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1098s Alternator/regulator Problem?

Discussion in 'Technical Help' started by Symon Moore, Apr 12, 2019.

  1. I need some work done to my 1098. Normally I’d use JHP but they looked at this problem late last year, diagnosed a battery fault, replaced it & all seemed well. Until now, where the same thing has happened again. I’m sure it’s a reg/rec problem (idiot lights erratic, main beam cuts out, higher than usual idle & the “Hi” voltage indicator on the dash). I know this model has a high temp regulator & that they do burn out, but over the phone, JHP are now saying it’s probably that the alternator needs a rewind. This is apparently a big job & I might be looking at c£400 plus. Also they can’t even look at it for another two weeks at least. So...spoke to Neil at Cornerspeed & apart from the fact that I’ve got to get the bike to Nottingham which is a bit of a problem, they seem to be more open to it being a regulator problem. However they can’t look at it until the end of the month!

    So a couple of questions guys:

    1. Any overall advice as to the actual problem?
    2. Has anyone used a local bike technician/repair shop/mobile mechanic etc that may not be a Ducati specialist & how did that work out?

    Appreciate any advice, particularly if it leads to me getting the bike sorted in the next week or so & doesn’t involve me having to be economical with the truth to the missus again
     
  2. An excessively high battery voltage will cause problems with the lights and indicators among other things. The "HI" indication on the dash would confirm this. I have worked with bike electrics for many years and I have never known a faulty alternator to cause a high battery voltage. The problem almost certainly lies with the regulator which is an easy diy swap.
     
  3. Agree. Alternator problems (burn outs, shorts etc) normally result in under-charging and a flat battery.
     
  4. Regulators occasionally fail with an overvoltage fault. Higher than 16.1V will cause the dash to read "HI".
     
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  5. Yeah I raised this last time round & wish I’d gone down that route when the battery work was done but as I say Ducati (or JHP at least) are saying it’s probably the alternator. I’m not convinced as all the symptoms say regulator to me but to be honest, I just don’t know & don’t want to waste time & money again. Really need someone smarter than me to look at the bike & tell me for sure what the issue is. Without having to wait nearly a month for either ‘specialists” in my area to take a look. Anyone used a local mobile mechanic for their bikes? Is it worth it? I just don’t know.
     
  6. Bit out of your way but in Cheltenham - Richard is (or was on here) and is a Ducati fan.
    He knows his stuff - but why not follow Rob's advice and just swap your Reg / Rec. People like Derek are always on standby to help with their electrickery knowledge :):upyeah:
    http://www.motorcyclewiringspecialists.co.uk/home.html
     
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  7. Surely this is the standard Ducati stator set up?
    Assuming the design is correct, then as long as all three windings have integrity they will produce a sine wave charge.
    High voltage at the battery can only be produced by a failing regulator.
    Is the 1098 one of the bikes where perhaps too much power is being made for a weak regulator, perhaps located in a very hot place?
    The rewind is to reduce the power made?
    The advice of a better regulator circuit being moved to a cooler location would be both prudent and expeditious.
     
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  8. Sorry Aircon, most of that is way above my pay grade! You’re suggesting upgrading the regulator I assume?
    What is the bit about three windings & as you appear to know what you’re talking about, why do you think JHP are telling me I need an expensive alternator rewind instead of a £90 regulator replacement?
     
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  9. Just follow Rob's advice and copy this - you don't need educating - it all witchcraft anyway, Derek and AC are Warlocks :eyes:
    https://www.ducatiforum.co.uk/threads/mosfet-regulator-installation.68657/
     
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  10. Symon, 5 minutes with a voltmeter is all that is needed to confirm this is a regulator fault and as Derek has mentioned regulators do fail on occasion to high voltage (I have had one do this on a 748). Simple checks are:
    With the ignition off measure battery terminal voltage - to confirm approximate health of the battery - good is normally indicated by >12.6v dc
    Start the engine and measure the battery voltage at the battery terminals on tick over (lights off) and as the engine is revving. If the voltage exceeds 14.6-15V you need a new regulator/ rectifier
    To diagnose a stator issue you measure the ac voltage across each of the three yellow stator output wires they will vary depending on engine speed but should be in the range 15-80v ac depending on engine speed and should all be roughly the same voltage. If one pair of wires is very different in Vac that stator coil will be fecked. Stators do not fail to higher voltage.
    Whist you are down there it is advisable to check the condition of the stator to regulator connector as any burnt pins will lead to a premature failure of your new regulator/rectifier

    JHP suggest an alternator issue which is technically correct if the regulator is at fault as the charging system (alternator) includes the generator/stator as well as the regulator rectifier.

    If the regulator/rectifier has failed then it is a simple swap for a new OEM replacement assuming the connectors and cables are in good nick. You don't need to 'upgrade' to a replacement mosfet regulator although some maintain it is a good idea.
     
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  11. @Robarano @Denzil the Ducati @AirCon @Exige @Derek @razz A personal thanks for your words & advice on this thread. Ordered replacement mosfet, friend machined a bracket, I fitted it back on this morning & all is well. Total cost to me £72.99 to eBay & a pint for Steve’s machining skills. Satisfaction level & confidence levels through the roof. Cheers all, I honestly wouldn’t have even tried without your feedback
     
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