G generator light on when engine running

[piggy]

Hi
I don't know if anyone can help but I stupidly connected a battery the wrong way round on the van today when fitting it. Instant sparks and I disconnected it realising what I'd done.

I connected it the right way after feeling like a right idiot and the engine started but now the generator light (im running dynamo) lights up when you turn ignition on but will not go out when engine is running. Light is off when engine and ignition are off.

Thanks in advance


James

 

[sparkywig]

If you're running a dynamo it may need repolarising.

 

[piggy]

Hi Sparkywig
Thanks for that. I am running a dynamo. Would I need to do that even if I hadn't turned ignition on when connected battery wrong way?

I've measured my charging rate today to see if it's charging and I only get 12.28V which rises to 12.3V when I fast idle. Doesn't go higher.



James

 

[slow-lane-Matt]

If you look on youtube you'll find videos showing how to test the generator (remove the cables and measure the voltage on the generator's terminals which should move between 20/50v when reving.)

With cables connected this 20/50v is sent to regulator which feeds back signal to generator via 3rd skinny cable which reduces the voltage back to the expected 13.8V to charge battery

...So from what you are saying I would suspect the regulator could be bust, so generator current/voltage not getting to battery.

The .02V difference you are seeing is probably "noise" and in any event not enough difference to effectively charge battery

So I guess your battery is not charging - don't get stranded....!

 

[piggy]

Thanks Matt,
I went down a bit of a rabbit hole on You Tube looking at some Moss videos which were useless for the VW but found some other ones and did the test above that you mention. I also worked through the following link http://www.vw-resource.com/generator.html#maximum - Running the generator as a motor (briefly) by disconnecting from the car and then running +ve and -ve to a battery, connecting the field terminal to -ve on the generator made it run faster. Reconnected it and we are now generating 12V at idle. High revs and it blipped to 80V although I suspect this might be the voltmeter. Reconnected to the regulator and it is running at 12.5-13V at idle then up to 14V at high rpm.

So in summary I think the only damage I have done is reverse the field polarity on the generator.

Thanks for all the help
James