Headlight bulbs blowing regularly

I'm having issues with my Z650's headlight bulbs. They keep blowing. I noticed the dipped beam had gone yesterday and changed it. The bulb lasted one ride. When I set off to come back the dipped bulb had blown again. I got back home using the main beam with an altered aim. However that also blew when I turned the bike back on to have a look at the wiring.

Any ideas what could be causing it? The headlamp has had three bulbs go in 90miles of riding? The headlight is a new one and the LED ring on it is working fine.

Is it a stock type headlight or some sort of aftermarket setup? Had it been working fine before?

I would check the battery & charging system.

Agree on checking the charging system. Could be over charging.

Is there a resistor on the LED's?
Steve

martin_csr wrote: Is it a stock type headlight or some sort of aftermarket setup? Had it been working fine before?

I would check the battery & charging system. The battery needs to be good & fully charged beforehand. After charging with a motorcycle charger, it should be 12.6+ VDC. With the engine running, the voltage should be around 14.5 VDC @ 4000 rpms. The manual has some good info on checking & charging the battery and charging system stuff.

I use a Ctek US 0.8 smart charger & VC97 digital multimeter.

Thanks I will check that. It's a brand new aftermarket one.

Nessism wrote: Agree on checking the charging system. Could be over charging.

That's my suspicion, what can cause that though?

swest wrote: Is there a resistor on the LED's?
Steve

I assume so, but it's hidden behind the scenes so I'm not 100% on that.

LED's will draw as much current as it can until it blows. The small ones have a tiny resistor soldered in the base. They might be taking all the juice the charging system can give and the head light being on the same line is getting it too. Try unplugging the LED's.
Steve

It might help to mention exactly what headlight you installed.
Over-charging would be a bad voltage regulator, most likely.

swest wrote: LED's will draw as much current as it can until it blows. The small ones have a tiny resistor soldered in the base. They might be taking all the juice the charging system can give and the head light being on the same line is getting it too. Try unplugging the LED's.
Steve

I've replaced the bulb again and looked at the circuit board inside this time and I can see some resistors on the leds.

Interestingly I had some more strange electrical issues after this ride. The trip out was fine, but on the way back the headlights came on by themselves and one of the indicators was stuck lit at first. When I got back the bulb had again blown and the rear light was also not working! I'm thinking that there is a short in the system as there are too many issues for it to just be the headlight system causing the issues,

martin_csr wrote:

Gordy wrote: ..... It's a brand new aftermarket one..

It would help to mention exactly what headlight you installed --- that's why the question was asked.
Over-charging would be a bad voltage regulator, most likely.
What year is the 650? .... the charging systems varied over the model range.

The headlight is this one here:




It's a 78 z650, the voltage regulator doesn't appear to be the standard one from the looks of it. I may just get a new one to see if that helps. I will try to get the voltmeter on the circuits to see what is going on.

A bad ground wire, with respect to the negative lead of battery and or the regulator module can cause this.
You would be quite surprised to how much voltage the charging system can generate with a bad ground.

Also, an LED is a diode and only requires between .6v and a little over 1v to work.
The small value resistor is really just to limit the current flow through the diode to 10ma to around 20ma-30ma so the diode doesn't draw too much current, overheat and blow open.
Of course if there are a lot of parallel LEDS for max brightness, then there is a higher current draw but for the same brightness, never as much as an incandescent bulb.

missionkz wrote: A bad ground wire, with respect to the negative lead of battery and or the regulator module can cause this.
You would be quite surprised to how much voltage the charging system can generate with a bad ground.

Also, an LED is a diode and only requires between .6v and a little over 1v to work.
The small value resistor is really just to limit the current flow through the diode to 10ma to around 20ma-30ma so the diode doesn't draw too much current, overheat and blow open.
Of course if there are a lot of parallel LEDS for max brightness, then there is a higher current draw but for the same brightness, never as much as an incandescent bulb.

Thanks. I think I will take a look under the tank to check for wiring issues then just replace the regulator as it's old and iffy looking anyway.

Run the bike and check the voltage. It should be frying the coils and other lights too.
Steve

Ok, I've just whipped the tank off to check for any melted cables just in case that was the issue. I cannot see any issues in the wiring there. I removed the bulb and took a multimeter to the inputs.

Dipped beam engine off: 11.5V
Full beam engine off: 11.5v

However the curious thing is that when the full beam is turned off it still registers with 2.5v going to it? Surely it should be 0v when off.

I will put the tank back on after the school run and see what the voltages are then.