Charging System - SP

hindsight

Hi guys

I've got a charging system issue - I'm not getting a significant voltage increase once the engine is up and running. I've replaced the RR, and the symptoms haven't changed.

I measure around about 12.58V with the engine at 4000rpm, and 12.53V with ignition on, but engine stopped. I also measure 40V AC from the alternator at 4000rpm.

It's a SP5, with the low-output (300W) alternator - this post: http://www.ducati851and888.com/showt...&highlight=40v

..seems to correlate the 40V AC output as being normal for the 300W alternator - in which case, I suspect that the replacement RR is probably as faulty as the original.

What do you think?

brad black

possibly - http://bradthebikeboy.blogspot.com/2...tem-issue.html

and this - http://bradthebikeboy.blogspot.com/2...procedure.html

use a little rectifier to see how much voltage it's capable of.

hindsight

Thanks Brad - I had read your SP4 fuel pump issue. I changed the fuel filter about fifty miles before I discovered the charging issue, and didn't note anything untoward with the contents of the tank or the state of the filter that came out, so I don't *think* there is much of a problem there.

All connections are clean - the alternator yellow wires have seen some heat, but are not damaged or melted like I've seen in the past, so I think they're good.

For the rectifier that you mention - would just a small generic part like this work for diagnostic purposes?

https://www.ebay.co.uk/itm/4-Wire-Full-Wave-Motorcycle-Regulator-Rectifier-12V-DC-Bike-Quad-Scooter/153119306322

hindsight

I just remembered that I have a RR from my 916 in the garage that should be good, I quickly lashed it up, and seems to be returning similar results. I'll try again next week when I get back from Silverstone

brad black

rectifier only.