hurt....

 

[Anonymous]

Hmmm..... In theory you're right. I wonder why nobody has tried it before... :roll:
Sounds logical to me. Are we missing something?

 

[Anonymous]

Doesn't a car voltage regulator control the system voltage by varying the alternator field current? What generates the field in a GS?

I thought I saw in another thread today that the GS regulator is a shunt regulator, which bypasses excess current to ground to maintain system voltage. That's why one phase of the 3-phase stator is opened when the headlights are off - so it won't generate the excess current in the first place. If the GS regulator IS a shunt regulator, that tells me the GS's field isn't controlled, and a car regulator won't regulate.

Dave

 

[Nerobro]

Ah hah! That just might be the problem. However, that does not mean all is lost ;-) It just means I'll need to find a "shunt" voltage regulator to do the job. In fact, the one on the GS, using the ziener diode is just that. That's an easy part to find.

 

[bwringer]

My first bike back when I was a poor college student was a GS400.

I was having problems with poor charging, and it turned out the permanent magnets in the rotor had lost much of their charge over the years. The stator and R/R were fine -- they were never in much danger from the pitiful dribble of electrons.

Anyway, I presented my Dad with my dilemma and, after a flurry of muttering and sketching, he built a replacement R/R in about 15 minutes using a few bucks worth of parts scrounged from his basement lair. His version only had a small heat sink, and the idea was that it rectified and regulated in some way that wasted far fewer precious electrons and as a side effect, generated far less heat. The small heat sink never felt more than slightly warm.

I still had to keep the battery charged, but the problem was much improved. Instead of dying on the way to class, I could ride for a couple of days before charging the battery. I normally just plugged the battery into an automatic charger every night.

The bike was still wearing its homemade R/R when I sold it four years later, and it was still working fine. I don't have the vaguest idea how Dad did it, but I think it somehow involved extremely fast current switching. There was an IC in the middle of the tangle, I think. The regulation seemed very smooth -- you didn't see the usual small constant variations in headlight output. It would get slightly brighter as you revved the engine, since output at idle was below the set point.

Oh, did I mention Dad is a top-flight electronic instrument design engineer? That probably helps... I'll ask him about his magic regulator/rectifier next time I visit.

The bit about the different methods of regulation in (most) bikes vs. cars is exactly correct. Our bikes use permanent magnets in the rotor to generate the necessary magnetic field. Cars use electromagnets to perform the same function, and regulate output by controlling the strength of these fields.

Of course, some other bikes have alternators that work the same way as car alternators, but never mind that.

 

[Sandy]

I'm just experimenting with this exact conversion. Last night I wired up a three phase automotive diode plate I bought new for $10.00. I don't have it regulated yet because I wanted first to find out how much DC it's putting out. I wired all three coils from the stator directly to the three diodes and fired it up. At low RPM, say just off idle and at idle it puts out between 25VDC and 35VDC, at 6,500 rpm it breaks the 100VDC barrier and with a quick blip past that I saw around 120VDC. Now I'll have to track down some sort of DC to DC regulator for it when I get back from holidays. If someone has found one by then please post it.

 

[DMPLATT]

Anyway, I presented my Dad with my dilemma and, after a flurry of muttering and sketching, he built a replacement R/R in about 15 minutes using a few bucks worth of parts scrounged from his basement lair.

Cherrish your dad. My Dad was the same way. I sometimes took him for granted. I lost him about 2 years ago and feel lost without him. I used to call him all the time as he was a Genius with mechanical and electrical. Even if he didn't know, after about 5 minutes of talking with him we could figure just about anything out. What a mind. Your dad sounds like the same kind of man. I'm certain that with my Electronic Tach mess, he would have either solved it by now or built me a better one. :lol: :lol: He was 87, so had a good life, but he was an old farmer that grew up with engines and spent 23 yrs. with the Army Aircorp (Air Force) and was a genius with electronics. Too bad some more didn't rub off. :lol:
God Bless.

Dave

 

[Anonymous]

I'm sure I read somewhere - either in archives or on a V4 honda site, that someone was doing experimnentation with a modification that involved separate regulators and rectifiers. Perhaps someone out there knows more about it? I'll search my files anyhow.

BTW I also saw a mod with the fan from Pentium V computor mounted on reg/rec which aparently was very successful in lowering temperatures.

I think the basic theory in both cases was that the main criteria was the need for 12 volt system parts, and many NON_BIKE parts are built with higher load tolerances.

All this from a guy who knows nothing about mechanical or electrical thingys.

 

[Nerobro]

What your dad made was a switching power supply. they're complex to make. they are what modern PC power supplies use. I have six driver chips for these kind of power supplies. they are VERY efficant. As much as 95%. that's why it didn't get hot ;-) Switching power suplies run from khz to mhz in switching frequency. they work through the interplay of capacitors and coils. coils are resistant to changing current. Capacitors are resistant to changing voltage. by variing the pulse width of the high dc voltages coming from the alternator into the coil you can get the voltage to average out to what you want it at.

They're much more complex to build. But "doable" If he's willing to throw some plans our way, I"m sure we coudl make them. (I am working on building a laptop power supply, tha'ts why I have the driver chips....)

I was hoping for a simpler solution. Without using a circut board. Using a linear power supply. but those get freaky hot when regulating... sorta like the stock GS bits.

 

[Nerobro]

Now I'll have to track down some sort of DC to DC regulator for it when I get back from holidays. If someone has found one by then please post it.

hit www.digikey.com type in voltage regulator. There are many single chip solutions.. But many can't handle the current output maybe using 4-5 of them in parallel bolted to an aluminum plate... or the heatsink off a P2 chip. cheap, easy.

they also have switching power supplies in a single chip.. but you still need to add a coil and a capacitor. Hmm........ *looks at the breadboard in the bathroom* Maybe I'll get to use it.

 

[bwringer]

Cherish your dad. My Dad was the same way.

Don't worry, I do! I'm going to take Dad to the Indianapolis Air Show next weekend, which means putting up with an all-day rapid-fire stream of technical chatter. I'm one of the few who can keep up with him, but it's exhausting. When my attention starts to wander away, he uses the Socratic method mercilessly to wake me up.

I'm also fortunate to still have my Grandpa (my Dad's Dad) around. He's in his '80s and can't travel too much, but has the same sort of Vulcan mind for machinery. When I bought my GS about 6 years ago, it was the first four-cylinder motorcycle my Grandpa had examined closely -- he was more familiar with Hardleys from the '50s. After a quick walk-around, he absorbed the main priciples of the machine instantly and started asking very detailed technical questions about the shaft drive, the transmission, modern tires, brakes, etc.

Anyway, I'll be seeing Dad and Grandpa soon, and I'll ask Dad about the regulator/rectifier he built. They'd both be utterly baffled by any conventional display of affection, but I always make sure I bring them some knotty problem to solve instead!

Now back to the main topic...
The Electrex R/R is a conventional design that's simply made more robust, correct? It's not a fancy switching regulator or anything.

I'll talk with Dad about better alternatives to the traditional motorcycle R/R (less heat generated, less power lost), and if I can extract some diagrams and info from him, I'll be happy to post what I can find out for the GS crowd.

Of course, it would also have to be small enough to fit (plenty of space in my GS) and there would probably need to be a way to protect it from vibration, corrosion, water, etc. (potting compound?) Would there be any benefit to being able to adjust the output voltage? I remember Dad sorting through a pile of cheap crappy Radio Shack components (resistors, I think) to find one that was a little further out of tolerance so he could set the voltage a bit higher.

 

[joe.d]

Hey all this electro talk is making my Head spin.....
My dad bless is heart, asked me how many buckets of water he put in our washing machine

 

[Anonymous]

Although, how would a switching power supply work without toasting the stator? Since our stators use a permanent magnet, they always generate the same amount of wattage for a given RPM, right?

If that's the case, making a more efficient power supply is dangerous unless you can use up all the reclaimed wattage that you got back by raising the efficiency. If you don't use it, the stator windings will heat up instead and 'use it' for you in a bad way ..


Now, I could be way off base here..

 

[Anonymous]

Although, how would a switching power supply work without toasting the stator? Since our stators use a permanent magnet, they always generate the same amount of wattage for a given RPM, right?

Wattage is based on the load, not the generator. If you open the output of the stator, there's no load and no wattage. Shouldn't be a problem. (That's basically what the headlight trick does - opens one phase of the stator.)

The one thing that opening the output will do is cause a very high voltage at the stator output. The rectifiers have to be rated to take the high voltage AND source the entire current used by the bike. (Anybody know what that is?) Also, the regulator circuit itself must be able to handle the high voltage coming off the stator.

Switching supplies are very efficient. In fact, it wouldn't surprise me if a stator lived longer with a switcher since it doesn't need to generate as much current when the electrical system is lightly loaded.

Dave

 

[Nerobro]

The voltage spikes are/can/will be filtered by a moderately sized capacitor...

 

[Anonymous]

*ahem* bump

This one peeks my interest.