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Charging Issues - 1000SP |
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FrozenSP 
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Joined: 31 Oct 2020 Location: Edinburgh, UK Status: Offline Points: 204 |
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 Topic: Charging Issues - 1000SPPosted: 28 Feb 2026 at 17:28 |
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Had the bike out for it's first proper spin of the year, freshly charged battery in, quickly noticed the charge light was out. It usually flickers when at idle, and it wasn't lit when the engine was off but the ignition on. It's an LED one, I changed it years ago when updating the dash, I remember wiring a resistor in at the time, but can't remember the value of the resistor. Didn't worry too much about it, figured it was just a blown bulb maybe, or that if there was an issue the light would come on rather than off. Did 35 miles to my stop point without problems, got back on an hour or so later, bike fired up fine and I was back on my way. About 2 miles from home, now tipping it down, the bike conked out at a set of lights. Hit the starter and.... click. Nothing, didn't even turn over. Fortunately I was on a hill, so turned the headlight off, and she bump started very easily - got home just fine. Took the battery out and it was flat according to my charger. I now remember that the charge light is an integral part of the charging system - but what I am confused about is if the light wasn't working and therefore the charge system not working, how was I able to do basically 70 miles before the bike died? And if it is the bulb causing the issue, is there a specific resistance I need to achieve? The bulb I used doesn't seem to be avaliable any more, there are similar styles (part FL1M-8CJ-2) avaliable with built in resistors, but can't seem to find a quoted resistance value. Cheers
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1982 SP 1000
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ranton_rambler
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Posted: 01 Mar 2026 at 07:39 |
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It’s got a big battery so will run the ignition system for quite a while even if not charging.
If the light doesn’t come on when you turn the key before starting, have a look at the fuses. It may mean the excitation current to the alternator is not there. I can’t remember which fuse that’s from. Ian
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Brian UK
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Joined: 13 May 2014 Location: Surrey Status: Offline Points: 18226 |
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Posted: 01 Mar 2026 at 15:22 |
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The standard charge warning light bulb is 12v 2.2W. That will pass about 200mA. So you need a resistor in parallel with the LED which will pass about 200mA at 12v. So you need something like a 60 ohm resistor. To be honest, I would always say the charge warning lamp is the only one that shouldn't be converted to LED. The fuse which controls that lamp is F3. But it also controls all the neutral and oil pressure lights, were they working?
Edited by Brian UK - 01 Mar 2026 at 15:35 |
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Dukedesmo
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Joined: 17 Apr 2015 Location: Leics Status: Offline Points: 926 |
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Posted: 01 Mar 2026 at 15:51 |
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Hopefully just a bulb or something simple but, recently my LM2 stopped charging as the rotor broke down so no voltage from the alternator.
Bike ran fine with no charge but would have stopped once the battery was dead, not sure how far that would be as it's a big battery. |
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Le Mans 2
Ducati 916 Ducati M900 |
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ranton_rambler
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Posted: 01 Mar 2026 at 19:38 |
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In my case I was running a RITA ignition which needs 11V to work. I rode about 40 miles and almost made it home, running out of sparks as I came down the lane into the village. Heavy old thing to push up the drive. Root cause was a fuse, which seemed to have failed due to vibration. Blade fuse, not the old type.
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FrozenSP
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Posted: 02 Mar 2026 at 17:16 |
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Fuses looked fine, and the neutral light is definitely working. Had a cursory check of the wiring (which is a mess) and nothing seemed to be unplugged or obviously broken.
Useufl thread, thanks. Am I right in saying that with the rotor failure you had, the charge light would light? I've taken the LED bulb off, was hardwired in with a 120Ohm resistor - unfortunately had to cut it out and messed up one of the terminals in doing so. Got 12V to it and.... it lit up. So, not the light. Will have to replace it anyway, but that's the easy option out unfortunately. |
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1982 SP 1000
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FrozenSP
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Joined: 31 Oct 2020 Location: Edinburgh, UK Status: Offline Points: 204 |
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Posted: 08 Mar 2026 at 12:56 |
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I am being a bit of a dunce here - but I'm very confused. Current situation is - charge light isn't working properly, and the oil pressure light isn't working either. 12v is getting to both. For the oil pressure light, if I put a continuity tester on the negative termial, the bulb lights up. If I put a continuity tester on the oil pressure sensor side, the bulb lights up. I can't figure why this light is not working. The negative terminal is wired directly to the pressure sensor, the positive is wired to the neutral light - which does work. I was under the assumption that if the oil pressure sensor failed, the light would come on. Putting a new LED in place for the charge light, and it lights up when wired in without a resistor in place. If I add a resistor in parallel (one leg of the resisitor to the positive and one to the negative) the LED goes out (ignition on, bike not running). This takes me back to the original issue of the bulb not lighting. There doesn't appear to be any direct wiring connecting the oil pressure sensor and the charge warning light, unsure why both have stopped functioning correctly at the same time. There are only 3 fuses on the bike, all are intact.
Edited by FrozenSP - 08 Mar 2026 at 13:36 |
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1982 SP 1000
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Dukedesmo
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Posted: 08 Mar 2026 at 14:05 |
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Yes but very dimly, so dim that I didn't notice it at first. In fact it was barely noticeable unless in a darkened garage.
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Le Mans 2
Ducati 916 Ducati M900 |
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FrozenSP
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Posted: 08 Mar 2026 at 16:09 |
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Some progress, and more questions. Traced a wire back from the charge light to the rectifier - circled  If I unplugged this connector and directly grounded it, the charge light lit up. Is this potentially a faulty rectifier? I tried cleaning the ground for the whole recitfier, and grounding it at a different position, but that had no effect. And I'm still puzzled as to why the oil light is off too, and why grounding the pressure sensor connection makes it work
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1982 SP 1000
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Mike H
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Posted: 08 Mar 2026 at 16:52 |
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What Brian said. Does your Spada have the 'idiot lights' on a circuit board in the dash? I well remember having to repair a second-hand Le Mans II one years ago, as it was badly corroded and it was quite a big job! There are so many spring contacts in the assembly, so lots of potential for bad connections. |
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"Chicken nuggets don't dance on a Tuesday."
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Mike H
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Posted: 08 Mar 2026 at 17:00 |
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Sorry only just seen this .....
It actually goes through the regulator, then the rotor winding to ground. I think the rotor connection is the one next to it on the rectifier board. There should be no current through the rectifier if engine not running. I would therefore test for continuity through regulator, and continuity through alternator rotor winding, and brushes.
Suggests pressure switch is open-circuit, i.e. failed. |
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"Chicken nuggets don't dance on a Tuesday."
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ranton_rambler
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Posted: 08 Mar 2026 at 17:40 |
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Multiple issues often point to an earth fault, but you really need to study the wiring diagram to find a common point which relates to all the faults.
I had an issue on a bike a few years ago and using that method pointed me to the keyswitch which had a bad contact on one terminal.
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Brian UK
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Posted: 08 Mar 2026 at 20:55 |
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If you have a multimeter, or can get hold of one, first check is to measure the resistance between the two brushes on the rotor. Should be around 4 ohms. If higher, then remove brushes, or put meter probes directly onto the rotor slip rings. Should be around 4 ohms. Occasionally there can be a fault in the rotor winding, basically it breaks. But you can also get a poor connection between the brushes and slip rings. Any problem round here will prevent charging, and mean the charge warning bulb doesn't light at any time. The other problem you can occasionally get is when the charge light comes on but never goes out. This can mean one of the 3 small diodes in the rectifier has failed. This is rare though.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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FrozenSP
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Posted: 09 Mar 2026 at 17:53 |
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Multimeter obtained, and it's looking like a rotor failure. Resistance shows as infinite when each probe is placed on each slip ring. Have removed the rotor bolt, but can't get the rotor/slip rings to budge. Guess it needs a puller of some form? The brushes on the stator are very unevenly worn, so will replace those.  If the rotor is indeed the cause, it means the oil pressure switch just happened to fail at the same time - what are the chances
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1982 SP 1000
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Mike H
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Posted: 09 Mar 2026 at 19:55 |
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Dang. Happened to me on the way home from somewhere in south of England, but it failed slowly, kind of thing, but ended up so I couldn't use lights or even indicators which put the Voltmeter in the red, I think it must have got home on battery only! Ended up selling the bike to someone who was going to restore it to factory so didn't get around to doing the actual repair.
The rotor is on a taper so you need the special tool to pull it off, Gutsibits have one, although originally it was a short hardened steel rod and you used it with the original fixing bolt. |
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"Chicken nuggets don't dance on a Tuesday."
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Dukedesmo wrote: