Testing dynamo output

[robin rose]

Hi guys, I want to test that there is output from my dynamo as I have no charge at the moment, wiring tests ok
so suspect the dynamo or regulator (electronic). Is it correct to connect the F and D on the dynamo then measure
with a multimeter to earth? Just want to make sure before I go and fry something. Rob.

[robin.parker]

Someone else will, no doubt, be along in no time with a detailed reply. As a rough and ready check, assuming the dynamo is off the bike, attach wires to the dynamo's F and D terminals, twist the other (bared) ends together and hold them on one battery terminal, hold the dynamo body against the other battery terminal (or use another wire) if the dynamo is good, it will "motor". None of this applies to the electronic Regulator,they are delicate, modern and mysterious and I don't understand them. Good luck, Robin.

[john.nash]

The top, sticky, topic in this sections contains everything you need to know:

http://forum.arielownersmcc.com/viewt ... ?f=8&t=189

"motoring"your dynamo may not prove it has output.

Baically you need to :

• leave it on the bike
• flash the field
• as you say, connect the F and D together and then take it to "earth"
• You will get over 10v quite quickly if you increase revs.

I find most problems are down to a dirty commutator.

[nevhunter]

I don't specifically want to contradict anything so far.
Generators can lose their residual magnetism, either by being pulled apart or in some cases just sitting idle for a while When this happens they will not "self excite" (unlike 6th grade schoolboys).
Depending on the internal wiring the regulator will earth the field or may use output voltage to regulate. (from the armature) The strength of the field current regulates the generator output..
IF you just apply battery voltage from the non frame earthed end of the battery to the armature terminal, with the bike running, it will magnetise itself, and charge straight away. This removes the need to vary the way you deal with the field terminal
A generator will work if there is continuity and no shorting in the windings, and if it is wired correctly internally.
The commutator, ( which is a rotating switch) must be true and should be undercut between the copper segments. The carbon brushes should have wear left and some tension on the commutator and not stick. Bearing play will cause poling (hitting the case) and affect the action of the brushes. According to Jo Lucas they were supposed to be serviced every 8,000 miles by returning to the factory Nev

[john.nash]

.... According to Jo Lucas they were supposed to be serviced every 8,000 miles by returning to the factory Nev

I wonder what wears at 8k miles ? Brushes ?
How long do armatures run for ? Do they have a finite life ?

[nevhunter]

Just wrote a long reply and lost it. I will have to summon up my reserves and do it again later. Nev