Dynamo to Alternator conversion - Wiring

[Dexter_62]

Hi Guys
my latest project is to upgrade to an Alternator as i have had electric power steering added (brilliant!) and will add a stereo etc later on.

i have obtained an alternator based on a Bosch unit 70 amps from my local supplier where they managed to get one to take the double pulley from the Dynamo and get it all aligned. That's left me to fabricate some spacer tubes to mount to the original bracket.

Now the bit i'm struggling with is the wiring. i want to remove the old lucas regulator box and wire it to the new Alternators regulator which i understand is relatively easy, but i need to know which wires i link up and to where? it was also suggested that i run an additional wire from the alternator to the start solenoid as its generating a lot more amps than the old dynamo would have. Grateful to hear from anyone who's done this or knows how to do this.

thanks
Keith.

[piman]

Hello Keith,

the best way is to get a wiring diagram from a car that uses the alternator you have bought. It's not one I am familiar with, I assume it has it's own built in regulator. Most of the old regulator wiring can be removed but you will probably need the wire from the warning light and connect that to the alternator.

Other things that need looking at as there is a change of polarity, the battery leads may need to be replaced or remade due to the lengths of the cables. Swap the polarity of the coil, it will work as it is but the spark will be weaker. Check your fuel pump as it may have a diode for spark supression and that is polarity sensitive, I think you would need to buy a new diode (Burlen fuel services) for negative earth. The radio, if you use one will need changing for negative earth.

Alec
.

[Dexter_62]

Hi Alex,
thanks for this, i have already converted it to negative earth so that parts sorted (with the help of posts from the forum). What i need to know is which wires on the old regulator need to be connected up so that it works as you are right the new alternator has a built in regulator. The existing wires to the dynamo will attach to the alternator in the same way i understand, but i have seen mention that it would be advisable to run an additional wire from the alternator to the starter solenoid?

thanks
Keith

[BrianG]

Hello Keith,

As has been previously stated you don't need any of the wires from the existing regulator. You will need to keep the wire for the "charging/ignition" light on the dash but you may have to rewire one end of it either to ground or to ignition; the alternator looks like the output marked "D" is for this, but this depends on whether the D pin provides a 12V source for zero charge or expects to pull current through to lamp to ground. As alec says, best to check the wiring diagram for the car the alternator is designed for.

An extra (thick) wire from the alternator positive output (looks like it's marked "B") to the starter solenoid is a good idea as this will already have a thick cable to the battery (just don't bolt it on the starter motor side of the solenoid!). Also make sure you have a good thick braided strap from the engine to the body and from the alternator to the engine (looks as though it has a separate neg terminal rather than return through the alternator body).

[Dexter_62]

thanks guys, i will check the Wiring diagram as suggested.
Regards
Keith

[domedan]

Sorry, off topic but which electric power steering did you fit?

[Dexter_62]

Hi i got the system from Easysteer. The install took about a day and a half. Rick also fixed my turn signals so they turn themselves off now. i was impressed with his work and approach and would recommend him wholeheartedly. There was another chap who had his Mk2 done at the same time (well after mine!).
What i liked was you can adjust the feel as when we took it for a test drive it wasn't turned on. Then he turned it on and instead of going across the mini round about i was able to go around it! It has made it a pleasure to take out and my wife can enjoy driving the car too.

I have now installed the alternator which has fitted in a treat and works really well without costing a fortune for one of the kits from SnB etc.

regards
Keith

[domedan]

That's really interesting. I was looking at that, as I'm near Manchester anyway. I also like the fact that you can turn it off if required. Is it necessary to convert to an alternator if using this?

[Dexter_62]

No It runs with a Dynamo, but if you have everything on then it will struggle plus i wanted to put in a retro stereo for when we do trips so just making sure i'm not going to get catch out. I think its been a worthwhile upgrade and didn't take much to complete once i found a suitable alternator.

Yes you can turn it on and off, but its best left on once you have the setting where you want it! What i like is that if the system fails then it wont be any worse than without it, unlike a hydraulic system where you cant turn the wheel if it fails! Shame your not nearer as you could try it out. I have to say from my perspective i'm very happy with it as i can get the car in and out of the garage and drive without wrenching my arms etc. i found Rick to be very helpful. he makes sure that every that works still works and he was happy to address other bits i.e. my non canceling indicators.

[Dexter_62]

nearly forgot you would have to change it to negative earth for the steering!

[Doherto]

Sorry to hijack this post but i am converting to an alternator and neg earth to have the easysteer fitted in august, 10 weeks waiting list, i heard great things about it and have confidance in Rick who i went to meet before committing. However, and you will not believe this, i returned the posative earth dynamator to the supplier and they agreed a credit, against which i ordered two 65Amp Lucas alternators, one for a spare. They arrived today and i fitted one and there didnt seam to be any increase in battery voltage and no deflection on my Amp meter. I disconnected the alternator and tested for volts on the large pin output and there was nothing. I removed the faulty alternator and fitted the scond one. Without connecting it to the car i started the engine and again tested for volts on the output, nothing. The coincidence is too great to have had two faulty alternators delivered, so what am i missing. The alternator bodies are well earthed and there is no output from the ignition light connection. Without load should i get a voltage reading on the output when the system is rotating. I am totally baffled. If anyone has any thoughts i would appreciate them as i need knowledge before i speak to the supplier tomorrow.

[piman]

Hello Doherto,

running an alternator open circuit is not to be rcommended as it can over regulate and cause damage. Did you connect the warning lamp to the alternator as often they will not work without this input?

Alec

[Doherto]

Hi Alec, thank you for coming back so quick. I only ran without load for enough time to take the measurement and have tested the regulator since and its ok. No i did not connect the ignition lamp as the wiring is set up for the dynamator with a relay in line to switch the lamp on and off. I will run temp wiring to the new alternator in the morning and hope that does the trick. Will let you and others know what happens.

[piman]

Hello Doherto,

it's a while since I worked on dynamos so I don't quite remember the circuit. However the ignition warning light on an alter nator is fed live on one side and connected to the WL terminal on the other. It is that source of power that initiates the alternator output which is then self regulating.

Alec

[Doherto]

Hi Alec, and anyone else interested. Firstly i originally had a posative earth dynamator wired up, which is an alternator in a dynamo housing, but for some reason that circuit required a relay connected to the alternator to deilluminate the ignition light. Anyway, problem eventually solved with your advice and a few observations for info. I connected the new alternator direct to my battery with a lamp in series with a supply from the battery to the smaller connection. Great, the lamp illuminated but only dimmed when the engine started, also the battery voltage did not increase. To save everyone the three hours this took me to resolve, the main problem was that the fan belt was not tight enough, the alternator was spinning, with not too great a stress on the bearing but no output. When tightened it worked fine and the lamp went out and the battery charged. I then reconnected my car wiring with ignition lamp, without the relay, and amp meter. Charging was ok and the amp mmeter works but the ignition lamp stayed on? I have rewired my car and replaced all bulbs with led's which apparently do not operate in the same way as a bulb in an alternator circuit. I changed the led for a bulb and everything works great. Hopefully this will avoid anyone else experiancing the same issues. Thanks again Alec.