Technical Battery light comes on after 10 min running ?

[rmribeiro]

Hi,

I have a weird problem. My Fiat 500 is running perfectly but after 10 min running the battery light comes on and stays on ( mostly ).

I tried to put a multimeter on the Dynamo and could not get a reading as it was unstable and ranging from 0v to maybe 20v - had to tell has the multimeter would not fix and just flash different values.

I did the same at the battery and had the same reading.

It looks like the Dynamo is outputting AC?

The regulator might also be at fault but it looks new and worked well for at least 2000 KM.

What should I do to diagnose the origin of the problem ?

 

[Bleeding Knuckles]

Hi,

I have a weird problem. My Fiat 500 is running perfectly but after 10 min running the battery light comes on and stays on ( mostly ).

I tried to put a multimeter on the Dynamo and could not get a reading as it was unstable and ranging from 0v to maybe 20v - had to tell has the multimeter would not fix and just flash different values.

I did the same at the battery and had the same reading.

It looks like the Dynamo is outputting AC?

The regulator might also be at fault but it looks new and worked well for at least 2000 KM.

What should I do to diagnose the origin of the problem ?

Hi, First you must check and confirm the output from the generator and compare the findings against a manual. Then check the output at the regulator. It does sound as if the output from the generator is suspect, check for worn parts (in the brushes and commutator) with a known good multimeter. If in doubt have the generator overhauled.
Ian.

 

[rmribeiro]

Thank you for your reply. My guess is that one of the brushes is not making contact and as such the output would have gaps and that would make the multimeter fail reading.
I will have to open the dynamo to check this.

I am not sure if it makes sense for the problem to only become permanent after 10 min of running.

The multimeter seems to be working correctly in every other read that I have done.

 

[Goldnrust]

Heat is what's likely to be different after 10 mins of running. I've certainly heard of damaged condensers and coils that stop working 10-20 mins into a journey.

Could it be that the regulator electronics aren't working right once they get warm? Or that one of the brushes is sticks when it gets hot?

 

[rmribeiro]

I will try to open the Dynamo and to see the brushes.

It might be that one is stuck and that could make the output non DC because while it is rotating you get 1, 0 , 1, 0 .

 

[rmribeiro]

Took the car to an Auto Electrical shop and it looks like it was more than the brushes. The Coils had to be rebuilt. Waiting for the rebuild process to be finished.

 

[rmribeiro]

Got it back. It was the coils. Now it charges perfectly.