# measuring peak voltage

A

#### Andy C

Jan 1, 1970
0
hi there,
we have a batch of voltage regulators for motorcycles which are meant to
regulate the battery charging voltage to approx 14volts max... i suspect
they are occasionally putting out 'spikes' of higher voltage which keeps
blowing bulbs on the bikes they are fitted to...
can anyone think of an inexpensive way (or already available kit or
instrument perhaps) whereby we can fit something to a bike... take it for a
ride... and it will record the peak voltage so we can prove they are faulty
?
many thanks !
andy

J

#### John Fields

Jan 1, 1970
0
hi there,
we have a batch of voltage regulators for motorcycles which are meant to
regulate the battery charging voltage to approx 14volts max... i suspect
they are occasionally putting out 'spikes' of higher voltage which keeps
blowing bulbs on the bikes they are fitted to...
can anyone think of an inexpensive way (or already available kit or
instrument perhaps) whereby we can fit something to a bike... take it for a
ride... and it will record the peak voltage so we can prove they are faulty
?

---
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.

C

#### chuck

Jan 1, 1970
0
Andy said:
hi there,
we have a batch of voltage regulators for motorcycles which are meant to
regulate the battery charging voltage to approx 14volts max... i suspect
they are occasionally putting out 'spikes' of higher voltage which keeps
blowing bulbs on the bikes they are fitted to...
can anyone think of an inexpensive way (or already available kit or
instrument perhaps) whereby we can fit something to a bike... take it for a
ride... and it will record the peak voltage so we can prove they are faulty
?
many thanks !
andy

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

A

#### Andy C

Jan 1, 1970
0
hi there,
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)?

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

H

#### Homer J Simpson

Jan 1, 1970
0
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.

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?

A

#### Andy C

Jan 1, 1970
0
John Fields said:
hi there,
we have a batch of voltage regulators for motorcycles which are meant to
regulate the battery charging voltage to approx 14volts max... i suspect
they are occasionally putting out 'spikes' of higher voltage which keeps
blowing bulbs on the bikes they are fitted to...
can anyone think of an inexpensive way (or already available kit or
instrument perhaps) whereby we can fit something to a bike... take it for
a
ride... and it will record the peak voltage so we can prove they are
faulty
?

---
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.

thanks john, that makes perfect sense - even to me !
i only have a cheap multimeter with no peak hold - time to upgrade i think..
http://www.maplin.co.uk/module.aspx?ModuleNo=34800&doy=22m3
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

J

#### John Fields

Jan 1, 1970
0
John Fields said:
hi there,
we have a batch of voltage regulators for motorcycles which are meant to
regulate the battery charging voltage to approx 14volts max... i suspect
they are occasionally putting out 'spikes' of higher voltage which keeps
blowing bulbs on the bikes they are fitted to...
can anyone think of an inexpensive way (or already available kit or
instrument perhaps) whereby we can fit something to a bike... take it for
a
ride... and it will record the peak voltage so we can prove they are
faulty
?

---
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.

thanks john, that makes perfect sense - even to me !
i only have a cheap multimeter with no peak hold - time to upgrade i think..
http://www.maplin.co.uk/module.aspx?ModuleNo=34800&doy=22m3
do you think that one will do the job ?

J

#### Jamie

Jan 1, 1970
0
Andy said:
for a

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
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.

P

#### Phil Allison

Jan 1, 1970
0
"Andy C"
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....

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

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

Try replacing a few.

........ Phil

C

#### chuck

Jan 1, 1970
0
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

A

#### Andy C

Jan 1, 1970
0
**Consider that the bikes have been fitted with defective batteries that
are
vibration sensitive.

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

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

P

#### Phil Allison

Jan 1, 1970
0
"Andy C"
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?

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

Just a fact.

........ Phil

H

#### Homer J Simpson

Jan 1, 1970
0
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?

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!

A

#### Anthony Fremont

Jan 1, 1970
0
Homer said:
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. ;-)

A

#### Andy C

Jan 1, 1970
0
Anthony Fremont said:
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

J

#### jasen

Jan 1, 1970
0
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?

???

can you post a schenatic showing the interconnects?

is this a permanent magnet altenator?

are the lights DC powered?

Bye.
Jasen

A

#### Andy C

Jan 1, 1970
0
jasen said:
???

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

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