Charging light staying on.

So, I've done a few jobs on the Commando over the winter. Last weekend I finally came to start the bike up and go for the first ride of the year. Over the lay-up I took the Alton apart to replace the original 3 dowels that had sheered and replaced them with the full complement of 6 of the newer type.

Just a few minutes up the road I noticed that the charge warning light came on - and stayed on. I didn't go far enough, or fast enough to see if it would have gone out in higher revs. I returned back home and started investigating.

As I pulled onto the drive, I looked down on the right and spotted a small spark between the exposed alternator leads and the engine cradle (I hadn't heat-shrinked them at this stage in case I needed to remove anything). I can't see any damage to the wiring.

As per Alton guidance from a previous post, I conducted the following test:

Fully charged battery (fitted with fuse out) - 13.9v

Static test (engine off)

1.1 Checked continuity between both AC Gen wires - continuity. Correct.
1.2 Checked continuity between each AC Gen wire to earth - no continuity. Correct.

Dynamic test (engine running)

2.1 Voltage from two AC Gen wires (disconnected from regulator) at approx 1.5-2k revs = 20-22 volts AC. Correct.
2.2 Connect up and start bike (1.5-2k revs) , DC voltage between battery terminals should be 13v DC - reading 12.54v. Hmmm!.

I hadn't changed anything electrically, but I noticed that each time I've installed the Alton stator over the magnetic ring, I've struggled to get good a clearance gap all the way around. I wonder if this is the problem? This weekend, I drilled .2mm from the three M5 screw holes in the stator in an attempt to give me a little more 'wiggle' room, and I feel that it gives a little better clearance, however the red warning light remains on.

I don't know if I may have lost some of the magnetism in the Alton ring due to insufficient clearance, and I'm unsure how I can test if that is the case.

So, where should I start?

Rectifier, then Zener? (I'm hoping the Zener is OK as I'd rather keep that with the original rectifier if I can).

My '74 Mk2 has the following (relevant to this charging issue):
Alton ES, Pazon Surefire IE, PVL coils, ICM charge & oil pressure light, original Zener & Lucas bridge rectifier. Motobatt MBTX20 battery (about 3 years old).

Where is the CWL connected to? Could be a poor resistive connection btwn it and power or ground. Try it direct of both battery terminals to elominate a poor wire connecrion.

If the CWL is on steady, that indicates low charge volts...check their instructions to know the voltage lomits of red to come on. Do you have the oil pressure sender connected?
My ICM CWL goes out at just over idle, 1000+ rpm, as long as no major electrical loads are on...ive got led headlight and taillight.

If your running dc volts at 1.5k rpm is only 12.5 volts, but ac output is in spec at those reves, most likely a poor connection somewhere btwn alt and battery...so rectifier, ,zener, fuse connections, batt terminals or grounding points.

Try testing the output engine running with the zenner disconnected

Hello,

I also have an Alton so here are some thoughts

1) Timing and an electronic ignition that has spark retard into ATDC at under 500 rpm is number one for me. I had an old Boyer.
When I converted to TriSpark, no more dowel shearing. Depending on ignition age or brand, you might not have spark retard.

2) My Alton install ends up with about 16 thou rotor to stator gap all around. I don't think this is causing the problem you are having.
Do you know how old your Alton is? Has the Alloy skin covering on your rotor been scored by rotation or can you see the physical profile
of the magnets under the alloy cover skin? (If there is scoring, you may possibly have affected the magnetization of the stator

3) It would be nice to see the voltage at the battery at about 2500 rpm and 3000 rpm. And know for those readings if any lights are on ie a load.

4) I have had two connections that have failed and caused me a problem. One spade connector from stator to connector fin primary chain case lost tension (lower charge voltage) and then latter cracked due to vibration I guess. I now just solder the wires to connect them. The second connector problem was where the two wires that comes out of the Alton are connected to your wiring harness. My crimp was not tight so I found I could pull the wire out of the connector.

5) I suggest to check all connections between the Alton and battery. All spade connectors should be tight to pull apart. If they are not tight, don't squeeze them to make them tight. It does not last. Replace them with new connectors. The male spade part can be cleaned of visible and invisible corrosion. In addition, recrimping each connector to its wire is a good idea even if it seems tight

6) I suggest to check that the grounding connections are all good with tightness and no corrosion.

7) I suggest to check the resistance of all wire runs. One thing you can do to check a run of wire, with connections in it, is to check battery voltage at 2500 rpm and then bypass that run of wire with a test bridging wire and run engine at same rpm again to see if battery voltage increased. If Yes, the problem is caused by what you bypassed.

8) I also suggest to check the Zenor. The easiest way is to unplug it and run engine. But check wiring diagram first. If you unplug it and run engine and you get more voltage at specific rpms, it is dropping voltage. If unplugged, it will not prevent overcharging of the battery (which is its function)

9) I hope others can comment if I have covered everything. When all is covered and battery is a known good one, then it points to the rotor.

10) That leaves one more.... can you substitute a known good battery? Even if it is an external fully charged good car battery sitting on the floor wired up to the bike

Dennis

Bonzo said:

So, I've done a few jobs on the Commando over the winter. Last weekend I finally came to start the bike up and go for the first ride of the year. Over the lay-up I took the Alton apart to replace the original 3 dowels that had sheered and replaced them with the full complement of 6 of the newer type.

Just a few minutes up the road I noticed that the charge warning light came on - and stayed on. I didn't go far enough, or fast enough to see if it would have gone out in higher revs. I returned back home and started investigating.

As I pulled onto the drive, I looked down on the right and spot a small spark between the exposed alternator leads and the engine cradle (I hadn't heat-shrinked them at this stage in case I needed to remove anything). I can't see any damage to the wiring.

As per Alton guidance from a previous post, I conducted the following test:

Fully charged battery (fitted with fuse out) - 13.9v

Static test (engine off)

1.1 Checked continuity between both AC Gen wires - continuity. Correct.
1.2 Checked continuity between each AC Gen wire to earth - no continuity. Correct.

Dynamic test (engine running)

2.1 Voltage from two AC Gen wires (disconnected from regulator) at approx 1.5-2k revs = 20-22 volts AC. Correct.
2.2 Connect up and start bike (1.5-2k revs) , DC voltage between battery terminals should be 13v DC - reading 12.54v. Hmmm!.

I hadn't changed anything electrically, but I noticed that each time I've installed the Alton stator over the magnetic ring, I've struggled to get good a clearance gap all the way around. I wonder if this is the problem? This weekend, I drilled .2mm from the three M5 screw holes in the stator in an attempt to give me a little more 'wiggle' room, and I feel that it gives a little better clearance, however the red warning light remains on.

I don't know if I may have lost some of the magnetism in the Alton ring due to insufficient clearance, and I'm unsure how I can test if that is the case.

So, where should I start?

Rectifier, then Zener? (I'm hoping the Zener is OK as I'd rather keep that with the original rectifier if I can).

My bike has the following (relevant to this charging issue):
74 Mk2. Alton ES, Pazon Surefire IE, PVL coils, ICM charge & oil pressure light, original Zener & Lucas bridge rectifier. Motobatt MBTX20 battery (about 3 years old).

Click to expand...

Test the bridge rectifier using the procedure in the manual.
I had a failed diode a couple years back. Same symptoms.
Rule it out.

As for sparks from Sparx... well, fix it, even though it tests ok.

Thank you gentlemen.

I will digest, check & report back

Bonzo said:

Thank you gentlemen.

I will digest, check & report back

Click to expand...

Bonzo,
Make sure your connection to the oil sending unit is good. I had the same problem with the light staying on until I saw the wire had fallen off.
Mike

Just to close this thread off, I'm happy to report that the bike is now charging at 14.4v @3,000 rpm.

Today is the first chance I've had to dig into it and having read up from various sources and following the advice above, I traced the fault to - none of the above!

It was actually a dodgy bullet connector in the harness between the alternator wires and the rectifier.

If nothing else, I've gained a little more knowledge of electrics and that can only be seen as a win.

Thanks again for all your input folks

*LATE EDIT* I'm sat downing my last cuppa of the day, when it dawned on me that despite what I wrote earlier (I traced the fault to - none of the above!), the answer was actually above - and mentioned in the thoughts of @DennisMo (4.) - cheers mate

Good job there Bonzo!
I too had a similar problem and found that one of my wires to the regulator was disconnected. I did a lot of work lately on my bike and got tired of fishing around those bullet connectors and started converted new wiring over to the WAGO connectors. Such a simpler and more reliable connector system. I ended up doing this for my rear end where the tail lights and signals are, and under the gas tank for a few connectors. I'll end up replacing the others over the winter or next spring. After all of that I realized how many dangling non-used connectors are on the harness and really thinking that I should replace the harness to get rid of all those loose connectors taking up space. Just a thought at this point, but at some point I will likely do that.

WAGO connectors eh?

I'll head over to google & check them out

WAGO. Yup!
This is what Matt uses and sends out with his kit.

I bought his assortment from Amazon.

WAGO 221 Lever-Nuts 75pc Wire Connector Assortment Pack with Case​

They work great!
No idea whether they will last 50 years, but will likely outlast me.

They look good!

Anything that makes connecting wires easier (for me), is good news.

Thanks for the tip