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[Gaffer64]

Hi All,

I have really fast indicators all are working, but now flashing very fast any ideas.

Cheers

Mike

[papasmurf]

The flasher relay and the wattage of the bulbs does not match.

[Scalyback]

Maybe put in 10W instead of 21W? Otherwise, the relay could have gone up the creek.

[ChrisD]

Gaffer64. I also wanted the brighter flashers on my 1996 500cc iron barrel. I fitted 21W bulbs in place of the 10W standard, didn't touch the speedo idiot light and fitted one of several car flasher units rated to 50W. They flash just fine now and only take about half-a second longer to start. I used several car flasher units because they regularly failed - I am convinced it was the vibration, but now I've found a sealed 50W one that has held up for the past year. No problem with charging although the ammeter does go berserk when I switch them on, waving at me as if I care.
Cheers, ChrisD

[jefrs]

Is this a new fault? The flashes were correct before? What was changed before this happened?



A flasher relay will run fast if a bulb blows. The bulbs are wired in parallel so if one blows open-circuit the resistive load goes up (doubles). High power bulbs have less resistance &vv (Ohm's Law). If you have fitted low power bulbs, the relay will flash too fast; a pair of 10W bulbs have more resistance than a single 21W which would cause fast flashing. A faulty bulb may produce the same effect. Also check for high resistance (corroded) connectors, pulling connectors off and on again is enough to clean contacts. Check fuses for corrosion, they can turn into resistors, do any feel hot? Probably also worth check battery volts are at least 12.5V no-load, 'cos if the volts go down high power bulbs become low power bulbs and the same stuff happens.



21W bulb about 6ohm each, two in parallel 3ohm, if one blows we get 6ohm and it flashes too fast

10W bulb about 12ohm each, two in parallel 6ohm, see above.



And yeah, it could be the relay ...

[Thack]

Have you fitted LED bulbs by any chance?

[Gaffer64]

Hi All,

Many thanks for the help. I did fit our hosts 23 watt flasher unit and indicator bulbs and all were working fine, then the flasher unit inside lost its connection. I picked up a car indicator flasher unit and all working fine, but just towards the end of my two day trip, the indicators started to flash faster, but all still work.

Any help?

Cheers Mike

[jefrs]

Assuming you have a relay flasher rather than solid state

- check relay connections, unplug and replace

- remove and test each bulb on an ohm meter

- visually inspect each bulb connection for corrosion

- check no-load battery volts is above 12.5VDC

- check each wiring connection for corrosion, especially tail unit.

- if all of theses are good the flash unit has probably gone, swap it out for another



If solid state then have a look to see if there is a rate control adjuster screw



Hope that helps

[Dennis C]

Jeff I am confused again.

"The bulbs are wired in parallel so if one blows open-circuit the resistive load goes up (doubles)"

"21W bulb about 6ohm each, two in parallel 3ohm, if one blows we get 6ohm and it flashes too fast
10W bulb about 12ohm each, two in parallel 6ohm"

Now I have spent my entire working life in electronics and I always thought that the lower the resistance the greater the load, of course the maximum load is a short circuit, zero ohms. It must have changed since I retired.

[jefrs]

DennisC - sorry, what? Resistance is load, more resistance is a bigger load, Ohm's Law. E=I/R. P=E^2/R. That tells us it takes more volts to shove the same current through a bigger resistance, a bigger weight to lift, more load. P=E*R. A low resistance will dissipate more power at same voltage; that's probably where our old brains are going in opposite directions, current and power. I did say resistive-load to avoid confusion with power because 'load' may also apply to the power dissipated.

The 23W bulbs have a lower resistance than 10W bulbs. The indicator bulb pairs are each wired in parallel, two on the left and two on the right. Wiring in parallel will halve the resistance (because they're the same), so if one blows open-circuit, the load is a single bulb.

I did use heavy handed back-of-beer-mat rounding, it gets nice round numbers

23W bulb = 23 = 12^2/R thus R = 144/23 = 6.260ohm = 6ohm

10W bulb, R = 144/10 = 14.4ohm = 14ohm, so two in parallel is 7ohm. That's about the same as one 23W bulb

23W bulbs in parallel is 3ohm but if one blows we have 6ohm and the flasher runs fast.