Is there any way I can check if the magnetism of the Lucas rotor is up to scratch?
The bike ("61 ES2) only starts charging with no lights on, at high revs, the battery will soon go flat in town riding.
I suspect the rotor. Besides establishing if it is satisfactory, is it possible to re-magnetize it?
From what I've read on the internet, it is a difficult process requiring special equipment.
Hi Richard, A rough test is to see if the magnetism is strong enough to hold its own weight. I would suspect a stator coil is out or switch contact or bad bullet connections from the stator under the battery box . If it really is the rotor I can flog you a spare one .
From what I’ve been told in the past, you should be able to use a screwdriver to pick up the rotor by just the magnetism in the rotor. (In other words, the magnetism in the rotor is strong enough to stop it from dropping off the screwdriver when it’s lifted up).
Hope that helps
Thank you both, this is just the information I need.
I'll test it tomorrow.
I hope I don't need to re-magnetize it - probably easier to get a replacement.
My rotor does indeed stay attached to the screwdriver - when attached on the circumference on one of the magnet poles; it does not stay on when attached to the flat end surface of the rotor.
It looks like my problem is elsewhere.
Thank you for your help.
Does anyone know how the stator coils are wired - ie, which direction (clockwise or anti-clockwise), what size wire, how many turns, connection sequence of coils?
You need to check the magnetism on all 6 magnets and the rotor must support its own weight on the spanner or screwdriver you hold out for it. I know the basic of the stater coils winding but knowing, direction size of wire and connection sequence will only help you if you can wind the coils yourself-I do NOT know of any company or person in the UK with the knowledge to do this job economically-if you do let me know as I have some work for him. IF you must sort out the coils your self then measure the stater you got, the direction of winding can be seen, the wires size can be measured, counting the number of turns would be a hard job so just wind it till it is the same size as the others. Interconnection between the coils is also easy enough-just look at it and follow the wires. The 6 coils are in series pairs, one pair being low output (trickle charging ignition only) further 4 coils come into play when head lights are on. No mention here that rectifier is in good order?
Further facts-as it is a 61 ES2 it could be 6V still, in which case you should have a stater of lowish output with a 70mm rotor. There is no more staters made for these rotors. A new stater would mean an RM19 3 wire (usable for 6V or 12V) (74mm rotor) Of course you will have to change the rotor as well. I also have a spare (for sale) 70mm rotor.
It is advisable to check the full output of the alternator before changing anything-details on aoservices.co.uk By the way Lucas Alternators on British motorcycles (permanent magnet types-do not have armatures.)
Thank you Al for the useful information you've given.
I think I mentioned previously, that the stator (ref number 47165A-1060, 70mmn rotor) has 4 lv coils and 2 hv coils (many more finer wires).The person who rewound the stator for me did it as a favour as his company - here in South Africa - rebuilds large mine winder motors - but stupidly I did not ask him to do all 6 coils the same and he won't do it again.
So, the hv coils are not being used, and the output of the four lv coils is insufficient to charge the battery except at fairly high revs - even with no lights on. The fact that it does charge the 12V battery at all surely means it is a 12v stator. When the engine is running again - in a week or so - I will do a voltage test, both open circuit and connected to a bulb.
I would like to rewind the two hv coils to be approximately the same as the 4 lv coils and so hopefully get some more power out of it. You say the coils are in series pairs, but how are they paired - opposite each other or next to each other?
Your write-up will be most helpful, but is the direction of winding the coils (clockwise or anticlockwise) important? Unfortunately, the connections and winding direction cannot be seen as the rewinding has covered them up with tape and shellac (?). (Photo attached)
A new Wassell power module is being used.
Thank you for your help.
I have found the attached diagram on the web. I don't know if it applies to my situation though.
Although electric technology is not my field, it seems very clear and understandable to me.
Any comments, anybody?
The diagram you show regarding stater winding unfortunately won't help as this is for 3 phase. As far as this situation is concerned the pairing of the two hv coils will have to follow the pairing already in place for the 4 lv coils. I can see your need for the information now. What I can do is inspect one of my 'failed' stators. I will leave you to sort wire size and number of turns but I can possible ascertain phasing and connections/pairings. Please get in touch via my web site aoservices.co.uk
Thank you Al, I will do that.