measuring peak voltage

--
I\'d do something like this: (View in Courier)


+12V>------+----[1N4002>]--+---------------+
           |               |               | 
         [LAMP]          [1µF]   [PEAK HOLD VOLTMETER]
           |               |               | 
GND>-------+---------------+---------------+

Any spikes on the 12V line will charge the capacitor quickly, but it
will discharge slowly through the voltmeter\'s internal resistance
(10 megohms for nearly all DVMs)allowing the DVM to acquire it
before it decays significantly.

It might be easier and cheaper to simply fix the problem than to analyze it. A

15 volt zener diode at the bulb would surely do it. Higher voltage spikes don't strike me as a likely cause of bulb failure. Vibration and bulb design are more likely candidates. What about an LED replacement for the incandescent bulb(s)?

Chuck

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for a

faulty

it. A 15 volt zener diode at the bulb would surely do it. Higher voltage spikes don't strike me as a likely cause of bulb failure. Vibration and bulb design are more likely candidates. What about an LED replacement for the incandescent bulb(s)?

Hi Chuck, thanks for that - we are having a nightmare with this ! the problem is occuring on a whole batch of bikes from one specific manufacturer, they seem to have in common that they all have the same voltage regulator and similar wiring loom. on some of the bikes the bulbs will blow every 15 or 20 mins.... on a test bike i've tried LED bulbs and they seem to fix the problem except for the headlight bulb for which i presume there is no LED possible replacement... to try to eliminate vibration and bulb quality as the possible cause i've previously tried physically soldering a halogen headlight bulb directly into the wiring and mounting it solely (but securely) with silicone... this lasted a little longer but still blew after a while - i can only think it is the regulator... the regulators charge the battery at 14.8 volts - other bike regulators seem to be more like 14.0... do you think 14.8 is too high? how would the 15 volt zener diode work ? many thanks again, andy

Either the bulbs aren't rated for the voltage or the charging voltage is too high. Spikes would be way down on the possibles list.

If the connection to the battery is unreliable that will make the voltage go high and burn out the lamps.

Try good quality bulbs. If they fail, you need to look at the regulator or the wiring. How many amps is the regulator charging at?

thanks john, that makes perfect sense - even to me ! i only have a cheap multimeter with no peak hold - time to upgrade i think..

do you think that one will do the job ? looks as if it has peak hold - do you think the pc software and interface will let me display a voltage graph whilst i go for a ride? any other recommendations ? thanks again, andy

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Dunno... the manual stops at page 24.

check the battery connection. if you lose the connection the alternator will run wild. make sure the accessory line to th rest of the bike is secure from the battery connection. it's possible the alternator is connected to the battery higher up in the circuit. a bad module plug can also cause this.

--
"I\'m never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Hello Andy,

The zener was suggested to clip the peaks (if any). Bulbs should not blow every

15 or 20 minutes, of course. Someone suggested ensuring a tight battery connection: that is vital. I would say that 14.8 volts (I assume you have measured this at idle and at some moderate engine rpms) is probably on the high side, but I would still not expect the results you're seeing.

Is the regulator electronic or mechanical? What kind of bike is it (just curious).

Chuck

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"Andy C"

**Consider that the bikes have been fitted with defective batteries that are vibration sensitive.

Under vibration, the internal cell to cell connections come apart.

Explains your observed symptoms.

Try replacing a few.

....... Phil

i hadn't thought of this.... so if the batteries are defective (we have had problems with defective batteries before) the alternator could run 'wild' as in jamie's post above... why would the regulator not be able to cope with the battery not connected though ? the regulator has 2 wires going in (approx 50volts ac) and has 2 wires going out (12v dc) would it still not keep the circuit regulated to ~14volts with the battery disconnected? cheers, andy

"Andy C"

** As several other posters have indicated, electronic regulators cannot function with a missing or defective battery.

Just a fact.

....... Phil

It's possible. The regulator has limits on what it can control - works OK with a good battery and wiring, but what happens at no load? It may send out brief pulses at 50 volts!

The battery is like a big capacitor with a smallish resistor inside. Without it, the alternator output is going to look allot like the output of a bench power supply would without it's internal caps. Most linear regulators need a cap and a small load to work right, otherwise they make nice oscillators. ;-)

ok, thanks everyone - i have plenty of leads to work with now ! andy

???

can you post a schenatic showing the interconnects?

is this a permanent magnet altenator?

are the lights DC powered?

Bye. Jasen

hi jasen, i'll post a wiring diagram ! might not be able to until monday tho thanks, andy