Regarding Charging System Failures

[Stretch]

I'm still reading up on motorcycle charging systems, trying to find a way to prevent the failures that seem to plague Girlies.

A primer:

The charging system on a Girly consists of an Alternator and a Voltage Regulator / Rectifier.  The Alternator is different from those on a car in that our Alternator consists of a permanent magnet (rotor) spinning around a stationary Stator.  The spinning magnet produces electricity by exciting the electrons in the coils of copper wire built into the Stator...



The new electricity flows from the copper coils into wires which send the current to the motorcycle.

Alternators produce Alternating Current, the same type of current used in your house, but at a lower voltage, around 70 Volts AC.  Alternating Current flows back and forth 60 times a second... this is the 60 Hertz or  60 Cycles that you may have seen written on household appliances.  

This AC current is then sent to the Rectifier half of the Regulator / Rectifier...



Diodes convert the Alternating Current to Direct Current, that which is used in cars, bikes, trucks, etc.  Think of a Diode as a one-way valve.  They let the Alternating Current flow into the Rectifier, but not back out.  This produces Direct Current, which flows in one direction only.

The current is then sent into the Regulator, which then chops off the amount of DC the battery can't use and dumps it to Ground (DC -).  This is why the Regulator / Rectifier gets so hot... it is dumping excess electricity from the charging system and converting it to heat.

This is typical of most Regulator / Rectifiers found on most 2003 and earlier bikes, the shunt-type R/R (so named because it shunts excess current to Ground).  These units referred to as 'SCR' Regulator / Rectifiers, meaning Silicone-Controlled Rectifier.

The voltage put out by the RR is dependent on the temperature of the RR.  When it's cool, it puts out higher Voltage.  As the RR warms up, the output voltage drops.

Now then...

One possible cause of charging system failure is alternator stator failure caused by one of the phases (groups of the copper coils) shorting to ground.  This might be the result of pinched wires inside the stator cover, or frayed insulation on a wire.  This is easy to test... using a Volt-Ohm Meter, there should be Infinite Ohms (an open circuit) between any Stator wire and Ground.  If your meter shows 0 Ohms (continuity, or a closed circuit), that leg (phase) of the stator is shorted to Ground, and the Stator is shot.

Another possible cause may be bare spots in the insulation on the wires that make up the windings on the poles of the stator.  Motorcycle Voltage Regulators are able to handle high Voltage from the stator, but only low current (Amperes).  When the coils of small-gauge wire short against themselves, they artificially create fewer coils of larger wire, producing too much Amperage for the Voltage Regulator to handle, frying the Regulator.

Although these two causes are possible, Stator failures by themselves aren't as common as Voltage Regulator failures.  When a Regulator goes, it frequently takes the Stator with it, by shorting and / or overloading the phases (groups of copper coils).  For this reason, it is recommended to replace both the Stator and Regulator / Rectifier (at the same time) when repairing a charging system failure.

It's much more likely to experience a Voltage Regulator / Rectifier failure.  Remember my comment above about the Regulator / Rectifier dumping excess electricity to ground, causing the RR to get hot?  Well, they're made to take some heat, but they do need some airflow to keep cool.  That's why they have cooling fins, just like the cylinders and heads of air-cooled engines.  A Regulator / Rectifier will burn out internally if its temperature isn't kept to a safe level.  And where does Triumph put them?  Under the seat, between the frame and the battery box.

I firmly believe that the number of charging system failures can be reduced by getting the RR to run at a cooler temperature.  I'm going to do a bit of experimenting with the side cover, maybe a small air scoop to get air to the RR... maybe moving the RR altogether and getting it on the outside of the bike where the cooling fins can actually get some air.

I learned a great deal bout the kind of charging systems in Girlies by reading this thread on F650.com, a site dedicated to BMW F650's, which run a very similar type of charging system.  F650's are also plagued with charging system failures, but from reading here, most seem to be attributed to RR failures caused by excessive heat buildup.

http://faq.f650.com/FAQs/VoltageRectifierFAQ.htm

[HappyMan]

Nicely written Stretch.  Thanks.  If this isn't already a sticky it is worth considering.

[Mustang]

On the old bonnevilles (pre 1971) they were mounted in the air stream under the headlamp , the new bonnies are the same way .
The oil frame bonnies after 1971 were not they had a zener diode mounted in the air box with the rectifier under the seat , guess which one failed all the time .

[Mustang]

you have already found the problem it is HEAT you need to get that regulator rectifier out into the fresh air somehow .

[Stretch]

Do you think there would be a significant voltage drop (due to long wires) by moving the RR to the front of the bike, maybe under the fairing?

[HappyMan]

I knew there were some pluses living in a colder climate.  8)

[Mustang]

what's worse .......loosing a little voltage or constantly going thru R/R

[Stretch]

Maybe a thick heat sink bolted to the back of the RR, made of aluminum.

We have an Infra-Red camera on my fire engine, which we use to look for fire and smoke victims in structure fires.  Even in a hot, smoky room, the silhouette of a human stands out sharply against the floor, bed, etc.

My point:  We take it out and play with it sometimes... I mean, uh... train with it, to make sure we stay familiar with it.  We had been out on a call earlier, and had been back in the house for a few minutes, and I pointed the camera at the aluminum wheels on the truck... the were dark gray on the IR camera, indicating cooler temperatures.  But you could see the brake rotor through the holes in the wheel, bright white, indicating high heat.

The aluminum wheel was much cooler than the iron brake rotor, as aluminum gives off heat more quickly.  It also heats up quickly, sapping the heat away from the hot brake rotor.

Soooo...  a thick slab of aluminum bolted to the back of the RR ought to rob a lot of heat from it.

Hmmmmm...

[Stretch]

what's worse .......loosing a little voltage or constantly going thru R/R

No kidding.

A thick heat sink and relocate the RR into the air.

I think we may be on to something.

[HappyMan]

So is my 06 going to suffer a similar fate?  Out of curiosity what did they do with the Roadies?

[Mustang]

Instead of just a pc of aluminum to mount to



a nice alum. heat sink with the center machined out to match the shape of the R/R would work so much better

[Mustang]

So is my 06 going to suffer a similar fate?  Out of curiosity what did they do with the Roadies?

Not nessacarily , but you do read about a lot of Girly bikes given it up to charging problems
It is much colder ambient air temp up in cheeseland though , it does make a difference

[Stretch]

Who's to say which RR will fry and which won't?  There are dudes here with 75k, 100k miles and more with the original charging systems.

And others have been through a couple or more in half the time.

It must also have something to do with the quality of connections between the RR and Ground.  Crappy connections create heat, and with the RR creating its own heat by regulating the Voltage, the added heat of resistance just makes things worse.

So add that to the list...

Relocate the RR into airflow, thick aluminum heatsink, and scrupulously clean connections throughout the charging system.

[Mustang]

Sounds like you have a mission ........I'm out going night night

[Stretch]

Instead of just a pc of aluminum to mount to



a nice alum. heat sink with the center machined out to match the shape of the R/R would work so much better

From an electronics supply house, I presume?