Triumphrat

CaptRussell · 06-20-2006, 05:41 AM

I have just got my tail light working but now the bike coughs and then dies when I put the lights on (Halogen headlight). It starts right up again when I turn them off. I am guessing my alternator isn’t putting enough volts out to run the Boyer with the extra drain on the system. It’s a new battery, (I thought the headlight might work off that). What should I try first, a lower watt bulb maybe? Thanks for any assistance.

GrandPaulZ · 06-20-2006, 09:17 AM

It could be the load. Does it stay running if the bike is revving (2,000 RPM+) ??

You might want to buy a new high output alternator, maybe a Sparx...

OzBloke · 06-20-2006, 06:25 PM

Capt,

IMHO, there are a number of things you should look at before you go to the expense of a new alternator stator/rotor.

1) make sure battery is fully charged - I know it's new, but did you bench charge it for at least 10 hours before installing?

2) check your rectifier for proper operation. Can be done with a multimeter, to test if all four diodes are operating.

3) Check voltage across battery at 1000, and 3000 RPM. at 1000 -should have around 12.5V - 13.0V, and at 3000 should be between 13.5 and 14.4V. Then check again with headlight on. Should be less that 1 volt difference.

4) if you have the original stator and rotor, maybe the rotor magnets have lost their strength over time (vibration and heat will do this to magnets), you could replace it.

5) Replace barttery with Glass Mat type (sealed maintenace free). You can fit a higher capacity battery in the same space, and they hold their charge better in the vibrating environment of an older bike.

If all this looks OK, go with GPZ's suggestion of a higher power alternator.

Pete

CaptRussell · 06-21-2006, 03:20 AM

Thanks Pete, I just checked the battery and it looks like it was 11.5v so I've got it on the charger and will try the bike again tomorrow. If this turns out to be the problem, I'll still have a bike that won't charge the battery with the lights on, or/and even have a battery drain. correct?

OzBloke · 06-21-2006, 05:34 AM

Capt,

Probably, yes. Also check the zener by checking the voltage across the battery with engine revving above 3000 rpm with all lights, indicators, etc off. Should be around 13.8V. If it goes above 14.5, get your zener checked.
If I remember correctly, the two wire alterantors put out a maximum of 9 amps at 13.8V. With a 55W halogen drawing approx 4.5A, and the coils about 1 to 2 Amps each averaged, leaves very little to run everything else and keep the battery topped up. A lot of the time the battery will be needed to provide power to operate indicators, horn, brake light, etc, so it needs to be kept in top shape. If it's low, the alternator (with lights on) can't provide enough power to keep up the battery charge sufficiently, and system voltage gradually dies down. At some point (around 10V) things like Boyer stop working.

I had similar problems. I replaced the old rectifier with a $5 20A bridge rectifier (any electronic parts store) on an L bracket, replace the standard lead acid battery (<2 years old) with a Glass Mat sealed, and haven't had a problem since, even with Boyer fitted.

See how you go with a fully charged battery, and let us know.

Pete

bonnietiler · 06-21-2006, 06:01 AM

The light switch is notorious for failing and when it does it often takes the ignition circuit with it. Try a different switch first, you may find it's as easy as that.
Cheers
BonnieT

CaptRussell · 06-23-2006, 02:45 AM

Took the old beast for a twenty mile ride today, didn't miss a beat. Battery seems well charged and tried the lights when keeping up good revs and not missing etc. Looks like I just better not go too far at night time. Thanks guys for your help :-)