Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Rectifier.

Output is rated at 38A so is more bike-like than car if you are wanting to run accessories off the 12V supply.

Thanks Calum, that's higher than I thought. At least with bike style alternators you have easy access to external rectifier/regulator.

Just to continue the regulator-rectifier saga, mine packed up yesterday. A few minutes after putting on the headlamps for a bit of a thunderstorm I flicked the readout on to voltage to find only 12V so it was off with the lights and try to get home before darkness fell and/or I ran out of battery. This was duly achieved; got into the lock up with 9.7V showing.
My first regulator packed up at about 9000 miles and this second one, which was fitted at the factory has lasted for some 15000 miles. This second unit has always been fitted side on, on the chassis brackets rather than the earlier face on, engine mounted brackets and its always had the second earth point.
The way it was mounted was by direct bolting to a (rusty!) steel plate which is in turn attached to a larger bracket plate via three rubber bobbins, this bracket plate is in turn bolted to two brackets welded to the chassis tubes.
What I found on dismantling all this was that the shape of the plate bolted directly to the original regulator had pushed the earth and positive cables into tight bends just where they exit the back of the unit and the insulation had failed on both cables leaving bare copper close to each other and tight against the steel plate. Presumably when the rain came on there was enough of a short to finally kill the rectifier.
Have now fitted the eBay special regulator-rectifier that I've had lying around for about the last three years and with a quick boost from a recently acquired lithium booster pack normal service has been resumed.
I've long suspected that the many failures are not just due to the standard unit being inherently rubbish but are in large part down to chaffing of the positive cable's insulation leading to incipient short circuiting and in due course the total failures that we know so well.

The dead black box attached to the rusty plate;


The back side of the dead black box and rusty plate;


Close up of the back side of the dead black box and rusty plate showing the bare copper;


"New" regulator-rectifier mounted with spacers directly to the larger bracket plate;


and again;


Camera phone photos so not super high quality.

I still have the original electrical control despite a short circuit to ground which emptied the batterrie 4 days after the acquisition of the mtw since I changed completely all electrical faisseau with fasteners and no problems yet, all the frame fixings mass clean and secure with aluminum grease and replace the electrical faisseau sheath in some places.

Electrical cycle normally provides quality equipment, I have a nine-HD adaptable alternative to solve for problems.

Here's another electrical fail waiting to happen - the oil pres. sender wire sheath had pulled free from the plug (shown unplugged) The wire was hanging in the breeze by the 2 very fine wires inside. I taped it up as best I could with 3M #33 electrical tape to reinforce it. This is just behind the oil filter. The big plug shown, I believe, are the rectifier leads and are now secured to the frame with a zip tie. Per this thread I will need to check the wires for chaffing.

Yellow for Ohlins 😊😊😊

I also moved my rectifier to the frame when i replaced
the stock unit for a Harley Davidson unit.

Well known fact; yellow springs are faster! Ask any biker.

I pulled the rectifier off & found one mount had sheared. The insulation looked good, did not see any bare wire as Calum's photo. Disconnected the connector by the oil filter but 2 other wires go up to under the cowl either side at the front so remade those as well. Also pulled the plugs on the front lamps & found no bare wire. Remade the earth connection behind the rectifier.
On restarting voltage was 14.3 even at idle with head lamps on. My joy did not last long dropping back to 13.8V headlamps on & 14.4 on side lamps.
So I'm thinking maybe a failing rectifier. What Harley unit fits & do they have all the correct connectors including earths & the 2 wires up under cowl? If not do I need to buy connectors to solder on?

Tim

The HD part number is 74540-01, the multi pin connector is the same as the M3W, the B post lead needs a larger eye terminal crimping on. Apart from that a straight swop, I bolted mine on without bobbins.

Tim, I think your voltage is pretty normal. The old standard used to be for cars) 13.8 to 14.2. I wouldn't do much on your car at the moment, just keep your eye on it.