Alternator power loss

the fly <tsetse51 DeleteThis @swbell.net> wrote:
 > On Thu, 16 Sep 2004 17:41:37 GMT, Ted <tedbennett DeleteThis @earthlink.net>
 > wrote:
 >
  >>It's a rare circumstance when the full rated wattage of an alternator is
  >>used to power electrical accessories. Is it correct to assume that any
  >>excess capacity is simply bled off as heat from the regulator?
  >>
  >>If that is so, that is obviously detrimental to the overall efficiency
  >>of the engine. Are there any alternators which can vary their output
  >>according to demand?
 >
 > Most all regulated alternators only produce as much power as
 > necessary for the load. That's what the regulator is there for. It
 > feeds current into the field coil, with the amount dependent on system
 > voltage sensed. When the voltage drops (load applied), the regulator
 > strengthens the field, inducing more current in the stator.

This is correct as far as it goes, assuming the bike has an excited
field alternator. Some bikes have permanent magnet alternators,
which typically short one or more phases to regulate output, which
dissipates some power due to winding resistance and forward drop of
the SCR used to short the phases, but not anywhere near max output
minus system load.

There have in fact been some charging systems which used a Zener diode
regulator. In that case, it is true that any power in excess of what
was needed to satisfy the load would be converted directly into heat,
up to whatever max output the dynamo was capable of producing (which
probably wasn't much).

--
Mark '01 SV650S '99 EX250-F13 '81 CM400T<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Alternator power loss 

 >From: Ted tedbennett.TakeThisOut@earthlink.net

 > Are there any alternators which can vary their output
 >according to demand?

Sure. The excited field alternator. It's the standard power generating
alternator that planes, trains, cars, and hydroelectric plants use. I have
worked on excited field alternators that were so big you could crawl around
inside them, and have worked on excited field alternators small enough to hold
in one hand...

Very few motorcycles ever had excited field alternators, which resemble a car's
alternator and are mounted behind the cylinder block, below the carburetors,
with diodes built into the case and regulator by an integrated circuit chip...

24 hour endurance racers back in the 1980's needed a superior alternator to
light huge driving lights while circling the Bol d'Or race track at midnight,
so we started seeing car alternators grafted onto a stub axle attached to the
countershaft sprockets of endurance race bikes...

In the late 1980's Yamaha, Suzuki and Kawasaki started installing car type
alternators driven by a gear of the clutch, or in the case of some Kawasakis,
vee belts off the clutch...

But excited field alternators seem to be passing out of style, but I could be
wrong, so check for yourself...

My Suzuki GSXR-750 has a car type excited field alternator, and so does my
Yamaha FZR-1000, both driven off the clutch primary gear, and my Suzuki GT-750
2-stroke triples had excited field alternators on the end of the crankshaft
with an electromechanical regulator that had coils and contacts...

I think Kawasaki sportbikes, like the ZX-7, also had excited field alternators,
some driven by rubber belts...

My FZR-1000's excited field alternator is chain driven...

Suzuki, in particular, had a lot of problems in the early 1980's with permanent
magnet alternators mounted on the end of the crankshaft, spinning at high
speed. The heavy rotors would loosen up and spin off the end of the crankshaft
and the stator coils were forever being fried when any of a number of problems
occurred with the battery, the shunt type rectifier regulator that dissipated
excess power as waste heat, or with the bike's wire harness...

So, I thought that Suzuki had "seen the light" about the excited field
alternator's superiority to the permanent magnet type...

But, when Suzuki introduced their line of 90-degree vee-twins to capture part
of Ducati's market, the danged things had permanent magnet alternator bolted to
the end of the crankshaft...

So I asked the Suzuki tech rep at the Long Beach motorcycle show what was up
with that backsliding...

And he replied that *Honda* had a patent (at least in Japan) protecting their
rights to use excited field alternators on their offerings, and that if Suzuki
wanted to use the superior alternator, they would have to pay royalties to
Honda for the privilege!

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krusty kritter wrote:

 > Suzuki, in particular, had a lot of problems in the early 1980's with permanent
 > magnet alternators mounted on the end of the crankshaft, spinning at high
 > speed. The heavy rotors would loosen up and spin off the end of the crankshaft
 > and the stator coils were forever being fried when any of a number of problems
 > occurred with the battery, the shunt type rectifier regulator that dissipated
 > excess power as waste heat, or with the bike's wire harness...
 >
 > So, I thought that Suzuki had "seen the light" about the excited field
 > alternator's superiority to the permanent magnet type...
 >
 > But, when Suzuki introduced their line of 90-degree vee-twins to capture part
 > of Ducati's market, the danged things had permanent magnet alternator bolted to
 > the end of the crankshaft...
 >
 > So I asked the Suzuki tech rep at the Long Beach motorcycle show what was up
 > with that backsliding...
 >
 > And he replied that *Honda* had a patent (at least in Japan) protecting their
 > rights to use excited field alternators on their offerings, and that if Suzuki
 > wanted to use the superior alternator, they would have to pay royalties to
 > Honda for the privilege!
 >
 >

What's so special about Honda's crank mounted alternators? Does it use
fixed field coils and a rotating armature?<!-- ~MESSAGE_AFTER~ -->
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"krusty kritter" <kaybearjr DeleteThis @aol.comical> wrote in message
news:20040916213849.10984.00000665@mb-m14.aol.com...
| >From: Ted tedbennett DeleteThis @earthlink.net
|
| > Are there any alternators which can vary their output
| >according to demand?
|
| Sure. The excited field alternator. It's the standard power generating
| alternator that planes, trains, cars, and hydroelectric plants use. I have
| worked on excited field alternators that were so big you could crawl
around
| inside them, and have worked on excited field alternators small enough to
hold
| in one hand...
|
| Very few motorcycles ever had excited field alternators, which resemble a
car's
| alternator and are mounted behind the cylinder block, below the
carburetors,
| with diodes built into the case and regulator by an integrated circuit
chip...
|
| My Suzuki GSXR-750 has a car type excited field alternator, and so does my
| Yamaha FZR-1000, both driven off the clutch primary gear, and my Suzuki
GT-750
| 2-stroke triples had excited field alternators on the end of the
crankshaft
| with an electromechanical regulator that had coils and contacts...
|
| Suzuki, in particular, had a lot of problems in the early 1980's with
permanent
| magnet alternators mounted on the end of the crankshaft, spinning at high
| speed. The heavy rotors would loosen up and spin off the end of the
crankshaft
| and the stator coils were forever being fried when any of a number of
problems
| occurred with the battery, the shunt type rectifier regulator that
dissipated
| excess power as waste heat, or with the bike's wire harness... (SHORTS)
|
| So, I thought that Suzuki had "seen the light" about the excited field
| alternator's superiority to the permanent magnet type...
|
| But, when Suzuki introduced their line of 90-degree vee-twins to capture
part
| of Ducati's market, the danged things had permanent magnet alternator
bolted to
| the end of the crankshaft...
|
| So I asked the Suzuki tech rep at the Long Beach motorcycle show what was
up
| with that backsliding...
|
| And he replied that *Honda* had a patent (at least in Japan) protecting
their
| rights to use excited field alternators on their offerings, and that if
Suzuki
| wanted to use the superior alternator, they would have to pay royalties to
| Honda for the privilege!
|
| # * 0 * #
| ^

Go Figure. If thats so (Honda Patent) Why does my Shadow Ace have a
permanent-magnet alternator,
with the voltage regulator assembly mounted below the battery (heat
dissapation?) Maybe the V-twin's
engine speed doesn't build up enough field to over-load the regulator? (I
wish they'd built a tach. on the
Shadow's, along with a Fuel Gague...)
Lefty
 >> Stay informed about: Alternator power loss 

 >From: "'Lefty'" kk1NOSPAMa RemoveThis @arrl.net

 >Why does my Shadow Ace have a permanent-magnet alternator, with the voltage
regulator assembly mounted below the battery (heat dissapation?)

Well, maybe the design team at Honda looked at the cruiser lifestyle and
decided that most cruisers probably
just slowly putted down to the boulevard at night and hung around the hamburger
stand for an hour and went back home to the old ball and chain and really never
went far enough at night to justify more than a minimum lighting system and a
minimum generating system to keep the battery charged...

I used to hang around with those cruiser guys on the boulevard, so I know what
that lifestyle is all about...

It ain't the Iron Butt Rally, that's fer sure...

I talked to a guy several years ago who had his ST-1100 all rigged out for Iron
Butt, with driving lights, heated handgrips, coffee cup and water bottle
holders on the handlebars, an auxilliary gas tank, radar detector, and on and
on...

A guy like that needs a heavy duty electrical system, but the rest of us could
get home with a flashlight if we had to...



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On 17 Sep 2004 23:47:16 GMT, kaybearjr DeleteThis @aol.comical (krusty kritter)
wrote:

 >I talked to a guy several years ago who had his ST-1100 all rigged out for Iron
 >Butt, with driving lights, heated handgrips,

These use electricity.

 > coffee cup and water bottle holders on the handlebars, an auxilliary gas tank,

These don't.

 >radar detector,

This uses very little.

 >and on and on...

Don't forget GPS and heated clothing.

 >A guy like that needs a heavy duty electrical system, but the rest of us could
 >get home with a flashlight if we had to...

Most Hondas have a permanent magnet type alternator, and it's been
like that for years. There are fewer moving parts and except for a
melting connector between the stator and regulator/rectifier, they are
problem free for the most part.


--
Jack<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Alternator power loss 

 >From: Jack Hunt jhunt1x.RemoveThis@earthlink.net

 >Most Hondas have a permanent magnet type alternator, and it's been like that
for years. There are fewer moving parts and except for a melting connector
between the stator and regulator/rectifier, they are problem free for the most
part.

I was under the impression that excited field alternators would always have a
higher magnetic flux density than
permanent magnets and therefore they would have a greater output...

Output from an alternator is a function of RPM, flux density, and the number of
turns in the stator's windings. RPM affects the inductive reactance of the
coils, the impedance increases as RPM rises...

But an EE on another group checked with his colleague, who was an expert on
magnets and the magnet guy said that it was possible to have a stronger
permanent magnet than was possible with electromagnetism....

I was also told that the reason cars went to alternators from DC generators in
the 1960's was because alternators did a better job of charging the battery at
idle RPM...

Maybe car alternators have a smaller drive pulley and are turning faster than
the old DC generator?

Or maybe car alternators have more pole pairs than DC generators had? Who
knows?

I figured that an alternator running off the motorcycle clutch was turning at
clutch speed and doing a better job than an alternator running at higher speed
on the end of the crankshaft...

But, then somebody else pointed out that the EF alternator running off the
clutch gear had a smaller reduction gear and was probably turning just as fast
as
a PM alternator bolted directly to the crankshaft...

So, what the heck do I know about PM alternators vs. EF alternators? Just from
experience, I can say that my GS-1100 with the PM alternator always had a dead
battery, but my FZR and GSXR's batteries last for years and years...

The original battery on my GSXR lasted 5 years, and the FZR battery lasted for
8 years. Both of those have EF alternators...



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On 18 Sep 2004 03:00:15 GMT, kaybearjr.DeleteThis@aol.comical (krusty kritter)
wrote:

 >I can say that my GS-1100 with the PM alternator always had a dead
 >battery, but my FZR and GSXR's batteries last for years and years...
 >
 >The original battery on my GSXR lasted 5 years, and the FZR battery lasted for
 >8 years. Both of those have EF alternators...

This is more a result of battery construction and maintenance, and
regulator efficiency than alternator type. It's rare to find a
motorcycle battery that lasts more than 4 years no matter which type
alternator it has.

A PM alternator is putting out near 100% at anything over 1500rpm.

I'm old enough to have had vehicles with DC generators. My first
street vehicle was a 6-volt '56 Dodge flatbed pickup truck with the
starter pedal in the floor and a flathead straight six and a bulldog
transmission. The biggest generator I ever saw on a passenger vehicle
was about 20-25 amps. Most were about 15. Most alternators put out
more than that at idle and some can do 100 amps or more. It would
take hours to recharge a dead battery on my old VW dune buggy with the
tiny DC generator.

My mid-80s bikes had ~280 watt PM alternators and never had any
battery problems. My '91 ST1100 had roughly the same size alternator
and never gave any problems. My '99 has a bigger alternator and
hasn't given any problems in the last 25,000 miles.

There probably is a greater tendency of PM systems to boil a battery
dry and therefore shorten its life. Frequent checks or a sealed
maintenance free battery would greatly extend battery life.

I had 100 extra watts of light, a radar detector, a GPS, and a cell
phone charger on my '83 VF750C with the 280 watt PM alternator and
never ran out of juice.

I added a single extra light, probably 50 watts or less, on my old HD
with the tiny DC generator and the battery went dead while I was
riding. I never titled that bike, just thrashed it around on tracks
and back roads. I was in the middle of a power slide with engine rpm
in the upper third of the range when it just died. The MSF will tell
you that you'll crash if that happens. I didn't.

--
Jack Hunt IBA#12795
'99 ST1100
'95 Suzuki DR250SE, Dr. Zook
'83 V45 Magna
'85 V65 Magna (x2)
'85 V65 Sabre
'91 ST1100
'74 CB360
'7? HD
and a host of single cylinder Japanese bikes that came to my place to
die in the early 70s.<!-- ~MESSAGE_AFTER~ -->
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On 18 Sep 2004 03:00:15 GMT, kaybearjr.DeleteThis@aol.comical (krusty kritter)
wrote:

 >
 >I was also told that the reason cars went to alternators from DC generators in
 >the 1960's was because alternators did a better job of charging the battery at
 >idle RPM...
 >
 >Maybe car alternators have a smaller drive pulley and are turning faster than
 >the old DC generator?
 >
 >Or maybe car alternators have more pole pairs than DC generators had? Who
 >knows?

  The main reason for the change from DC gen to alternator was
the fact that all output current from a generator had to travel
through the brushes at the commutator. The field coils were
stationary, and the main output current was induced in the rotor.
Arcing and wear limited the output, and required much more frequent
repair.
  In modern alternators, the field current (maybe 2-5 amps) is
carried via brushes, (still the source of most service problems),
through slip-ring contacts, to the field coil in the rotor. The main
charging output is induced in the stator windings.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Alternator power loss 

 >From: the fly tsetse51 DeleteThis @swbell.net
  >The main reason for the change from DC gen to alternator was the fact that
all output current from a generator had to travel through the brushes at the
commutator. The field coils were stationary, and the main output current was
induced in the rotor. Arcing and wear limited the output, and required much
more frequent
 >repair.

Whether it's called a "generator" or an "alternator", the same thing happens in
whatever windings are going to produce the power: *alternating current* is
induced in that winding by the constant reversal of current due to passing from
north pole to south pole of the magnetic fields, and the AC has to be changed
into DC for your battery to take advantage of it. Your lighting system doesn't
care if it's AC or DC...

A commutator is a mechanical rectifier which changes AC into DC by having a
brush pair aligned with two commutator segments which have the AC current on
the positive alternation and a pulsating DC current is the output...

There were no reliable solid state diodes available until the 1960's, so when
good diodeds became available, there was no need to mechanically rectify the AC
output from the so-called DC generator...



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 >From: Jack Hunt jhunt1x.DeleteThis@earthlink.net

 >I'm old enough to have had vehicles with DC generators. My first street
vehicle was a 6-volt '56 Dodge flatbed pickup truck with the starter pedal in
the floor and a flathead straight six and a bulldog transmission.

My first car was a 1951 Oldsmobile Rocket 88. I had lots of generator problems
with it, mostly from tinker-itis...

Somebody showed me how to adjust the voltage by turning a screw in the
electromechanical points-type regulator, so I did that, and fried the generator


When a commutator with soldered armature windings gets very hot, it will sling
the solder out of the commutator...

I did that at least twice on the Oldmobile and once on my 1957 Jaguar sedan

The oldest car I ever owned was a 1935 Auburn cabriolet with the exhaust pipes
sticking out through the side of the hood. It was a strange sensation, sitting
about six feet above the ground, with a hood sticking out 10 feet ahead of
me...

The Auburn wasn't a boat-tailed speedster, it had roll up windows and a rumble
seat and two spare tires in the front fenders. It was a marriage wrecker,
though. The guy who owned it spent all his time and money working on it and his
wife left him to go back to her mother. He offered to sell it to me at a
sacrifice price and went chasing her back to Georgia.

I had no idea that it would be worth about $100K some day and sold it for less
than I paid for it...



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I am the original poster of this interesting thread.

Thanks to everyone for your contributions, and now I have another
question about electrics. My ignorance is vast.

My battery seems to be rather weak, as it won't make the turn signals
flash unless the engine is running. They just light up and stay there.
The bike starts up fine because it doesn't have a self starter.

How do I determine if my battery is toast, and do I even need the thing
anyway? I can't see much reason for it unless it provides some
buffering or capacitance for the alternator, or unless I run wires from
it so I can listen to my radio while lying in my tent.
 >> Stay informed about: Alternator power loss 

On Sat, 18 Sep 2004 23:20:48 GMT, Ted <tedbennett RemoveThis @earthlink.net>
wrote:

 >I am the original poster of this interesting thread.
 >
 >Thanks to everyone for your contributions, and now I have another
 >question about electrics. My ignorance is vast.
 >
 >My battery seems to be rather weak, as it won't make the turn signals
 >flash unless the engine is running. They just light up and stay there.
 >The bike starts up fine because it doesn't have a self starter.
 >
 >How do I determine if my battery is toast, and do I even need the thing
 >anyway? I can't see much reason for it unless it provides some
 >buffering or capacitance for the alternator, or unless I run wires from
 >it so I can listen to my radio while lying in my tent.



It sounds like your charging system is working.
Ty charging the battery.
If the problem persists, have the battery tested or replaced.
BTW, when asking for help, give as much info on the bike as possible.
Year, make, model etc.<!-- ~MESSAGE_AFTER~ -->
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