K11 Owners Group

[Flying Duck]

Since installing a voltmeter in my K1100RS I've discovered something about having an LED in the charge warning lamp which I'd suspected earlier. As some of you have emailed me, after starting the bike the charge warning lamp remains lit until you rev the bike up to 2500 rpm or so. That means that the alternator is NOT charging the battery and that your bike is running off of battery power. Once you've rev'd it though and the light goes out then the alternator is working to run the bike and keep the battery charged. Revving the bike like that "excites" the circuitry in the voltage regulator, the alternator kicks in and the charge lamp goes out. When you let the bike drop back down to idle the alternator will keep running the bike and charging the battery.

This really isn''t an issue as far as I'm concerned but don't start your bike and let it sit idling without revving it until the light goes out or you can kill your battery. I found this out the hard way last summer at 11pm in a Kansas rest area in the middle of nowhere. I started the bike and let it idle with the red light on while diddling with my GPS power supply and the bike eventually died on me when the battery ran down. I had to hang out there for almost an hour before someone with jumper cables finally pulled into the rest area. DOH! This would not have happened if I'd just revved it once until the light went out.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[jpberens1994K1100RS]

Mmmmmmmmmmmmmmmmmm.

What's wrong with my 93 RS ? Almost 40K on it now.

Starts right up, that red light goes out instantly. I don't touch the throttle, but do use the enrichment lever. Revs do not go over 1,500. I know not up & over 2,500.

I like the LED kit, gauges too. Dig that " Batman " green glow.

Now that daylight saving time is here, I get a lot of opportunity to ride in the dark. Always use the CATZ XLO's, day or night.
_________________
1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge

[Tim (Midland Section)]

The charge lamp is used to supply current to energise the alternator rotor.
As LEDs use much less current it aint enough. Just like the BMU problem.
A resistor of suitable value, in this case about 30 Ohms 3 Watt rating should be wired in parallel with the LED.
HTH
_________________
Regards Tim,

Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
#485

[Flying Duck]

[Tim (Midland Section)]

[Flying Duck]

[RobWheatley]

Electronics 101

Right an LED is an electrical one way valve, it will ONLY pass current one way, if it is used on an charge warning light you will get what duck is, the alternator wont start to charge.
The way it normally works is the charge warning light puts a small amount of power INTO the rotating alternator coils (which are connected to ground one end) via the slip rings, when at rest (or turning too slow to produce power) the coils will cause the bulb to light as there will be a current flow to ground through it (there is a differance in the voltage, +12volt coming from the ignition switch via the bulb and lower coming from the alternator (+12 volt and say + 7 volt from the coils make a voltage flow of +5 volts making the light glow) the power going into the coils excites them producing a magnetic field, when they are turning quick enough they will then excite the LARGER fixed coils that are connected to the regulator and diode pack (this is where the power output comes from)
as soon as the alternator is putting out 12 volts the light will go out (+12v & +12v = 0v diff) Now you might be saying "but my alternator charges at 13-14 volts and the battery is 12v so the light would glow when its charging" wont happen as the output from the alternator is connected to the battery too, when the alternator puts out 14v, the battery + post will be at 14v too.

With an LED in place of the bulb what happens is the LED needs very little power to light and wont excite the coils properly until the rotor is turning faster, hence having to rev to 2500 to put the light out.

On a bike (or car) fitted with an alternator if the battery is totally flat (and I mean dead as in 0 volts) the alternator wont be able to produce power at all (unless as Tim says there is residual magnetic fields in the coils) as it needs the + 12v going in to work, same as if the charge warning light circuit/bulb fails.

Rob
_________________
1999 K1100LTIC Smooth and Quiet Cruise, BFD & HID
1996 K1100RS. dead but not forgotten.

[Flying Duck]

[supercat1]

as a recent engineering grad, I feel like that was covered in my basic circiuts and physics 2 course. Granted the circuits corse was a 300 level. The only thing there that isn't pretty basic is knowing the actual layout of the bike's circuitry. Thanks for the info!

oh and I didn't know that leds were one way.
_________________
(formerly) 1993 k1100rs

[Scott_Anderson]

SuperCat, I'm not picking on you, but

[supercat1]

well, it may or may not be the system. I did know what led stood for. However the course I took was not for ee's. It was for all other engineering students and did not focus on the equipment or parts in circuits but rather the analysis of circuits. Aside from capacitors, resistors, power sources, and inductors I don't think we covered any other hardware because inside an office building that is generally what is present. The professor was still able to present plenty of differential equations and required use of laplace transforms just for that. So yeah, not nevessarily the system so much as not the topic or intended content of the course. My roommate spent some time as an ee and I do know they took different courses that covered all that at the beginning and had labs. t the course I took did not.

or I could have just forgotten that info since I took the class.
_________________
(formerly) 1993 k1100rs

[Tim (Midland Section)]

Rob, Thanks for saving me all that typing. What's Electronics 101, 200 & 300?
I have a B City & Guilds in telecomms & an Amateur (Ham) Licence. Got my electronics from my dad (RIP) & reading.
Learnt about alternators, regulators, brushes & their lamps, servicing my pa in Laws lorries (trucks). Mainly the Lucas 17ACR.
The voltage difference is important for illumination, but Duck, it is the current through the lamp (about 1/2 Amp) which is necessary. A LED will light with 10mA which is 1/50th of the maximum required level. The lamp also serves as a current limiter to prevent blowing the internal regulator. Hence my recommendation of a 30 Ohm resistor.
I should have written "the only reason it energises at all, is the residual magnetism in the rotor. If the bike was new & fitted with a LED charge lamp, it probably wouldn't ever start charging".
I have indeed succeeded at making a sound emitting diode, but cannot make it loud enough or repeatable so I can replace the horn.
_________________
Regards Tim,

Grey haired riders don't get that way by pure luck
1996 Guzzi Cali3 LAPD
1972 750 Commando
G6HRN
#485

[Flying Duck]

Just out of curiosity, what happens if the factory filament bulb goes out? Does the alternator not work?
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[Tim (Midland Section)]