Went for a two hour spin Sunday , got back battery indicator was red , did all the checks , Battery Parasidic drain is 0.8ma , all good Charged battery 13.41v Let sit for 2 days 13.26v Turn on the ignition, lights for 2 mins, then off 13.1v Cranking the bike battery dripped to 11.2v momentarily, cranking amps all good Warmed up the bike , turned off , started , tested regulated output , while slowly increasing rpm to 3k , 14.1v I am happy battery is good , and the rectifier but I am not happy with the wiring , few years back I removed the plug and connected the wires together to form a water tight seal , I know a few people use a MOSFET rectifier and heavier guage wire or oe rectifier and heavier guage wire , some move under the seat I notice loom (yellow wires) goes in behind the rad overflow tank above the crankcase , Does anybody know of a guide on how to replace the wiring , what is the recommended option MOSFET ? battery is good , 14.1 across the battery with engine on but wires don't look good
Carlo, that’s a ticking bomb. Are you still using the std rectifier? If so, swap it out for a mosfet jobby and get those terminals insulated. Drop me a pm if you want and I’ll walk you through it.
first class offer from Ian (bettes) and plenty of threads on here to swot up on, just type "replacing rectifier 748" into Google and top two options are Ducati.ms (an excellent source of info) followed by this Forum.
There's no good reason to replace a functioning Ducati regulator/rectifier. The problem shown in the picture above is that the original bullet-style connectors have developed some electrical resistance. Every motorcycle has a potential problem with this connector. The in-line connector is not sealed against moisture, so eventually, the connector corrodes/loosens, and along with adjacent wire insulation, overheats and fails. This is a potential failure mode for any motorcycle, not just Ducatis. These wires have to pass high amperage continuously. There’s an electrical phenomenon called I-squared-R loss. That is, if you run 30 amps through a corroded or loose connector having (say) a small 1/2-ohm resistance, the heating effect is 30 X 30 X 1/2, or 450 watts. That’s a lot of continuous heat. This heat just conducts down the wire, cooking the insulation as it goes. Just like you can’t put your hand on a 450 watt light bulb while it’s lit, you can’t expect a plastic connector to survive radiating 450 watts of power either. A corroded or loose connector always has a higher resistance than the adjacent wires and it will heat up enough to melt connector plastic parts and nearby wire insulation. That’s why it’s best to solder the wires directly together and eliminate connectors entirely. If you don’t want to eliminate the in-line connector then replace it with a more secure connection, preferably one that is sealed against moisture. Here’s a couple of examples: Changing from the stock shunt R/R to a MOSFET unit will reduce the heat generated in the R/R body itself but the likelihood of the problem with overheated connections is not reduced.
Melted COOL SOLUTIONS Ducati shunt-style voltage regulator/rectifiers get hot— that's why they have cooling fins and why they are best mounted in a location where they experience good airflow. Left idling in a garage doesn't supply much cooling air. When they get hot enough — they fail. MOSFET-style rectifier/regulators produces less heat as less energy is lost through the switching process — so they run cooler and more efficiently. Some owners use these as a replacement. Early 916/748 have the R/R mounted inside the fairing where there's inadequate cooling air. Later models had bigger air ducts. The solution is to relocate the unit outside the fairing. Here's my solution:
"There's no good reason to replace a functioning Ducati regulator/rectifier." ^ That's a bit of a generalisation isn't it?. I agree with you certainly for 1991 onward SS/Monster/Elefant/748/996 etc but not for 848/1098/1198 as it's in a poor position to begin with, and standard unit far more likely to fail compared with a later, cooler-running Mosfet equivalent, or even the latest units available.
They are inline crimped connectors with heatshrink , are still seeing excessive heat to cause a potential fire Oe bullet connector was replaced
Steve ( @ Birdie ) on here pretty much pioneered that fitment/positioning for a rectifier over 10 years ago - documented on here somewhere already.
First sentence:"When you relocate your regulator to behind the license plate..." http://www.ducatisportingclub.com/images/dsc/shazaam/RelocatedRR.jpg
I know that I'm new here. I think there's a number of Ducati Sporting Club expats here that will vouch for me. Here's some of my old posts: https://www.ducatisportingclub.com/forumdisplay.php?f=182
I found upgrading to the newer Pani unit (also used on other bikes) with the Triumph cables was the best solution.
Putting the reg/rec behind the number plate is fine if you have clean roads, I guess. I installed a mosfet (Yam R1 off ebay) in the standard location. They run cooler anyway, and the lower fairing vent is all it needs, imo. Upgrading to beefier wire from near the stator all the way across to the reg/rec is also important. Had the same issue on my SV650 and VT250 long ago, both had shunt rectifiers.
Shazaam, I've been reading and referring to your posts for years and years, I'll take this opportunity to express thanks. Glad you are here. Cheers Grant
