Sidecar lights with LEDs is puzzling

[duTch]

 Maybe you need to include the wiring for the Speedo and pilot lights- problem may be in there ?
 Obviously the only wire to ammeter -ve is from the regulator (I've connected brake and horn to that just because) otherwise it's the kinda shit situation I normally have 
 
 

Only thing I can see is the chair / bike stop/tail wiring appears to be reversed. And the bulbs appear to be different. Or am I misunderstanding the set up?

 

[RogerSB]

Only thing I can see is the chair / bike stop/tail wiring appears to be reversed. And the bulbs appear to be different. Or am I misunderstanding the set up?

Thanks, the bike and sidecar wiring to the bulb holders are the same but the manufacturer's of bike and sidecar lights have their own particular wiring colours, i.e. bike has a standard Lucas 564 light with red and black to filament contacts and in this case I added a black for earth because there wasn't one on the light. The sidecar light is a replica Lucas 692 car light with red and green cables to filament contacts and a black earth on bulb holder. I did check which of the colours switched on the different filaments for each light, so although they have different colour cables the stop light wiring (brown cable) from bike does operate the stop light filament in both lights and the brown & green both the tail lights.

The tail/stop light bulbs are both 12V, equivalent 21/5W LEDs, positive earth but from different manufacturer's, as are the speedo and pilot light bulbs.

Thanks Dutch, I have checked the wiring to the pilot and speedo lights and as mentioned I don't have this problem with normal incandescent bulbs, it's only when I fit 'All' LEDs. I remember that Roy mentioned before that he has all LEDs on his A7 and his sidecar and that he doesn't have a problem and that he bought all his bulbs from the same place (Paul Goff).  To me it all points to the LEDs and not the wiring either on bike or sidecar and I've been wondering if the LEDs from different sources / manufacturers may somehow be causing the problem. (Edit) So I may replace all the LEDs I have with ones from Goffy and see if that sorts it. If not then the 10W incandescent can stay in the sidecar's front light, which then makes all the other lights behave.

Another strange thing is that if I leave all LEDs in place on bike and sidecar but change the bike's tail/stop bulb (in this case bought from Goffy) for a normal 21/5W incandescent bulb the sidecar's tail/stop LED doesn't come on at all . . . but then all the  other lights work as they should.   

[RDfella]

modern technology - didn't get this problem with acetylene lights. Dunno how you create a stop light, though

[Swarfcut]

 Roger, LED'S are semiconductors, and as such don't obey the well known Ohm's law for current, voltage and current. Mixing LED and tungsten bulbs means there is an imbalance of resistance and current through the various parts of the circuits. Doesn't point the finger exactly, but could account for the unexpected and mysterious things happening. With a tungsten bulb in the rear light holder, looks as if all the current is going that way as it must have a lower resistance than those parts of the circuit containing a LED. The internal resistance of different brands of LED's is probably not specified, and may not be standard between brands, causing an imbalance of current and voltage, hence differing or absent light emission.

  For the masochists out there, Kirchhoff's Law will occupy a quiet afternoon, calculating current at junctions. But whether it works for modern LED's, we need some more expert insight.

RD....A little Aldis signal lamp?

Swarfy.

[RoyC]

As you say Roger. All my LEDs came from Paul Goff including my Headlight, see below.
       
Also available with the shallower Wipac Quadoptic H4. This gives more space where there is a headlamp Nacelle & speedo cable in the way, BSA A10 etc. or a mass of wiring inside the headlight shell, Mk111 Commando.

1 x Daylighter H4 LED4K + Wipac 7.0" H4 headlight & adapter

Pt.no. H4LEDWIP £64.95 (Normal price £67.85)

It is not possible to fit the H4LED5K to Wipac Quadoptic H4s. They will however fit any other type of H4 headlight.


http://www.norbsa02.freeuk.com/goffyWhyNotLEDs.htm 

[Greybeard]

For the masochists out there, Kirchhoff's Law will occupy a quiet afternoon, calculating current at junctions.

Wow, Kirchhoffs Law! That took me back thirty years to my BT Telecommunications courses. As with almost everything else I learnt back then it was never needed.

I never forgot this rhyme: 'One over two Pi route LC, is the resonant frequency'.
f = 1 / (2π √L C)

[RogerSB]

Thank you all for your responses. I think it'll probably stay for ever as one of the worlds biggest mysteries. 

[Black Sheep]

If it's any consolation, I hired a trailer with LED lights and they wouldn't work hitched up to my -ve earth Land Rover. However, the trailer board I had to lash on instead with incandescents worked a treat. Couldn't be arsed to puzzle it out.

[RogerSB]

If it's any consolation, I hired a trailer with LED lights and they wouldn't work hitched up to my -ve earth Land Rover. However, the trailer board I had to lash on instead with incandescents worked a treat. Couldn't be arsed to puzzle it out.

Yes, it definitely is. 

[duTch]

 

modern technology - didn't get this problem with acetylene lights. Dunno how you create a stop light, though

     Chuck in an extra lump of carbide at the right time 

[RogerSB]

Found this about LEDs and their legality and it sort of rings a bell.

https://www.jlclassics.com/phdi/p1.nsf/supppages/jlc?opendocument&part=13

[berger]

you've seen the light now roger

[Greybeard]

Found this about LEDs and their legality and it sort of rings a bell.

https://www.jlclassics.com/phdi/p1.nsf/supppages/jlc?opendocument&part=13

That is a valuable piece of information. Roger, how about making a new topic in electrics just to bring this to everyone's attention?

[RoyC]

Found this about LEDs and their legality and it sort of rings a bell.

https://www.jlclassics.com/phdi/p1.nsf/supppages/jlc?opendocument&part=13

Thanks for that Roger.
Very interesting reading.

[mikeb]

I think RDfella and lawnmowerman are on the money here – either:

• The earth on the tail lamp fitting (or the bulb) is dodgy OR
• The earth on the side car is dodgy OR
• The tail lamp on the sidecar is reversed (stop <–> tail) OR
• The bulb has dodgy internal wiring – ie coming on more brightly for stop rather than having independent LEDs like they should be OR
• Can the bulbs fit the sockets more than one way? (ie rotate)

The wiring gauge has nothing to do with it – as RD says the LED current is minimal. Any reference to Kirchhoff's Laws (which one?) is only going to give you a headache and obscure simplicity.
Swarfy yes they are semiconductors with a certain forward voltage and nominal current and to achieve this have their own regulator (or worse) a fat resistor to limit the current. But lighting is not wired with bulbs in series (or should not be!) so there are no balances or imbalances to speak of.
Legally in NZ its illegal to modify the lighting in any way so putting a 12v 60W halogen in pace of a 6v 35W incandescent would require vehicle re-certifying, as would any LEDs. Ridiculous - just make sure they work well and dip properly and find a sensible vehicle tester.
I may not be helping in saying this Roger, but the solution should be easy once found. Its electricity, not space science or magic (assuming the magic smoke has not come out yet)