The Fordson Tractor Pages Forum

2 years ago on advice from local garage, I fitted a new dynamo. Previous dynamo was not charging the battery. Have checked connections, fan belt tension etc. but I am still having to put the battery on a charger every now and then, which makes me think there is still something not right. I have seen the notes about flashing the dynamo, I did not do this. Could it be that which I need to do to make the dynamo charge up the battery ?

Just remembered to say it's positive earth

Brian Cox wrote:Just remembered to say it's positive earth

First off Check the dynamo voltage output when the engine is doing say 1500rpm. Its should be at least 14.5Volts.

The dynamo flashing procedure is there to 'magnetise' the dynamo iron core.

As a result of this, the dynamo when first turning works as a permanent magnet generator and creates some volts (although little power), this voltage is enough to close the field contacts in the regulator and apply a current to the dynamo field winding and the generation starts.

So its easy to tell if the dynamo requires flashing as the regulator will not kick in

Hi Russelm, pardon my ignorance but how can you tell if the regulator has done it's bit

sorry, I'm gone till Monday night now, be back on then

Does the warning light come on before you start then go off once the engine is running? if so the dynamo must be generating something. For a crude check as to whether it is charging or not, just pull the output wire off the dynamo when the engine is running at say 1500rpm, you should see a spark. Another option would be to switch the headlights on, they should be brighten up when you increase the revs from tick over.

Hope that helps

Ian

Went and purchased a tester tonight, will test for charging tomorrow