An ammeter is best for dynamo as it will show how much you are charging or discharging - very important with this set-up.
A voltmeter would be more useful with an ammeter, due to current output never being a problem, this instrument allowing you keep an eye on the battery's condition.
An ammeter will show instantly if there a charging fault, eg if you switch the headlights on and it shows a discharge instead of a small charge. Could be just a loose fan belt
Last edited by mike.perry on Fri Aug 02, 2013 8:28 pm, edited 1 time in total.