BMW f650 GS

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jasperthedog
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BMW f650 GS

Post by jasperthedog »

[attachment=0]20210307_135419.jpg[/attachment

Afternoon All,

Has anyone got a simple answer for my indicator problem please.

I have 3 12v bulbs as picture, all work but only the one on the right flashes.

Left
Lucas 12 v 5w just lights up, no flashing

Middle
Some Chinese brand 12v 10 watt just lights up not flashing

Right
Phillips 12v 10 watt flashes as expected.

All plugged in the same socket,

I would have expected all to flash with just the 5w being a touch dull.

Can anyone explain what's going on.

Rich.
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Dark Knight
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Re: BMW f650 GS

Post by Dark Knight »

Very interesting question that seems to put electrical theory in doubt.
The 12V 5 Watt bulb may be not drawing enough current for the circuitry to work.
As for the 10 Watt bulbs, I suggest that the 10 W bulb that does not work is not really 10 Watts and that is why it is not working.
A bit of a delay in posting this message as that music video of June Pointer in the bath just came up on the TV, it understandably stopped me in my tracks, I think most of you will know why.
bill_qaz
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Re: BMW f650 GS

Post by bill_qaz »

For the low cost of bulbs why not buy 4 new bulbs of the correct rating asper handbook and of a well known brand?
dodursley
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Re: BMW f650 GS

Post by dodursley »

Indicator bulbs are often 21w, 5w will not take enough amps to run the relay, although not all relays a current sensitive type.
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Hugh
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Re: BMW f650 GS

Post by Hugh »

Greetings Rich,

I hate electrickery :evil:

Any how I think that you need to actually measure some basic readings;

what is the voltage available to power the circuit?
what is the voltage entering the bulb?
are the earth connections good?
is the circuit actually on the bike or is it something that you have made up?
what is the resistance through each bulb?
what is the amperage flowing through each bulb when powered by the battery?

Using water as an analogy

V = voltage (in volts) = reservoir of electrical energy = header tank in the loft
I = current (in amps) = rate at which it can flow = trickle or pours out
R = resistance (in ohms) = size of the pipe the water will flow through
P = power (in watts) = will the rate and volume of water knock you off your feet

Unknown Value Formula - put your recorded figures for each bulb into the formula
Voltage V = I x R
Current I = V/R
Resistance R = V/I
Power P = V x I

What are the ratings of the flasher unit and is it designed for normal tungsten type bulbs or LED?

Unless you really want to know the answer I would probably just do as Bill says, check the manufacturers specifications and fit a set of new bulbs bought from a reliable source :lol:

TTFN

Hugh.
catcitrus
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Re: BMW f650 GS

Post by catcitrus »

The relay obviously relies on current draw to switch it--hence working correctly with a decent bulb. These days relays are electronic in the sense that they switch whatever the current draw--and are necessary because of the low current draw of LED bulb systems. You could change out the relay--but at least with the old school relay you typically know when a bulb goes down as the flashing rate changes.
Richard Simpson Mark II
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Re: BMW f650 GS

Post by Richard Simpson Mark II »

I've always 'cured' such issues when they've occurred by buying an old-school flasher relay (bi-metalic strip kind) from a motor factors or Halfords and fitting 4 x decent brand-name bulbs.
If you are unlucky enough to have an 'electronic' bike when everything is done by a canbus, then god knows.
fatowl
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Re: BMW f650 GS

Post by fatowl »

Some , usually older relays use the current to heat s bimetalic strip, which, when it gets hot, bends, and brands the circuit, allowing it to cool down. If the bulbs don't draw enough current, then the strip doesn't get hot enough, and the bulbs stay on.
jasperthedog
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Re: BMW f650 GS

Post by jasperthedog »

Big Thank you for your replies, I think it all makes sense now.

The way i see it the relay needs 10w minimum to allow switching, the Phillips being a quality bulb is fine but the Chinese copy although marked
10w is probaly making less.

All sorted now, just nice to know what the issue was.

Thanks again,

Richard.
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