CBF 125 Headlight Wiring Reading 22V

[Danny_V.17]

Hi, recently I've been trying to install a new LED headlight on my CBF 125 M9 for multiple reasons (mainly as it's almost traditional for a 17 y/o) but I've been running into problems. The first bulb I tried blew after a couple of seconds of working fine, I returned and refunded it. The second bulb had much better reviews online so I went with it, fitted it, but it flickered at an unacceptable and likely illegal level. I tried my best to understand why this was and came to the conclusion it was because the headlight wiring was AC and therefore very inconsistent, (the flickering lessens at higher revs, as expected) which was unnoticeable with the old halogen but that's not the problem I'm here for. I ordered a resistor that you'd just plug inbetween the wire and the bulb, theoretically fixing the issue, but no light was coming out of the bulb at all when it was plugged in (I tried both to see if it was a fault in the part, no joy.) Then I decided to measure the voltage of the wiring to see if that was the problem, and this is where it gets interesting; on lowbeam setting with my positive probe on the battery terminal and the negative on the lowbeam connector, I was getting a reading of 22 volts, the same if I tested the high beam. Now my battery, being a 12V battery, surely shouldn't be able to output nearly as much as that?

With the resistor fitted, all 3 terminals were reading 13.7V but that's likely because it is a 9-16V resistor and it's being given more than that.

 

I'm not sure if this is a simple problem or fault in my testing but it puzzled my dad, who's been a master technician for 4 years or so.

Any and all help and advice is appreciated.

[Bender]

If its ac the lights are powered direct from the srator/charging system direct, you need to look ar reg/rec stator, if its blowing bulbs or if the original is fine your using wrong bulbs  

[Danny_V.17]

2 hours ago, Bender said:

If its ac the lights are powered direct from the srator/charging system direct, you need to look ar reg/rec stator, if its blowing bulbs or if the original is fine your using wrong bulbs  

I'm pretty sure it is ac as the original bulb gets brighter as I increase revs, and with this bulb the flickering reduces.

The original bulb was fine I'm just very concerned as to why there was a 22V reading because as far as I'm aware that'd be way too much for any bulb that size?

[Bender]

https://bikesandtravels.com/biker.aspx?ride=953

 

Have a look through that

[Danny_V.17]

On 24/09/2021 at 18:38, Bender said:

https://bikesandtravels.com/biker.aspx?ride=953

 

Have a look through that

I read through that and sat puzzled still for a while before being told that my dad stubbornly refused to beleive that it was actually receiving an AC supply, therefore measured the voltage with the voltmeter set to DC.

Now that problem has been sorted, the issue of a flickering LED is the new issue.

I've looked and looked online and asked other mechanics their opinions but I haven't been able to get a definite answer out of any of them.

As I've mentioned before, I've tried a regulator, which didn't work, and have now been suggested to try a rectifier. Any facts/ideas/opinions/other forums?

[billy sugger]

Flickering bulbs are a known symptom of a faulty reg/rec, along with the resin on the stator going brittle and breaking off the windings, (though I've no idea why that is). What are the voltage readings, taken with lights on and off? 

You should get 14.3 to 14.7volts shoeing as you rev up to 4000rpm momentarily