Alternator conversion. Pre engaged starter motor conversion. Questions

[Andrew]

Hello to you all. Sorry for the questions but I need some advice.

question one

how easy is is to convert from a Dynamo to an alternator not the actual mounting of it but the wiring bit, and has anyone fitted the dynalite unit that looks like a dynamo but is actually a alternator. 
question two

i am fitting a pre engaged starter motor with a solenoid mounted on the motor which is standard for this kind of unit. Do I still need the solenoid that is mounted on the car body as used for the old style starter motor.

thank you    

[JohnD]

Andrew,

You appreciate the difference between the two electrical generators?    Dynamo - DC, Alternator - AC.     The alternator's output has to be 'rectified' to DC for the car.   It has an internal circuit that does this, and also does the job of  the "Control Box" that a dynamo car has.    So while it's simple to bolt on an alternator, the Control Box must be removed and its connections revised, as must be the alternator connections.     There is an excellent and detailed account of how to do this whole job at http://www.mgb-stuff.org.uk/pdf/electricsapp1.pdf     That article is about an MGB, but they used exactly the same Lucas kit as Triumph!

The pre-engaged starter motor and the starter solenoid that you have already, use a "solenoid" for different purposes.      A "solenoid" is an electrical device, of a coil and a magnet, which moves the magnet forcefully when a current flows through the coil.      A starter solenoid is a very robust relay, that uses this  movement, initiated by the small current from the ignition key switch, to switch on the enormous (500Amp+!) current that flows though the starter motor, by pushing contacts between terminals attached to the starter cable.

The "Pre-engaged starter" (PES) is so-called because it uses its solenoid to throw the starter pinion into engagement with the flywheel, before the starter turns.     Only once it is engaged does another switch inside the PES allow current to flow through the starter motor (Contrast this with a "Inertia Drive starter" which I will leave you to look up!).      Some PES have a separate connection for a low current wire from the ignition switch, and have a battery cable that is permanently live, but you can simply adapt the PES to work as I describe, and retain your starter solenoid switch.   See: https://www.moss-europe.co.uk/media/pdf/GEU9405X_instructions.pdf

Good luck!

John

 

 

[A TR7 16V]

Further on the removal of the control box: The old housing is a good place for a fuse box. You can keep the external wiring as it is, and still add a number of fuses (I have 3 and a spare slot in mine):

 

Graham

 

[Pete Lewis]

3 hours ago, Andrew said:

how easy is is to convert from a Dynamo to an alternator

in every day terms 

at the contol box you co join all the 30 amp lucar wires terminals together 

you co join the  2 coloured 17amp lucar  wires  terminals together

that leaves the black control box black earth which you discard 

there can be an case for upping the wire size but as max load is unlikely to ever be used the existing dynamo

harness will work well 

Pete

[Andrew]

Thanks all for your help