Lomax charging problems

[howardjs]

Hi again, Re a charging indicator.
Alterators must be suppied with an excitation voltage to get the rotor magnatized to make the machine produce an output voltage.
The original alternator fitted to 2CVs is a battery excited and so needs a rotor relay control unit. This is swtched on when the ignition switch is turned on and supplies the required excitation voltage to the alternator rotor. There is no indicator used. Some early Lucas machines were also of this type. Lucas added a 3AW warning light control unit (looks like a canister type flasher unit). It may be possible to use this with the 2CV alternator. It has 3 spade terminals AL goes to the alternator WL to a warning lamp the other side of which goes to the ingition switch. And E which goes to earth. When the ignition switch is turned on the light is on, as the alternator voltage increases a heater wire inside the unit expands and switches a pair of contacts off and the light goes out.

All later Lucas alterators are self exited. All the control circuits are electronic and housed inside the alternator itself. This type of alternator will start to produce a small output without battery help however an initial boost is provided by the battery via the 2.2W indicator lamp which is connected to the ignition switch. As soon as the alterator produces the full output the voltage at the indicator (IND) terminal will reach 12v and the light will go out. So, the light has two functions. (very clever)! So, another way to get a charge warning light is to change to a Lucas Alterator. In this case the original voltage regulator is removed. The one I used (and usually cheapest) is a Lucas A127 as used on a later Mini (not BMW).
What ever you do NEVER do anything with the alternator connections with the battery connected (or sparks will fly) and NEVER start the engine with the alternator disconnected (or sparks will never fly again)!!!

After all that you can do as Ken suggested and just fit a voltmeter. You wont get a nice red light to see go out but you will get a nice needle to watch showing a healthy 14 volts (Hopefully)!!!

See you this weekend?? Howard

[hotfoothowell]

My Lucas alternator has only the two terminals, so the fact that it is connected to an external voltage regulator suggests, from all the foregoing, that that is the correct set-up. However, measuring the voltage at the battery with engine off, and then running, shows a slight drop with the engine running. So it would appear that the system is not charging. I'd welcome suggestions as to how the alternator can be tested on the bench. Does it have a carbon brush pickup system as in early generators, in which case I assume the brushes can be replaced?
Patrick

[pulhamdown]

[quote="Ken Hanna"]Alternatively, fit a voltmeter, which will prove to be far more useful. Ken/quote]

Or, if you don't want another dial on your dashboard, you could fit one of these:
http://www.ebay.co.uk/itm/150479033981? ... 1497.l2649

I have one in my Pembleton, and find it excellent. There are six different modes ranging from under 11.8 volts to over 13.2, + one for overcharging. Green for healthy charge, and red for poorly. I've got nothing to do with the guy selling, and making them in Scotland, despite sharing the same surname. Just a very satisfied customer.

Colin

[howardjs]

Not sure which Lucas unit you have, anyway apart for the rectifiers there isn't much to go wrong. The stator and rotor windings are quite robust and don't usually burn out, if there is a problem here you can usually smell it. There are 2 slip rings with brushes which can wear down. They are replacable but I have never had to do it. Testing the diodes and stator windings means unsoldering the diode pack to test each one and to test the windings for continuity or a short to earth. I have done this after I blew an alternator up after forgetting to plug it in before starting the engine!!! This wiped out the diode pack. I found a replacement at an autojumble to get me going, it's still on the car!!...The most likely problem is either the diode rectifier pack or the seperate voltage regulator. Sorry I don't know of a more simple bench test. Howard

[hutchii]

Howard, I recall the use of a 3AW on a Transit I had years ago. It was fitted with a Lucas 10AC alternator if I remember correctly. I had problems with a battery progressively going flat which I eventually traced to the 3AW being missing! Nobody at the time could explain why without it the warning light behaved normally, ie it went out when the engine was running, and the battery would last for up to a month after a bench charge despite being used on largely short journeys. Presumably the alternator was retaining some magnetism? Never had any further problems once I fitted the 3AW.

The alternator on the special I'm currently building is a "short" Ducellier(130mm front to back) marked as 22/30A and 7532E L5. When spun by hand the bearings make a hell of a noise, perhaps because it's been stood idle for years, but I await with interest the answer regarding bench testing, before I decide whether to consider replacing the bearings.

Re Lucas 127 unit, I see on ebay that "127 series" is mentioned in a number of ads, and output quoted varies from 55ish to 70amps? Which one might I require and will it (they) fit without mods, either to the manifold or the alternator itself?
You're certainly right about the cost of a Lucas unit compared to a genuine 2CV replacement!

[david tocher]

This book will tell you more than you might wish to know about alternators, how they work and details of all shapes and sizes - download from

http://www.ebook3000.com/The-Twelve-Vol ... 20325.html

There's another book called the 12 volt bible which does everything from a very basic level
available here - don't be put off just because it mentions boats!

http://www.2shared.com/document/g_OhFhE ... ts_ed.html

David

[howardjs]

Regarding Lucas A127s they used to be made from 28A to 70A, as we don't have electric windows or heated bum pads etc a small one will be all that is needed I think mine is 30 or 35A.
If you want to calculate the current your car needs just make a complete list of everything that uses a voltage then write down the current each one consumes and add them all up, add about 10 amps for battery charging and that should be enough.
Unfortunately the lugs of the Lucas are different to the Ducellier so some adaptor brackets would be needed.

It always amazes me how the 2CV alterators last at all being fitted as they are directly to the exhaust manifold. Some of the specials I've seen have the alternator totally exposed and close to the road. If the car is used in winter the alterator must consume a fair ammount of salt on each journey. Salt, water and electrics don't get on well!!! Regarding the bearings, if you can hear them at all, sounds as though they are goosed.. I'd try the alterantor first to make sure it is electrically OK before you waste time on the bearings.

BTW Patrick, I just noticed that some Ducellier units are fitted with a replaceable fuse plate, maybe this is the original problem??
Howard

[Ken Hanna]

Howard,
when A series alternators are used with the original cowling, there's a healthy flow of air directed at them from that fan on the front of the crankshaft to keep them cool...
Perhaps there's a case for 'bare' engines which retain the original mounting to be fitted with an alternator which has the typical arrangement of a small fan behind the drive pulley?

Those small Ducelliers are very easy to strip down and rebuild with new bearings, however corrosion/pitting of the stator windings is their main enemy, as you've already pointed out.
The stator wires can be disconnected at the junction plate near the fuse, then a continuity check carried out.
There should be no problem with their rated output as regards the total draw on a Lomax even with 60/55 watt headlamp bulbs, although I'd advise against the 100/80 watt variety.

Ken
p.s. Hasn't Patrick got a Lucas alternator ( as well as a Ducellier VR )

[howardjs]

yeps that's right it's a Lucas not a Ducellier..sorry Patrick back to the drawing board..

[hotfoothowell]

After having my alternator bench-tested, and found to be OK, I had the sealed Ducellier voltage regulator apart, and cleaned the points and ground plane, and bingo! A little alarmed, however, at a constant 15 volts charge - should it be this high, and if not, does this suggest that the cut-out is faulty/ needs adjustment?