Still having problems with the SP3. A few weeks ago it left me stranded, turned out to be a flat battery, a consequence of not charging. I replaced the RR (decided to fit another Electrex unit rather than a MOSFET, maybe next time). Now I get about 12.? across the battery at tickover, rising to high 13s at higher revs so unless I'm pushing on, the battery probably isn't getting charged. The voltage across the two yellow wires from the alternator (disconnected from the RR) is all of 11VAC at tickover, rising to nearly 30VAC at 5-6000rpm. I measured the voltage from each yellow wire to earth, it's about 5.5VAC in each. I understood that I should be seeing about 30VAC across the yellow wires at tickover, rising to 60-70VAC at 6000rm. So, is the rotor knackered? Could the magnets in the rotor be weak? FWIW I had the battery load-tested, it's OK (but not great). Any thoughts? Thanks Andrew
Mid 13v range is a good charging rate. My second Electrex reg/rec had an intermittent fault, it jumped from charge to non charging with a mind of its own, I was lucky enough to have a charging monitor on the bike so I knew what was happening before it let me down. Steve
I just ordered a battery voltage monitor from SparkBright (I think you have one of those?). Should arrive tomorrow so we'll see what that tells us.
You need to connect the monitor directly to the battery to get a correct reading, I wired a relay into mine triggered by a live wire when I switched the ignition on. If you just connect it to any old switched live it will show a lower voltage, I tried a few before I realised. Steve
Yes, I have an Optimate lead permanently attached to the battery - I'm going to plug it into that in the first instance.
Mid 13V is not a good charging rate, there should be a minimum charging voltage of 13.7V. I have a MOSFET regulator on my 907ie (same alternator as the 851) and it puts out 14V at idle and maintains 14.4V at higher revs. Your stator should put out about 15V ac per 1,000 rpm. So you should be seeing about 15V to 20V at idle and about 60V to 80V at 5-6,000 rpm. It sounds like your alternator isn't putting out as much as it should. Are connectors to the 2 yellow wires in good order, not burnt and/or corroded? Check also that the 2 yellow wires don't show any connection to ground, i.e.infinite resistance. The insulation of the stator may be breaking down under load. If the stator is ok, the rotor may have lost some of it's magnetism.
Odd you should say that Derek but you have much more knowledge on such matters than me. My experience with my 748 single phase alternator has given around 13.6 vaults max charge over seven years on the same battery and it's never failed to start first touch of the button. Shouldn't speak too soon, perhaps I've been lucky. Steve
13.6V will keep the battery charged, but just. It will keep the battery maintained at it's charged voltage, but if the battery is down at all it will never reach a fully 100% charged state. If your bike is in a good state of tune and starts easily you obviously get away with it but a bike that is a poor starter could pull the battery down and would struggle to get it fully re-charged with normal running.
Thanks for your replies. Derek, I thought I should be getting 14 - 14.5V at pretty much all rpm (it's what I get on the 1198S but I think that has a three phase alternator?). I'm definitely not getting the sort of voltages you mention across the two wires from the alternator - it's 11VAC at tickover across the wires, 5.5VAC across either wire and earth. Which sort of suggests the rotor is not doing its thing. The wiring looks to be in good condition and the connections to the RR are new (bullet connectors). I'll check for any resistance to ground. Is it common for the rotor to lose magnetism? Seems to have happened fairly suddenly if that's the case (all seemed to work fine until recently). Steve - I just connected up the BVM, direct to the battery as described. With the ignition switched off it's steady amber; with the ignition on but the engine not running it flashes red (slowly). When I start the engine the light goes green at around 2 - 2500rpm and stays green up to around 5000rpm (although this was in the garage so I didn’t hold it there for long). At tickover it gives a double red flash. All of which seems to be consistent with the alternator not putting out enough charge I think? Maybe it's time to risk a short ride... Andrew
It looks like the stator winding is shorting to earth. With the engine running there should be 0V AC between any of the wires and earth. It sounds like the insulation on the stator windings is allowing a contact to ground somewhere. A resistance check should conform this. It may be the one of the windings is touching metalwork somewhere and the varnish insulation has rubbed through, which could explain why it happened suddenly.
I'll get the meter out again. I think I'd rather it was the stator - I think on these bikes the rotor is attached to the flywheel in such a way that the flywheel has to come off???
When my ignition is switched on I have a red flashing light, when I start it up it goes to green charging, it then stays at green for a while until ( I presume) the battery is fully charged and then it will drop to a flashing red at tickover with headlights on, as soon as I blip the throttle it goes straight to green again. Steve
OK, I tried to check some resistance measurements. First up, the meter I have probably isn't the best (it's a Rapitest DM25 which I've had for years). In its defence though, I found a couple of loose resistors in a box in the garage, and they measured as follows: 21.7k for a 22k, 987 for a 1k so I guess it's not too bad? On to the bike... Measuring across the yellow leads - with the meter disconnected it reads "1"; with the probes shorted together, "00.0"; connected across the two yellow leads, "00.2" to "00.3". All this on the 200 ohm range. Measuring between either yellow lead to earth, the meter always read "1" at all ranges from 200 to 200M ohms. What does all that mean???
These measurements are all as they should be but there should definitely not be a measurable voltage between any of the 2 yellow wires and earth. It may need something like a megger to check the insulation but that's something I've no experience with.
Just remembered something else. After the bike left me stranded the other day one thing I found was that one of the connections from the alternator to the RR had broken, so I assume that the alternator had been operating like that for a while. Could this have damaged the stator? Overheating perhaps?
I really don't know but since no current would be flowing it certainly wouldn't be overheating. However, with no load the stator would be creating some quite high voltages which may have been enough to cause the insulation to breakdown, but that's just surmising.
After Derek posted earlier it got me a bit concerned as I have relied on my on board monitor for years now, so I had a recheck this morning and found it is reading 14.01 with the fast idle button pressed in. A relieved Steve.
