Original 6v Dyno Unit

Hi all,

After a complete top to bottom rebuild I have finally got my 501 engine running this week on a little test bed that I have built – first time in over 40 years that it has run!  The jetting is way to rich (awaiting arrival of leaner pilot jet), it does not rev to well but it will idle.

My question is regarding the dyno unit which supposedly charges the battery – can someone explain how it operates, my understanding it that it kicks in when a certain RPM is achieved with the generated current closing the contacts and delivering power to the battery?

What would be the best way of testing and measuring if this part of the circuit actually works?

Thanks in advance

Steve