Charging light behaviour

[FuelCooler]

Dan is right also check that the alternator is not puting out a/c voltage that will give you a heap of trouble. Make sure those grounds are good and tight.

 

Brent

 

If the alternator has an internal rectifier! Otherwise it will put out AC by design.

Just f'in with ya Brent.

Cheers,

Steve

[gstallons]

If the alternator has an internal rectifier! Otherwise it will put out AC by design.

Just f'in with ya Brent.

Cheers,

Steve

 

After hearing what you said about the 16v output you should take the alternator to a rebuilder. Have them to repair it and you'll be "good to go". The disconnecting of the wiring and battery is just a coincidence!

[belfastguzzi]

I took out the alternator this afternoon and put in a new regulator. Unfortunately the problem remains. It's still putting out 15+ volts, measured at the battery. I didn't check diodes or anything else when the alternator was out.

 

One more thing before I order a whole new alternator.

When the warning light bulb is removed, the output voltage stays low even when engine is revved. Does that signify anything or is it just what you would expect?

 

Dan, there isn't a "warning lamp control unit". That would have been older battery-excited models.

This is Lucas A115 - 45. As far as I can see, there will be a resistor connected across the bulb.

[Dan M]

Dan, there isn't a "warning lamp control unit". That would have been older battery-excited models.

This is Lucas A115 - 45. As far as I can see, there will be a resistor connected across the bulb.

 

Is it just running off of battery voltage with the bulb removed? I'm not familiar with that unit although many need to receive volatge from the warning bulb to operate. The resistor would be there in case the bulb fails. Often with older style units, if the regulator is not excited by the voltage through the bulb, it will not turn on. Tomorrow I will try to look for a diagram for that unit. Again, if the sense voltage is low (poor connection) the regulator will up voltage until satisfied. In other words, if you have a 1&1/2 volt drop between the battery and the terminal they use to sense the voltage level, the regulator will up the voltage from 14.5 to 16. Let me make sure this is how Lucas does it. Hopefully the US model uses the same set up, so wiring diagrams will be accurate. If I can't find a wiring diagram I'll call my rebuilder and see if he has any info on it.

You may want to check and see if all alternator terminals that are hot with the engine running match battery voltage. This still sounds like there is a voltage drop somewhere to me.

[belfastguzzi]

Is it just running off of battery voltage with the bulb removed? I'm not familiar with that unit although many need to receive volatge from the warning bulb to operate. The resistor would be there in case the bulb fails. Often with older style units, if the regulator is not excited by the voltage through the bulb, it will not turn on.

Cheers Dan

Yes, the ignition light resistor (in the LR wiring diagram) would be there to keep a feed if bulb blows – so what I don't understand then is why does removing the bulb give the result I'm seeing. Oh – I think that I see what you're saying now. You mean the voltage isn't rising, with the bulb out, because the alternator hasn't started to operate. So could that mean that the resistor wiring is broken? I'll have to investigate that. Running off the battery could be right, as the meter stayed fairly constant around 13.6V or so, from memory.

 

Hopefully the US model uses the same set up, so wiring diagrams will be accurate. If I can't find a wiring diagram I'll call my rebuilder and see if he has any info on it.

 

The Lucas model number is 24181A

A115 - 45

 

It also says 423612V (

[Dan M]

Cheers Dan

Yes, the ignition light resistor (in the LR wiring diagram) would be there to keep a feed if bulb blows – so what I don't understand then is why does removing the bulb give the result I'm seeing. Oh – I think that I see what you're saying now. You mean the voltage isn't rising, with the bulb out, because the alternator hasn't started to operate. So could that mean that the resistor wiring is broken? I'll have to investigate that. Running off the battery could be right, as the meter stayed fairly constant around 13.6V or so, from memory.

 

The Lucas model number is 24181A

A115 - 45

 

It also says 423612V (

 

 

Can't find any relevant diagrams. Let's look at it another way. Are there a total of three wires connected to the unit not counting capacitors? If so, the large wire is the output, one small wire is from the indicator (bulb) and the other small is for the sense terminal. The large wire has battery voltage at all times; the indicator wire has voltage coming from the bulb, so check it with the unit unplugged and the key on; the other "sense" terminal should have full battery voltage with key on. Compare it to the battery both key on engine off and while running. The unit grounds through the case mounting bolts. If you have all of that and a good ground, feel confident about buying an alternator.

[belfastguzzi]

Thanks

Dan M, GS and all for useful advice.

 

I replaced the regulator at the time but it didn't make any difference. I've mostly kept the vehicle off the road since then, especially as I have a bike back on the road. But I'll need it in a couple of weeks, so I got a new alternator and fitted it this morning.

That's done the trick. Charging light is now behaving as it should and there's just over 14V charging the battery above idle.

That's one or two more things learned about the electrical system. Good stuff.