Dear All, I've a 1998 ST2 which has a habit of destroying regulators , four so far with the Electrex RR50 lasting the longest at 3 year. New Electrex RR50 and battery fitted :- with the engine running at 3,000 revs. and lights on or off it runs hot, I’d estimate over 60 deg. C. Voltage across the battery at low revs. around 14, lights on or off, but at 3k. ramps up to 16 with near 20 with lights off, no ST2 components at excessive temperature. The battery voltage of my 900 Supersport is between 13 and 15 under the same cycle as above with the regulator temperature substantially lower than the RR50, same battery being swapped between the two. With the engine running and regulator - alternator disconnected the alternator output measures between 30 to 80V. A.C., same for ST2 and 99SS. All voltages measured with two Avo 8V meters which I’ve had from new, identical readings in both. If I continue as is the new RR50 will have a very limited working life. Perhaps the answer would be to replace the 420W. alternator with the 350 unit of the 900SS however that seems like treating the symptom rather than the cause. Any help would be very much appreciated, thanks Lads.
..so many things to cover.. I hope others beat me to it tbh. Firstly:- are your regulator plugs/connectors and alternator connectors in good condition with no signs of corrosion or melting/overheating/discolouration? Are the yellow alternator wires straight and "yellow" rather than wriggly and "burnt/dark" yellow? I can't speak for the current (npi) range, but was not impressed with Electrex replacement for my Cagiva Elefant around 10 years ago. Not only did it run hotter than the std unit i was intending to replace, but the output was less. I sent it back for a refund on these grounds which they reluctantly gave me. If you carry out a "search" of Forum posts, you will come across many threads outlining the replacement of your std unit with a Shindengen FH020/FH012 etc which, even when bought secondhand is a good, robust alternative although your loom needs a slight alteration to suit. BEWARE of (Shindengen Mosfet) imitations though.
hi the ducati type reg rec are shunt type they dump extra volts to ground i fitted a reg rec off a jap bike as they are a mosfet type which controls volts from the stator to 14,5v upgrade The wires from stator to reg rec starter motor battery then strip any wire you have removed it will be black burnt lots current passing along it found this seems like you’re referring to a regulator/rectifier for your motorcycle. Let me provide some information on this topic. The Shindengen FH020aa is a MOSFET-style regulator/rectifier, which is an upgrade from the older-style shunt-type units. Here are some key points: MOSFET vs. Shunt Regulators: MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) regulators are more efficient and stable than shunt regulators. They handle higher current and voltage better, making them ideal for motorcycles. MOSFET regulators are commonly found on new
I’d suggest checking the connections especially earth to the RR (assuming there is an earth connection, I don’t have my wiring diagram to hand atm) - if the earth is faulty then it can’t pull the voltage down. Might be worth running a new earth lead in case it’s a corroded connector
My 916SPS 1998 burned the regulator too, a common problem at the time. I replaced it with a Shindengen as mentioned above. Highly recommended. A fully charged lead-acid battery should never be charged with a voltage over 14,4 Volts. Above that explosive gas is being generated in the battery, and it could lead to an explosion.
IIRC? The ST2's alternator rotor was a rare earth magnet type, that put out a lot more power than earlier type rotors. The ST2's had a specific reg/rec to cope with this, normal Ducati reg/rec's from the rest of the model range lasted a very short time if fitted to a ST2. IMO your best bet is to fit a Shindengeng MOSFET. Steve R
MOSFET is the way to go. But in the immediate short term as said check connections etc. Keep your lights on as this will help use up excess energy, also if you have led lights their super efficiency will make the problem worse.
Dear All, Many thanks for all the replies on this topic. The wiring and spade connectors from the stator show no sign of distress, wiring colour clear yellow and flexible and no verdigris, etc., on the terminals, similar applies to the wiring harness from the regulator output. I was considering changing the stator for the lower output 900SS version but will leave that option for the next iteration. The Electrex RR50 is MoSfet based however I've added a 10mm x 110 x 80 aluminium plate to the resin side of the unit to act as an additional heat sink with slots cut in the fairing cheek piece to maximise airflow. The effectiveness, or otherwise, of this will be revealed with time. The bike's owner has been advised to run with the lights on and consider the fitting of heated grips from Oxford Products. Incidentally when attending the 1998 W.D.W. I saw first hand the result of a failed 916 regulator. Returning to the Misano camp site after a tour of San Marino and Rimini on the push bike I came across a group of parked up Ducati mounted Germans with smoke billowing merrily from one 916 whilst the owner was frantically searching the back pack for a spanner to undo the battery terminals. Not wishing to see the total demise of the bike I grabbed the damn hot +ve cable and with quick twist of wrist broke it clear of the battery, one bike saved only requiring a replacement regulator and battery terminal. On return home I brazed a washer to the battery screw and slotted the cable terminals, now with a gloved hand I can slacken the retaining screw one turn and pull the cables clear double quick. Also relocated the regulator to be directly inline with the lower fairing "NASCAR" duct with a large aluminium plate to shield from the front exhaust. The 1997 916 SPS still fitted with the original regulator to this day. Thanks again all with a special mention of Sir Tim Berners-Lee, the instigator of this forum's communication medium.
Well, it seems the Electrex RR50 with added heat sink and fairing slot has proven to be successful, at least for the 400 mile the owner has clocked so far.
