dynamo wiring question

H

harpmeister

Full member
Location
UK
I need to replace the wiring from the dynamo on my SF1, I was thinking of using either 2mm sq thinwall rated at 25amps or 3mm sq thinwall rated at 33amps, would either of these be suitable or is there something else I should be considering.

Thanks

Joe
 
Volt drop is usually the overriding consideration.  There's a useful calculator here -
http://www.12voltplanet.co.uk/cable-sizing-selection.html

You'll see 2mm2 is fine, given the 11A dynamo rating
 
Hello Breganze 750 electrics, dynamo and regulator system experts. I'm planning some work on a long term project SF that will involve replacement of the ND instruments and the dynamo charging indicator bulb there with a GPS speedo and electronic tach to eliminate mechanical speedo and tacho drive cables so I'm thinking of using a separate pair of led bulbs for the neutral and generator charge lights either in a replacement larger headlamp shell or on an instrument and switch bracket.

It's not clear to me whether the charge light must flow current to get the dynamo started and hence whether I need to have a significant current flowing through it so perhaps would need a load resistor in parallel with the led bulb which will itself flow very little current.

Has anyone replaced the dynamo warning light bulb like this? From your experience, is it necessary that it have a low resistance to get the dynamo started? Does field coil current flow through the bulb or in parallel with the bulb? The bike is not currently running so I can't experiment with just taking out the bulb to see if charging still works OK without it. 

Thanks for anything you can share.
 
The dynamo is in no way reliant on the generator bulb circuit. However the generator bulb circuit can prevent the generator from working if it gives a lead to ground. I have no experience with LED bulbs in this regard but the standard 3w system is as simple as it gets. You can always simply try fitting one, it cannot damage anything. I really can't see the point, when you are anything above idle there is no power consumption from the charge light, and even at idle 3 watt is insignificant.
 
Have Motogadget clock on one of my twins, which has led warning lights. Generator light workd just good as the old regular bulb.
 
Tippie said:
The dynamo is in no way reliant on the generator bulb circuit. However the generator bulb circuit can prevent the generator from working if it gives a lead to ground. I have no experience with LED bulbs in this regard but the standard 3w system is as simple as it gets. You can always simply try fitting one, it cannot damage anything. I really can't see the point, when you are anything above idle there is no power consumption from the charge light, and even at idle 3 watt is insignificant.
Click to expand...

I doubt this is helpful ... but a dynamo should not need excitation (however a gen. might depending on the wiring). An alternator .. yes. An old (1931) Chrysler motor I've had could be energised by briefly, manually closing the output relay to 'rebuild' the field windings.

Disclaimer - I know nothing about SF's.

Don't forget that LEDS can be polarised (works one way and not the other).
 
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