test dynamo

[Tumbleweed]

HI FOLKS ,    I have removed said dynamo and tried it on the drill again ,  a two speed drill  gives 4v  at 900rpm  and 14v at 2400rpm  how fast will the dynamo spin at medium revs on the bike because I get under 1v revving the engine slightly  TW

[trevinoz]

Do you have a good contact between the generator body and the crankcase?

[Tumbleweed]

hi, Trevinoz  I am going to put it back on the bike sometime to day and I will make sure that is so .   thanks  TW

[bsa-bill]

how fast will the dynamo spin at medium revs on the bike because I get under 1v revving the engine slightly

Belt drives increase the speed of the dynamo, beneficial at low revs

[duTch]

 

hi folks ,   well I fitted  it to the bike and I don't even get 1 volt direct from dynamo      also I  flashed the F terminal for polarity ,  the D terminal flashes as well  is this normal ?   TW

 I've always been of the notion that 'D' & 'F' have to be connected together from the desired battery terminal to 'flash' for polarity 

[bsa-bill]

I've always been of the notion that 'D' & 'F' have to be connected together from the desired battery terminal to 'flash' for polarity 

need to be connected together to get correct voltage from dynamo, then flash the F field terminal.

[trevinoz]

It'll flash the field either way.

[bsa-bill]

need to be connected together to get correct voltage from dynamo, then flash the F field terminal.

OOPS that doesn't read as I had intended.

I meant they have to be connected together to get the correct voltage, they don't need to be connected to Flash the dynamo Field

[Tumbleweed]

hi again everybody ,  I cant even get 1v at revving the engine now ive fitted it back on , even ran earth separately still no luck but 2300 revs on the drill I get 14v and lights up a 12v bulb brightly       TW

[groily]

Are you 100% sure you have it set to go the right way? Sounds as if possibly not (or at least, what you are seeing would not be inconsistent with that.) Just a thought. . .

[Tumbleweed]

almost certain Groily,   ive ordered a new set of brushes I will try that , if that don't work I will take it off again and check what you have suggested , although I did run it with the drill anticlockwise when I got the best result . I  wonder what  rpm the dynamo is doing at 30 mph for example.     TW   

[groily]

Hmm  . . . anti-clock is right, certainly, so  . . . dunno!
 
But  . . . if it delivers the voltages you described, and also supports loads when run up on the bench, the darn thing should work on the machine.
What happens if you stuff a meter between the dyn's joined F and D terminals (loom disconnected) and a good earth with the engine running? Loadsa volts? . . . or is that how you obtained the miserable 1v you mention? Loads is good, one measly volt isn't.
If there are loads, what do you then see (loom reconnected) if you stick the meter between the A lead from your regulator (to ammeter, switch etc) and earth, with the engine running? Should see rising volts, settling to steady-ish charging voltage at higher rpm. Or, across the battery terminals with the engine running?

At 30 mph the dynamo will be turning - I'm guessing due to a few variables - in the region of 1700-2200rpm, depending on gearing of the bike and the drive you have on the dynamo. A bit faster than the engine is turning, anyway and well above kick-in speed, but maybe not enough to support serious loads. Mine shows a small charge with lights off at that speed in top on fairly standard gearing (it's minimum snatch-free top gear territory though), but needs a few more revs to balance headlight etc (at 12v).

[Tumbleweed]

the way ive been testing it is F &G joined together on the neg on the multimeter and pos to earth ,    and not connected to the loom and   direct to the dynamo, I will see what happens when the brushes arrive and check  rotation  .         thanks  TW

[bsa-bill]

F &G joined together 

Typo ?

[Tumbleweed]

F&D  sorry.