Checking power output from DC lighting coils, how?

[Paulnobodyimportant]

This is a DC converted Lambretta with a BGM v3 (DC) stator, BGM flywheel, wassel unit and 12v fused battery, all fitted by me, probably 12 months ago.

However, on the last couple of night runs, the lights have faded away to nothing.

So far I have checked the wiring for earth leaks and continuity, but all show OK and the fuse has not blown.
This morning I checked the battery voltage with no engine running and it showed only 10 volts. So connected meter to the red power output from the wassel and revved the engine up, but the voltage never got any higher than 0.5 volts.

Now it could be a faulty wassel unit or the BGM lighting coils have failed.

But how do I check the lighting coils?
For instance, can I connect my meter to one of the yellow wires coming from the stator (because there are two yellow wires). If so, what kind of reading should I be expecting with the engine running?

Thanks
Paul

[coaster]

First thing to remember is that the job of the voltage regulator (Wassel) is to dump surplus voltage to earth. Therefore, if there is no load connected to it (i.e. you have unplugged the red) the unit will send almost all the current to earth. You need to have the wassel connected to the loom and connect your volt meter across the battery. Start the engine and the voltage should rise to anything up to 14 volts depending on revs. Switch the lights on and the voltage will drop a volt or so and is unlikely to put out sufficient voltage to charge the battery at low revs.
As for testing the lighting coils, you could check the resistance across the 2 yellows but the reading is unlikely to tell you much other than to confirm continuity as the coil resistance is very low i.e. less than 1 ohm). You can check the output volts though which will be AC and should go up from around 5 volts to around 30 volts as you rev it.
As a matter of interest, what size headlamp bulb are you using? I was using a 60/55 watt Xenon and the battery needed topping up if I did a lot of slow ridding.

Just thought of something else, I had some problems with my lights recently and found that the spade terminals on the fuse holder had oxidised and formed a high resistance. That fault had been on for nearly a year as well

colin

[Captain Pugwash]

Like coaster says, but don't be surprised if you see over 60 volts ac from the stators yellow wires with a good rev of the engine, as they can produce very high unregulated voltages, especially with all Four of the lighting coils joined in series.

PS
The lighting coils are ac, or (that is they produce) alternating current which is later rectified by the Wassel unit, so you test the coils direct from the stator via the two yellows with the multi meter set to ac on a voltage setting normally above 100 volts.

[Paulnobodyimportant]

Thanks for the replies, I'll connect the red power back into the loom and test across the battery. As for the headlight, its the Jokeys boxenstop one ( http://www.jockeys-boxenstop.de/shop/en ... -3885.html) that I think you have as well Colin and its in my Series 80.

As for the two yellow wires, do i join both up to see the combined voltage

[Nelly]

Don't join the yellows, you need to read the voltage across them. Put the red probe/clip on one yellow and the black on the other yellow.
If you join the yellows you will cause a short circuit. You must have the multimeter set to AC voltage setting too.

[coaster]

..... As for the headlight, its the Jokeys boxenstop one ( http://www.jockeys-boxenstop.de/shop/en ... -3885.html) that I think you have as well Colin and its in my Series 80.

Yes same here except I now have a cheap ebay HID kit installed which makes for an AMAZING headlight and is still only rated at 35 watts

[Paulnobodyimportant]

Think I may have sorted it. Trouble is there just aren't enough hours in the day. So in garage this morning at 6 rushing to get things done before the day job. Now I thought I had done all continuity checks, but realised today that I had missed the Brown cable in the loom to the headset. Anyway it failed. So quickly by passed with a duplicate wire and all seems to work. But now had to rush back into the house to perform my duties. But prior to that did check across battery terminals and only got 10v, but that's obvious as it was not being fed from stator. Checked across two yellow stator wires and got jumping amounts up to 45ac voltage, which I guess is reasonable. Will come home early tomorrow and sort out, but thanks for the pointers. And Colin did read your lighting thread with interest. One day I'll have a go.

[grandpa]

Hi Paul,
If you connect a 55watt car headlamp bulb across your two yellow stator wires the bulb should shine brightly proving your stator can handle a load I.e 55watts
Grandpa

[Wack]

I'd say your battery has had it.

[Paulnobodyimportant]

Just had a look at the wiring this afternoon. Yes, battery may be kaput and i have a spare one.
Anyway, just pulled lighting switch away from housing to look at connection. First thing was to do a continuity check on the on/off switch for the lights (black button.) so when switch is off, then the continuity check registers 1 which is the correct result.

However, when I put the switch on, the resistance is 500+ ohms. So is this the problem of no lights or horn?

Plus, doing a continuity check on the soldered positive terminal to the horn and to earth, I get zero ohms whether the horn button is pressed or not.