Charging system questions

[Drdds]

So I have a reasonably dry day (I wouldn't go so far as to say warm) so I finally get the Duc out to get it inspected and registered, then take it to run a few errands around town. Probably 7 miles tops all together. It was running great and right as I'm turning on to my street, I notice the instrument lights are a little dim, the headlight is a little dim, the engine starts to misfire . . . must not be charging my brand new battery right? Well I made it home, turned the bike off, hooked up my battery tender. I haven't had a chance to put a multimeter on to see what the voltage looks like yet, but I suspect the regulator as it seems to be a weak point. Naturally I'll check the stator wires and all vital connections, fuses, etc.

My question is this: There are lots of threads on how the regulator is a common fault and prone to failure. There are lots of threads on which aftermarket regulator is best or whether they are better than the updated ducati OEM part. There are also lots of comments that seem to show that all are prone to failure depending on who you talk to. This leads me to believe there is something else in the wiring that may be over stressing all these different regulators. Has anybody looked in to that at all? Does upgrading the stator wires to 10 ga wire improve reliability on regulators? Does moving the regulator to a location that gets more airflow improve reliability? Do we really know? Anyway, I've been looking through lots of threads here on this very subject, just wondering really what other wiring items should maybe be addressed to reduce the likelyhood of regulator failure. Thanks in advance for any opinions!

[MrSpigot]

I think the OEM Ducati SS regulators are likely to be a problem, particularly as they get older.....

.....firstly they don't appear to like heat very much, so consdiering where they get mounted, they don't exactly get to dissipate the heat very easily.....it helps to mount them on an aluminium plate using spacers to allow air to get all round them.

I have two OEM ones here, one from an 1993 bike and one from a 1998 (carb)......they are more or less identical and both have failed miserably because the tar / mastic / cr*p or whatever it is they seal the backs with has shrunk and cracked allowing water in.

The usual replacement is the Electrex RR51 which is simple to fit and wire.....It also does away with the big 30Amp fuse, although I don't think that is necessary to do that as it provides more protection.

However, I think the RR51 may chuck out slightly more than the battery needs, therefore I ride 'headlight on' most of the time.

AL.

[Stick]

First item to check is the 2 yellow wires that run thru bullet connectors on their way to the RR. The bullet connectors "weather", and turn crispy from current being forced thru a bad connection that gets worse over time.

If they're not crispy + hot when running, then disconnect them and measure the AC voltage at these to points.

Read up on this in the HOW section...

[Shazaam]

All motorcycle voltage regulator/rectifiers (RRs) - not just Ducati's - fail for two basic reasons:

(1) The RR overheats and damages it’s internal components.

The reason is that there is inadequate supply of cooling air inside the fairings and/or underseat areas where the RRs are commonly placed. The RR’s heat sink dissipates heat from the shunt regulator's main transistor which acts as a variable resistor to ground for the excess current. So, whatever current is not being used for charging the battery and running the bikes electrical system is converted to heat. A lot of heat.




Your only recourse is to move the RR to a cooler location.




(2) The stator wires short together and damage the RR.

As Stick correctly points out above, the electrical connection between the stator wires and the RR lead wires develop a small resistance caused by corrosion/oxidation. The wires need to pass in excess of 30 amps continuously so even this small resistance translates to a lot of heat being developed at the connector.



The insulation on the wires adjacent to the connector get crispy, but the entire wire needs to be replaced, preferably with higher AWG 8-gauge wires. The rest of the wire may not look damaged some distance away from the connector area but the insulation no longer is adequate to prevent the stator wires from shorting together where they are bundled together in a common sheath. When the wires short to each other at higher output voltages (engine rpms) the regulator's circuitry gets damaged.

So, all owners should take preventative action and eliminate the in-line connector and also move the RR for better cooling. Replacing a failed RR without addressing these issues often results in repetitive RR failures.

Do it now before you experience a failure.

[Drdds]

Both of these posts have been super informative, thanks you guys for your help. I appreciate the advice and Stick, I'll have a look at that how to section. I have two sick boys and a sick wife at home, so I have a feeling I won't get to checking things right away, but I'll let you know what comes of it when I do. I'm not addicted to performance mods (yet ) but I'm very in favor of ANYTHING to improve reliability.

On a related note as I've continued searching for information on this topic I came accross this Article posted by VA Duc (thanks by the way). I can't take credit but I thought I'd PDF it and repost a link to it here for any future Duc owners searching for answers. Super informative article to somebody new to motorcycle electronics, like myself

Ducati charging system article from VA Duc