Blown LED bulbs on B31

[coline]

Does anyone have any idea what has caused my head light, pilot and foot brake led bulbs not to work (my rear light is still working) on my 1949 B31. I presume they have all "blown" as I have been told they are very sensitive to voltage variations?
Thinking it is my (solid state) regulator that is faulty I took a reading across the battery as follows:

Engine not running- 6.45 volts;

Engine ticking over- .1 volt

Engine revved- .11 volt

This has left me puzzled. Any help would be gratefully received.

Colin Edwards, Mid Wales

[limeyrob]

Hello. Is it 6v or 12v?
The volts for "engine revved" is that 11v or 0.11v?
I have not found LEDS to be voltage sensitive, quite the reverse, I run one bike on a 14.8V total loss set up and the 12V LEDs work fine.  What I have noticed is that LEDs don't "glow" when the voltage is low, they either work or they don't.  What happens if you hook up a charger to the battery?

[rhyatt]

your 6v battery standing at 6.45volts is fine for a 6v system.
it should increase when the bike is running/charging to about 7.2 - 7.5 volts and top out there
as mentioned, the LED bulbs are surprisingly forgiving.

normal switching is pilot and tail(and speedo maybe) and these stay on when the switch is turned to Headlight position

have you removed each bulb and put across a good 6 volt battery?

of course - all the bulbs in the front end rely upon the same single earth connection - the tail light is completely separate - have you lost the earth at the front ??

[Rog1]

Electronic multimeters can react badly in the presence of old motorcycles; apparently it's radio interference. My DVR2 electronic regulator regulates at a steady 6.9 volts according to my analogue (moving needle) meter, but the readout on my digital meter flickers between 1.2 and 18.5 volts on the same regulator.

Some meters are well shielded, other cheaper ones are not, I'm told. My digital meter must be one of the cheap ones.

If you ask around there might be somebody you know with an analogue meter, like my Avo 7 (Avometer 7) which is about the same age as my '54 M33. I don't know if modern analogue meters are unaffected by interference, or suffer from it like my digital one.

[neil1964]

Electronic multimeters can react badly in the presence of old motorcycles; apparently it's radio interference. My DVR2 electronic regulator regulates at a steady 6.9 volts according to my analogue (moving needle) meter, but the readout on my digital meter flickers between 1.2 and 18.5 volts on the same regulator.

Some meters are well shielded, other cheaper ones are not, I'm told. My digital meter must be one of the cheap ones.

If you ask around there might be somebody you know with an analogue meter, like my Avo 7 (Avometer 7) which is about the same age as my '54 M33. I don't know if modern analogue meters are unaffected by interference, or suffer from it like my digital one.

I too have got AVOs meters (x3 mine are early and late 60s) which I really like but I use a Fluke 115 for most things as it is light accurate and easy to read. The AVOs come out when measuring over 600vdc.  When testing the 12v DVR conversion it behaved normally, charge was very healthy with (iirc) 13.5vdc @ approx 2000rpm. The precise numbers elude me because I was delighted to see such healthy output at relatively low revs I do not dwell on the numbers.

Colin - have you tested your Dynamo on its own (out of circuit with main harness)?  Is it polarised correctly?

[coline]

Thanks all for your replies, really helpful. Mine's a 6v. system. I have tested the bulbs on the bench with a new battery and got nothing from the bulbs. I just assumed that the battery would be OK without testing it so I will do that now. I haven't tested the dynamo either in or out of circuit. How would I test it out of circuit/ off the bike? Oh, I should have mentioned I have fitted a Thorspark electronic ignition with a coil which has worked perfectly for the last 2 years. Don't know whether that affects anything?
Many more thanks

Colin

[Steve.S]

Mr. E, It sounds like your dynamo and LED's are FUBAR, but bear in mind some LED's are polarity sensitive. Just to confirm, your battery drops from 6.45 volts to 0.1 volts when you start the engine? Something seriously wrong here. No wonder your LED's don't work. I'm surprised nothing has caught fire or blown up. Are you sure your readings are correct?
To test the dynamo on the bench, just run it up on a drill in the correct direction of rotation....preferably a mains drill, as they tend to run faster. You could bend the locktab on the bolt back, and try a socket, but the hex is very thin, so you may need to grind the socket back to remove the internal chamfer, or fit a bolt with a deeper hexagon. Alternatively, remove the pinion and use a short length of rubber heater hose and a couple of jubilee clips.
You should get about 1 volt on the dynamo wire alone and voltage should then increase when you connect the field wire.
Just join the 2 wires together and connect an analogue voltmeter to this and the body. It should produce more volts than you need, but to check it has balls, connect a 40W bulb, this will blow if you leave it on for more than a second or so.
You could also do a motoring test and check the dynamo polarity... search this site or the internet for info.
The fact that the engine is running indicates there is nothing wrong with the Thorspark.....but nothing is certain.
If all the above tests out OK, then it's either the regulator or wiring/switch.
Sorry to be pedantic, but what you have written is Minus zero point 1 volt etc. I guess you mean 0.1 Volt? Is your meter working OK?

[limeyrob]

I know its a little off topic, but on a 49 B31 I would run a magneto. The 6v charging systems in this period were made to run with a magneto which looked after the engine so the two systems were separate which gave much better reliability.  Light and battery problems were common but engines kept going.  Its why a lot of light aircraft still run magnetos and recently there was a fatal crash of a home-built because the pilot/builder thought he could improve it by removing the mag and fitting electronic ignition.  What he did was make the reliability of the engine dependent on the charging system and battery, which failed and took the engine with it.  The Historic Flight aircraft which are close in age to your bike are flying about fine on magnetos.

[Steve.S]

Thank you Rob, you've just reminded me that Mr. E is using a coil. It seems to me that a coil which will produce a spark big enough to run an engine when fed with 0.1 volts should be in the Guinness Book of Records.

[neil1964]

Have a look at these, very comprehensive and clear from James Smith on the Matchless forum:

How to test a Lucas dynamohttps://www.matchlessclueless.com/electrical/lucas/testing-lucas-dynamo/

How to repolarise (flash) a dynamo:[urlhttps://www.matchlessclueless.com/electrical/lucas/repolarising-lucas-dynamo/[/url]

[coline]

Thanks again everyone. Lots of helpful suggestions which I will follow up.
Sorry for any confusion "-" was not a minus, just a (confusing) dash!

Colin

[scifi]

I had problems running an LED on my C11.  It gave out a very flickering light. Maybe the internal Switch Mode Regulator was switching at the wrong time compared to the noise on the supply voltage.

Also when I tried an LED on my Royal Enfield Bullet, it just blew up, apparently REs use A.C. on the lighting circuit, to avoid overloading the rectifier.

[Derek996]

I had problems running an LED on my C11.  It gave out a very flickering light. Maybe the internal Switch Mode Regulator was switching at the wrong time compared to the noise on the supply voltage.

Also when I tried an LED on my Royal Enfield Bullet, it just blew up, apparently REs use A.C. on the lighting circuit, to avoid overloading the rectifier.

A bit odd since LEDs will work on both AC and DC systems, they only light up on the positive going half of the waveform. At higher frequencies this isn't noticed but at low frequencies they will flicker. I'm not familiar with the Enfield's lighting arrangements but it could be that, like many old British 2 strokes with direct lighting, the voltage depends on having the correct wattage bulbs. Since LEDs put virtually no load on the circuit perhaps the voltage rises to such a level that they blow. I'll have look at the Enfield lighting circuit and see if I can figure it out.

[Derek996]

I just had a look at the Enfield wiring diagram and yes, it does have AC lighting. There is an AC voltage regulator but it may not work too well without a proper load.