2013: warning light and battery symbol

kwack

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Ride daily, newish battery 6m old

Riding home today and the red warning light came on along with a battery symbol

I have checked the battery voltage and its around 12.5 not started. When starting it drops to around 12

Assume its the alternator belt so have read a few forums and watched a few videos but they all seem to be on non lc bikes and have a plastic cover on the crank cover

I dont have this on my bike its just the crank cover in metal. Can I just take this off and it will be the same underneath. I don't fancy pulling it off and loads of oil comes out

Also any tips to replace or anything else I should be checking?

Thanks
Kwack
 
There is no alternator belt,unfortunately for you if it's not the reg/rectifier or a wiring fault the early liquid cooled bikes were prone to the odd alternator failure. Alternator is inside the engine and very expensive to replace, here's hoping you have a warranty.

Sent from my SM-A202F using Tapatalk
 
malcopopolo said:
Check basics 1st - could be a faulty battery!
Click to expand...

I have left it on charge overnight and have a spare battery that will try first

Found a great write up on how to test the battery, regulator and alternator. Will give that a go over weekend

Thanks
 
According to the Riders manual, the fault OP describes has the following text: Battery charge voltage insufficient


This means that the alternator is not charging the battery. This is also confirmed by the voltage reading after the engine is started.

Let's hope for a faulty regulator, as it is a cheaper fix than the other alternative, a faulty alternator.

These are the two options to choose from.

It has nothing to do with a faulty battery.
 
The alternator on an LC is not an alternator in the std sense

Is a flat disc alternator and resides where the clutch used to be on the hexhead models - ie the back of the engine

Unfortunately the engine has to be dropped and split to get at the alternator, unlike the hexheads where the gearbox could be removed

from the bike with the engine is situ
 
Second thing that you need to do after testing the battery voltage is to check the system (battery) voltage with the engine running.
 
knutk said:
According to the Riders manual, the fault OP describes has the following text: Battery charge voltage insufficient


This means that the alternator is not charging the battery. This is also confirmed by the voltage reading after the engine is started.

Let's hope for a faulty regulator, as it is a cheaper fix than the other alternative, a faulty alternator.

These are the two options to choose from.

It has nothing to do with a faulty battery.
Click to expand...

So a battery that that is drawing more current than the alternator can provide will not reduce the output voltage?

Batteries resistance can increase... Most likely it is not the battery but for what it costs it is an easy test.
 
Hi

Quick update. I downloaded a document off the internet which explained in some detail all the checks I needed to do from battery to rectifier etc

Battery seems fine
Rectifier off bike tested all fine
I then started the bike with the grey plug pulled out and did some tests then. The vac was like similar on two but very different on one of the last tests

It read like 0.60 on connectors 1&2,1&3 but when I tested 2&3 it was like 0.15

Could this be a short in the wire and if so what panels doni need to take off to chase it back or does this point to a failed stator?

Thanks
Kwack
 
malcopopolo said:
So a battery that that is drawing more current than the alternator can provide will not reduce the output voltage?

Batteries resistance can increase... Most likely it is not the battery but for what it costs it is an easy test.
Click to expand...

If the battery is that bad it will not have the power to start the engine. OP is able to start the engine from the battery.
 
You still need to check the system voltage with the engine running.
 
BobT said:
You still need to check the system voltage with the engine running.
Click to expand...

Quote from Op's initial post
".....
I have checked the battery voltage and its around 12.5 not started. When starting it drops to around 12"
 
kwack said:
Hi

Quick update. I downloaded a document off the internet which explained in some detail all the checks I needed to do from battery to rectifier etc

Battery seems fine
Rectifier off bike tested all fine
I then started the bike with the grey plug pulled out and did some tests then. The vac was like similar on two but very different on one of the last tests

It read like 0.60 on connectors 1&2,1&3 but when I tested 2&3 it was like 0.15

Could this be a short in the wire and if so what panels doni need to take off to chase it back or does this point to a failed stator?

Thanks
Kwack
Click to expand...

Unfortunately, the wires in the plug goes the shortest way to the stator.. While a shorted cable in theory is doable, it qiute frankly is not very likely.
Another way of checking the output from the generator is to measure the voltage over the open connector while the engine is running.

Set the multimeter to measure AC. I have not been able to find a specified voltage specified from BMW, they merely refer to the diagnostic system. However, generally speaking, a typical voltage would be in the range of 50 to 80 V AC from each of the coils in the stator. Whatever the voltage may be, it should be a similar reading from all three phases.
 
kwack said:
I then started the bike with the grey plug pulled out and did some tests then. The vac was like similar on two but very different on one of the last tests

It read like 0.60 on connectors 1&2,1&3 but when I tested 2&3 it was like 0.15
Click to expand...

Those are not VAC readings they look more like resistance.
Are you sure you had the multimeter set to `VAC` with the engine running?

If they are (accurate) resistance readings of the three phases in the stator (alternator) the one at .15 Ohm could indicate a shorted winding. Not good..
 
See document link post 13 of the electrical problem thread.
 
kwack said:
I have checked the battery voltage and its around 12.5 not started. When starting it drops to around 12

Kwack
Click to expand...

Hey Kwack,

I’m not quite clear about this test.

Just to confirm, did you test the voltage across the batt with the engine running?
Then raise the revs a little to see if it changes?

I’m not sure if you meant the 12v was the drop when the starter was turning the engine or when it was idling or revving a little.

Good Luck


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