dynamo

[thadave]

hi all

i have recently fitted a new battery and dynamo after the battery was tested and found to be faulty .i fitted the dynamo as the battery was still not taking a charge.i also have a new regulator but havent fitted it yet.what voltage should i get off each of the dynamo terminals to negative as it still isnt charging.At the battery terminals its still only 12v which is 2v lower than it should be for a charging battery.any ideas.

best regards  dave

[piman]

Hello Dave,

if the dynamo is new then the next step is to replace the regulator. You should have 13.5 to 14 volts on the large dynamo terminal but the smaller (field) terminal will vary depending on the regulator.
If the dynamo is new old stock, it is worth flashing the field to see if it starts to charge? To do this disconnect the wire from the dynamo F terminal (small connection) and with a temporary piece of wire from the battery negative terminal, touch the F terminal on the dynamo a couple of times, you should see a small spark.

Alec

[thadave]

thanks for replying not sure what you mean exactly take the connection off the small terminal of the dynamo ,get one end of the piece of wire on the negative battery terminal  and put the other end where? on the small terminal or the dynamo housing or between the small terminal and the dynamo housing not the negative battery terminal.sorry for being a bit simple.at the moment with every thing connected i am only getting 12.3v across the battery and 7v between the large dynamo terminal and the battery negative and 7v between the small terminal and battery negative .the new regulator is the wrong one so i cant put it in yet.  tempted just to buy an electronic ignition and bypass all the regulator etc but if the dynamo is at fault it  still wont work.
input gratefully recieved
best regards  dave

[piman]

Hello Dave,

yes, just touch the small terminal with your bit of wire two or three times, this puts some current throgh the field winding and magnetises it slightly.

Alec