Is gen light required? K1100RS

[ChristSFP]

When I removed the original dashboard, I´ve installed a Acewell and since the original gen light uses + and - for separate light I´ve tried to replicate it by using the + for the ace well light and - for a separate external diod.. Since the fuel tank is removed for the time being I can't try the charging capacity =/

My question is.. do I need the gen light to have the bike charge the battery when the bike is running or will this work anyway? Don't know if the resistance in the diod / ace well will even remotely emulate the OEM resistance.. I´ve just tried to replicate the light.

[rbm]

Yes, you will need a light or a resistor to emulate the charge indicator.  If it is missing, the alternator may work but most likely will not work, your battery will go flat and you'll be stranded.

Use a 50 Ohm, 10 Watt resistor inline with the blue wire going to the alternator.  the other end of the resistor connects to switched +12V.

Alternatively, wire a LED, not a signal diode, in place of the resistor.  Anode will be connected to switched +12V and cathode to the blue wire.

Post a schematic diagram of what you're trying to hookup using the Acewell and diode.  this will help us to visualize the circuit and see if it is correct.

[ChristSFP]

Super, thanks, will post a schematic. I´m basically trying to remove the original light, dont care for the function at all but I had it somewhere in the back of my head, that is was needed, so then I tried to emulate it with LED indicators, one from the original light in the Acewell and another from a external diod I had lying around the garage..

[ChristSFP]

But what you are saying, get a 50 ohm, 10watt resistor, connect one side to the blue cable and the other end to blue/black?

[rbm]

This guidance recommends two 56 Ohm 2 Watt resistors. Other recommendations I've seen recommends one 50 ohm 10 watt resistor.  The choice is not critical, but I'd probably use the above circuit with slightly larger 4 watt resistors.

If you use the LED in the Acewell, then you still have the question of how is that LED connected internally within the instrument and will it function properly to give the exciter current needed to start the alternator working.  You're taking a chance it won't work. 

[ChristSFP]

Ok, can´t understand the german text above, but I made a quick schematic over what Im trying to do..

So main goal, remove the charge light all together but still have the battery charge while the bike is running.

[rbm]

Your circuit is not going to work.  Try this circuit:



On the left, "ign+" is the switched 12 volts; in the German diagram, it shows Pin 6 of the instrument cluster.
Next to the right is a diode.  This is optional and can be eliminated if you desire.
Next is the resistor. 2W-5W is probably large enough. 10W is over-design.
Last on the right is the blue wire leading to the alternator.

[ChristSFP]

Ok.. sorry, Im a newbe when working on this precise resistors.. so please bare with me.



Would the above work? And what do I do with the ground (brown) cables? Do I just ignore them?

[ChristSFP]

Or is it option B (below)?

[Bfbob]

The closest emulation of the 3W charging light bulb is a resistor that will draw 3 watts.  Using the formula W = V squared / R,  Call V 13 volts for good measure.  3=169 / 56.  So, as previously said, a 56 Ohm resistor rated at least 3 Watts is called for.  The closest you'll find easily is 50 Ohms, 5 Watts.  Just wire it in the same place the charging light was, and it'll work fine.  A 10 Watt resistor might not fit where you want it, but a 5 Watt is not much bigger than the light bulb and socket. 

Note:  the power rating of a resistor is how much power it is capable of handling.  How much it actually draws is determined by its resistance and the applied volatage.  Using a higher power rating will make it last longer;  like a light bulb, it will eventually burn out - but not nearly as soon!

[ChristSFP]

Thanks Bfbob! That answer really cleared it up for me

[diesis]

This is an excellent thread - thanks to all for the good descriptions.  I'll be putting the resistor in as described by rbm.

Two quick questions (if anyone is still checking this thread)

1) Is there a concern with the heat generation from the resistor if it is mounted in with the remainder of the relays on the k-bike?

2) I'm curious as to why this is necessary.  I understand why the charge lamp lights when the alternator isn't working, but not why it has to be there in the first place for charging to occur.

[dedmonston]

Same problem here, thanks for the posts!  I had taken off my instrument cluster and just tucked the wires away not knowing you needed the light in order for the alternator to charge!


Just took the blue wire and the green/black stripe wire and soldered them across the original light to verify it fixed the problem, and sure enough it did.  (I have a 1989 K100rs) so the pins were 6(green/black wire) and 9(blue wire) per the German diagram.


Now I just need to either do the resistor like in this post, or relocate this light and make it a more permanent solution...

[enb54]

2) I'm curious as to why this is necessary.  I understand why the charge lamp lights when the alternator isn't working, but not why it has to be there in the first place for charging to occur.

This light and associated wiring is used to apply a small current to the alternator field coil (called exciter current) when the ignition switch is "on" which is needed to initialize the alternator so that it will start charging when the engine is running. A quick search for "alternator exciter wiring" should satisfy and perhaps even exceed one's curiosity...