Bulbs Blowing Electrical Help Needed

[Northside]

Hey guys I have an 80 650 with electronic ignition. I fully rebuilt the bike with all new wiring and a tc bros chopper harness along with a 5 lug momentary start switch, stock reg/rec, ignition box. I also have a ganged fuse box powered off the ignition lug on the switch. I fired it up yesterday for the first time and after a while my headlight got brighter and blew along with the tail light. I have 13. 8 volts while revving at the battery. I checked power at the tail light wires and its reading the same as the battery. Are the lights supposed to read a steady 12v? Its like my lights are powered thru the charging system. I also don't know why the bulbs blew and not the fuses powering them.

Any help is greatly appreciated, I have been digging around but most threads lead to the regulator and I believe mine is ok.

 

[Northside]

I found my ground was stupid loose and tightened it up. What should voltage at headlight and tail read while running and revving? Thanks

 

[mrtwowheel]

The voltage at your lights will vary, just the same as your battery voltage will vary. The voltage at the lights will probably be just a bit lower than the battery because of resistance in connections and switches. So, with a healthy battery and charging system, I'm guessing, your voltage at lights will be about 11.5 to 14.2 volts, depending on RPM and how many lights are on.

Scott

 

[mrtwowheel]

So, your bulbs are still good, just didn't light because of the bad ground?

Scott

 

[Northside]

Ok thanks for that info. Wiring was never my strong point! I noticed my headlight is also wired so on hi the low beam filament stays on also. Will this draw too much? I only have a headlight, tail light and neutral indicator for lighting. Thanks again,

 

[TwoManyXS1Bs]

...I noticed my headlight is also wired so on hi the low beam filament stays on also. Will this draw too much?

If not, it'll get too hot anyway. Mis-wired connections to the 3-lug headlight connector aren't uncommon. Usually using the wrong lug for ground, causing one of the selections (in your case, hi-beam) to drive both filaments simultaneously. Have a look at XSleo's post #4 in this thread:

http://www.xs650.com/threads/new-head-lamp.46076/#post-461173

 

[Northside]

Ok, yeah for my hi beam switch I have an on off, I need an on off on to cut the low while on hi. Makes for a great hi beam though!

 

[Paul Sutton]

I am not sure how you have wired the switches but normally the On/Off switch is first in series and supplies power to the Hi/Low switch. So if On/Off switched off the Hi/Low switch will not power the lights. If switched on then the Hi/Low switch will either power the low beam or the high beam. If you run both Hi and Low together you probably are drawing about 110W and this puts the current drain at 8 - 9 Amps so you may be close to blowing a fuse and putting a high load on the battery at idle.

With a charging circuit a typical charge voltage is approx. 14.3V. This level of voltage gives maximum charging but with minimal electrolysis of the water in the battery. At 14.7V the charging process becomes dominated by electrolysis so the acid level in the cells drops quite rapidly. Immediately after charging the battery voltage will be about 13.5V (from memory) but after a few hours this will drop off to approx. 12.6 - 12.7V which is the voltage for a fully charged lead cell battery. If you measure a voltage of 12.0V then the battery is about 50% charged:

As implied above the electric systems have to tolerate a big voltage variation when a vehicle is operating with or without engine on. If all your contacts are in top condition then you normally should not see a voltage difference of more than about 0.3V when comparing with the voltage at the battery. I once had several bad connectors in series and it dropped my voltage by approx. 1V compared to the battery (12.4V) so that my alternator field winding was too weak to give good charging around town..

 

[Northside]

Thanks for the info! All I have is a hi low switch for my headlight no on off. So it is all powered thru the one switch I need another style toggle. I rode maybe 50 miles today for the maiden voyage and all was great!