question for electrical gurus!

[weaselnoze]

i have 4 accessory lights.  im pretty sure they are 194 bulbs or similar size.  i hooked one up with positive straight to battery and neg to the chasis.  the bulb blew after about 1/2 hr of riding time.   what do i need to do for 4 of these lights?  i understand the basics like volt, amperage, ohms... etc.

[davipu]

add the appropriate resistor so it doesn't overload

[weaselnoze]

a fuse?  a fuse keeps from too many amps goin through right?

[davipu]

no a resistor, it acts like a dam to keep too much juice from going through, but dosn't blow when it overloads.

[weaselnoze]

now i've used resistors on circut boards but have no clue what these should look like or where to get them.  also how much  resistance

[davipu]

i don't know I was BSing

[weaselnoze]

ok then.  to someone who knows...

could i wire these to the open connection in the headlight?  would this solve my problem?

[weaselnoze]

bumpity.  cant ride till i fix this problemo.

[ktrim]

194 bulb can only handle 12volts.  if you hook it straight to the battery,  when it is charging you are getting 13.5 volts.  you can try a heavy duty bulb  (194hd) this may help.  or Isolate it from the battery with a relay.  you can also use a 470 ohm resistor on the postive leg of the bulb.  you can get the resistor at radio shack (usually about 99 cents for 5 or ten resistors.  that should help.  the resistor will get very hot so you will have to wrap it tape alot.   usually blowing bulbs is repeatedly is due to a bad ground or faulty socket.  move the ground to the battery also.  check to make sure the bulb fits tightly in the socket with no play.

[Rema1000]

A lightbulb is a kind of resistor.  You can plug a 60 watt bulb directly into your house power (e.g., a 20-amp circuit... 20 x 110 = 2200 watts!), and it will still only draw 60 watts, not 2200. No extra resistor is needed.

When your regulator is producing 13.5v, that voltage is connected directly to the ignition, and from there to the whole bike.  If the voltage between battery terminals is 13.5v, then so is the voltage everywhere else on the bike.  But if your regulator is producing overly-high voltage, that will shorten bulb life.  You might want to hook a meter to your battery, and check the voltage after start-up; and play around with the throttle, and see how the voltage responds.  Repeat tests when the engine is fully warmed-up.

On my bike, when the R/R went south, I was getting 16v-17v at idle... and the voltage came down as RPMs climbed!  I burned-out 3 headlights (and one battery) that summer.

[John Bates]

...............  im pretty sure they are 194 bulbs or similar size. ................

If they are not 194s then they could be for a lower voltage which would explain the short life.

If they are 194s then they shouldn't burn out that quickly, you may have an over volatage condition as Rema suggests.  A resistor is not required with a 194 bulb.

[starwalt]

i don't know I was BSing

davipu, you were mostly correct though. The resistor would limit the current (amperage, amps) that passes through the lamp, but it would also reduce the amount of light the lamp produces. Lamps are rated at a voltage(max) and a current (max). Exceeding either reduces life span.

The resistor analogy is also correct. It is the power the lamp wastes, in the form of heat to produce light, that makes the rating value in watts.

Even though a lamp is rated at a certain voltage, it may have a duty cycle rating...although in this case, I believe the lamp should have lasted longer than the 1/2 hour you report. Here is a link to your 194 bulb.  Notice that it rates the lamp with voltage and power in WW...I think they mean "working watts". That's a new phrase to me, but the math works out to .27 amps when using 14V.  3.78WW = 14V x .27A

So either your battery was way over 14V (was the engine running?) or the current was way over .27 amps or both. Another possibility is the bulb was used or bad.

[weaselnoze]

ok this is almost too much for me.  i need a dictionary and a calculator.   :x  

so when the bike is charging (over a certain rpm as discussed in another topic), its putting out 13.5 volts?  that means 13.5 volts are going to all the bulbs, electronics of the bike?  theoretically, wiring it direct to the battery shouldnt be a problem right?  im assuming my bike has no electrical issues and that i did all my wiring correctly with good grounds etc.  

back to the extra connection in the headlamp... is this a good power source?

one more thing.  im hooking up multiple lights here.  should the positive connection be direct from each light to the source or can it go from light to light then the source ?

[The Buddha]

Well I'd run 2 bulbs in series ... and for resistor you want a wire wound one, the regular crap semi conductor ones wont do ...
And about dictionary and claculator ... add a electrical design book and you need all those before you talk to starwalt ...  :lol:  ... You didn't know that ...
Cool.
Srinath.

[John Bates]

ok this is almost too much for me.  i need a dictionary and a calculator.   :x  

so when the bike is charging (over a certain rpm as discussed in another topic), its putting out 13.5 volts?  that means 13.5 volts are going to all the bulbs, electronics of the bike?

Correct. Actually the acceptable voltage range is 13.5 - 15.5 V.

theoretically, wiring it direct to the battery shouldnt be a problem right?

Correct.

back to the extra connection in the headlamp... is this a good power source?

Yes it is a good power source.  It is switched on and off by the ignition switch.

one more thing.  im hooking up multiple lights here.  should the positive connection be direct from each light to the source or can it go from light to light then the source ?

It can go either way, just so all the positive wires are hooked together at some point and all the negative wires are hooked together.

[weaselnoze]

so if i run all the power from the extra connection in the headlight, i shouldnt have to add any resistors, fuses or anything like that?  

bates, you said all the neg wires hooked together.  cant i just ground each one near the light?

[John Bates]

so if i run all the power from the extra connection in the headlight, i shouldnt have to add any resistors, fuses or anything like that?  

Correct if you use the same size wire as the existing wire. If your new wire is smaller than the existing wire then you should place a fuse in line with the new main positive wire branch.

bates, you said all the neg wires hooked together.  cant i just ground each one near the light?

Yes, however it may not give you the best electrical connection.

[weaselnoze]

now say i end up gettin a fuse.  how do i determine what size?

[John Bates]

now say i end up gettin a fuse.  how do i determine what size?

the fuse protects the wire

16 awg. wire, 7.5 amp fuse
14 awg. wire, 15 amp fuse

[weaselnoze]

great! thanks bates! you've been a big help as always  :mrgreen: