Battery cable came off!
#136
Guest
Posts: n/a
Re: Battery cable came off!
Michael Pardee wrote:
> I think this is getting pretty far afield. Does anybody feel the alternator
> would be stable under varying load with the battery disconnected?
>
Thanks for bringing it back, mike. I've been reading all the posts very
closely.
Anyway, as an update, no delayed effects yet, thankfully. Though I'm
not willing to repeat the "experiment" anytime soon: Seems like I have
a shorted rectifier in the alternator. (Does this mean that I'm getting
voltage spikes all the time?) I'm wondering if the battery is now
"absorbing" the spikes, so it seems to boil down again to whether the
battery is acting as a large capacitor..
Thanks again to everyone.
#137
Guest
Posts: n/a
Re: Battery cable came off!
Michael Pardee wrote:
> I think this is getting pretty far afield. Does anybody feel the alternator
> would be stable under varying load with the battery disconnected?
>
Thanks for bringing it back, mike. I've been reading all the posts very
closely.
Anyway, as an update, no delayed effects yet, thankfully. Though I'm
not willing to repeat the "experiment" anytime soon: Seems like I have
a shorted rectifier in the alternator. (Does this mean that I'm getting
voltage spikes all the time?) I'm wondering if the battery is now
"absorbing" the spikes, so it seems to boil down again to whether the
battery is acting as a large capacitor..
Thanks again to everyone.
#138
Guest
Posts: n/a
Re: Battery cable came off!
"sharx333" <emil.santos@gmail.com> wrote in message
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
#139
Guest
Posts: n/a
Re: Battery cable came off!
"sharx333" <emil.santos@gmail.com> wrote in message
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
#140
Guest
Posts: n/a
Re: Battery cable came off!
"sharx333" <emil.santos@gmail.com> wrote in message
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
#141
Guest
Posts: n/a
Re: Battery cable came off!
"sharx333" <emil.santos@gmail.com> wrote in message
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>
> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
> not willing to repeat the "experiment" anytime soon: Seems like I have
> a shorted rectifier in the alternator. (Does this mean that I'm getting
> voltage spikes all the time?) I'm wondering if the battery is now
> "absorbing" the spikes, so it seems to boil down again to whether the
> battery is acting as a large capacitor..
>
> Thanks again to everyone.
>
In my experience, yes, you can expect to be getting ripple of about 1/2 volt
to 1 volt even with the battery connected. It should be measurable with a
DVM on AC voltage setting, measuring across the battery with the engine
running. If diodes in two phases (out of the three phases most alternators
use) fail the AC voltage can be over 1 1/2 volts with the battery connected.
On an oscilloscope it looks pretty radical. With one phase out the voltage
hangs around 14 volts and drops when the bad phase is called on to put out.
With two phases out the voltage hangs around 12 volts and spikes upward.
Mike
#142
Guest
Posts: n/a
test post please ignore
On Sat, 16 Dec 2006 07:08:34 -0700, "Michael Pardee"
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
#143
Guest
Posts: n/a
test post please ignore
On Sat, 16 Dec 2006 07:08:34 -0700, "Michael Pardee"
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
#144
Guest
Posts: n/a
test post please ignore
On Sat, 16 Dec 2006 07:08:34 -0700, "Michael Pardee"
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
#145
Guest
Posts: n/a
test post please ignore
On Sat, 16 Dec 2006 07:08:34 -0700, "Michael Pardee"
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
<michaeltnull@cybertrails.com> wrote:
>I think this is getting pretty far afield. Does anybody feel the alternator
>would be stable under varying load with the battery disconnected?
>
>Mike
>
test
#146
Guest
Posts: n/a
Re: Battery cable came off!
"Michael Pardee" <michaeltnull@cybertrails.com> wrote in
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
#147
Guest
Posts: n/a
Re: Battery cable came off!
"Michael Pardee" <michaeltnull@cybertrails.com> wrote in
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
#148
Guest
Posts: n/a
Re: Battery cable came off!
"Michael Pardee" <michaeltnull@cybertrails.com> wrote in
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
#149
Guest
Posts: n/a
Re: Battery cable came off!
"Michael Pardee" <michaeltnull@cybertrails.com> wrote in
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
news:U7-dnQ-8-Lps_xnYnZ2dnUVZ_segnZ2d@sedona.net:
> "sharx333" <emil.santos@gmail.com> wrote in message
> news:1166300422.081048.241360@73g2000cwn.googlegro ups.com...
>>
>> Anyway, as an update, no delayed effects yet, thankfully. Though I'm
>> not willing to repeat the "experiment" anytime soon: Seems like I
>> have a shorted rectifier in the alternator. (Does this mean that I'm
>> getting voltage spikes all the time?) I'm wondering if the battery is
>> now "absorbing" the spikes, so it seems to boil down again to whether
>> the battery is acting as a large capacitor..
>>
>> Thanks again to everyone.
>>
>
> In my experience, yes, you can expect to be getting ripple of about
> 1/2 volt to 1 volt even with the battery connected. It should be
> measurable with a DVM on AC voltage setting, measuring across the
> battery with the engine running. If diodes in two phases (out of the
> three phases most alternators use) fail the AC voltage can be over 1
> 1/2 volts with the battery connected. On an oscilloscope it looks
> pretty radical. With one phase out the voltage hangs around 14 volts
> and drops when the bad phase is called on to put out. With two phases
> out the voltage hangs around 12 volts and spikes upward.
>
> Mike
>
>
>
Applying AC straight from one phase of the alternator's output would harm
the battery,causing excessive heating.On one-half of a cycle,the battery
would charge just like the other phase outputs,but on the 2nd half cycle,it
would discharge(thru the ALT),maybe even provide a path for damaging
currents to be drawn from the battery.It depends on whether the diode
failed open or short/leaky.
Open failure would just remove that phase winding's output,lowering the
alternator's total output current,and giving more ripple.
--
Jim Yanik
jyanik
at
kua.net
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