Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > 916 charging problem...yes, another one!

[cliffwalker]

Just to confirm, I'm pretty sure the alternator is duff as its putting out half (or less than half) of what it should be doing (and I'm testing it as close to the alternator as I can get, only one inch of cable coming from the alternator cover).
Therefore the problem is not the yellow cables that run from alt to reg/rec.
What I'm asking is why my charge light is now on and why its blowing fuses within a mile.
I'm quite prepared to change the alternator, as I have a new one sitting on a shelf (and by new, I mean a brand spanker, still in the box) but I'd like to know if there are any things I should know before starting (it seems an easy swop, but I thought I'd check first)
The second thing is, I'm wary of why the gennie light is now on (when it wasn't before, or blew fuses before), what triggers the warning light, as I don't want to fit the new alternator and then find the light stays on, the fuses still blow and I have a different problem to fix.
As I said, the low charging never bothered me too much as most of my riding is long journeys with few stops, so I could put up with it.
What I don't want to do is swop the alternator and still have the problems.
The reg/rec is a separate issue. I don't know if there is a problem with it or not (many of your answers seem to concentrate on the reg/rec, even though I initially said my alternator was duff and didn't mention the reg/rec)
I can't test the reg/rec when my alternator output is wrong (or can I?)
Am I right thinking that the 600 Supersport is the same reg/rec, I know someone who's reg/rec I could borrow if so.
I do have a 3 phase reg/rec from a later bike, can this be used at all or have I got to buy a 2 phase?
Sorry for so many questions but the replies I've got so far weren't answering the original question (why is the light now on and why is it blowing fuses all of a sudden?)
I'm guessing the answer will be that the reg/rec is now also faulty, so that's why the fuses/light etc, but I'd still like to know why?
What signals the light to come on?
I'm thinking a voltmeter is going to go back on the bike when I've sorted it...
I'm having a bad month, my Guzzi seized three weeks ago too.
This is getting an expensive month...

[keith888]

I think its likely from what you say that both the alt and reg/rec are duff. As you say you cannot check the reg/rec with a duff alternator (except putting it on another bike) though blowing fuses with a reduced alternator autput suggests it is faulty. Thus, if you are convinced the wiring is OK then you should replace the alt and recheck. If the unregulated output is OK but you still do not have good charging when you connect the current reg/rec then replace the reg/rec and try again. My understanding is that the 3 phase reg/recs will work fine on only 2 phases (try searching the forum).

Dunno how the reg/recs are wired internally but in cars the light comes on when alternator output is less than battery voltage. This could be due to either weak alternator or failed reg/rec so the light coming on doesn't help you much. The fuse blowing does suggest it is faulty though if the wiring is OK.

Keith