Home » Public Forums » GMCnet » [GMCnet] RegardingAlternator not charging battery missing info
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| Re: [GMCnet] RegardingAlternator not charging battery missing info [message #358891 is a reply to message #358886] |
Thu, 24 September 2020 01:09   |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Hi Faye. Ken B. here.
I will try to help get you started but I am leaving in the morning and will be out of Internet access for about 3 days. There are plenty of others that can continue to help.
It sounds like others have thrown a few parts at this and not done the diagnosis first. Lots things could be wrong but us remotely saying replace this or that is just guessing.
First I would verify that the meter they are using is good. Put it across one of the batteries and read the voltage. Is it somewhere around 12 volts?
Second Next move the negative meter lead to the aluminum plate that isolator is mounted on (underneath the passenger hood) and leave the positive lead on the battery positive terminal. Does it read the same around 12 volts? If both of the above are true then for all future readings while shooting this problem you can use the aluminum plate for the negative reference of the meter and probe with the positive lead.
Third I would next probe the top terminal and the bottom terminal of the isolator with the positive meter lead and see what voltages are there. These terminals are the engine and house battery readings. If they are very low then wiggle the leads a bit where there are connected and see if one of the the leads is not making a good connection. Once you are sure that you have a good reading from both of them we can decide what to do next. A fully charged battery should read between 12.6 and 12.8 volts. If it reads down in the 12.0 or so range that battery is almost fully discharged.
Fourth If you can start the GMC then start it and read the voltage on the center terminal of the isolator. This is the output of the Alternator. It should read in the 14.7 volt range. If it is good, then read the upper and lower isolator terminals again with the engine still running. They should both be around 14.0 volts.
So please fill in the following voltage readings and one of the other guys here help you from there.
_____ Volts across the engine battery without the engine running
_____ Volts at upper isolator terminal without the engine running
_____ Volts at lower isolator terminal without the engine running
_____ Volts at center isolator terminal without the engine running
_____ Volts at upper isolator terminal with the engine running
_____ Volts at lower isolator terminal with the engine running
_____ Volts at center isolator terminal with the engine running
With the above information someone here will tell what direction to head next.
If no one helps call my cell phone (two one nine) 263 8 one seven 4.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] RegardingAlternator not charging battery missing info [message #358895 is a reply to message #358892] |
Thu, 24 September 2020 09:05 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Burt and Faye curtis wrote on Thu, 24 September 2020 02:28Ken,
Thank you for your offer. Here are the missing numbers, at least most of them:
Not sure. Volts across the engine battery without the engine running
Engine would not start unless using the bat boost as was too low. Trickle charger overnight would allow for a start. Will get that measurement.
2 Volts at upper isolator terminal without the engine running
2 Volts at lower isolator terminal without the engine running
0 Volts at center isolator terminal without the engine running
2 Volts at upper isolator terminal with the engine running
2 Volts at lower isolator terminal with the engine running
0 Volts at center isolator terminal with the engine running
They had bought a multimeter at NAPA and that is what we were using. Will drop off another to check that one's readings.
0 volts at stud on alternator with the engine running
0 volts for larger of two wires in shared plastic connector with engine running larger white or yellow (?) wire
2 Volts for smaller wire of those two with engine running green or brown (?) wire
Faye,
Between KenB and Terry I am sure that this will get figured out. Right now, the data you supplied does not make any sense unless:
The meter is bad (real bad).
The techniques used is real wrong. (This is not a criticism, but there maybe some misunderstanding here.
I am not going to try to replace the two you have on the line here, but I am going to suggest that you not try to use the body of the isolator as a ground. For what you need to do, I suggest that (when you have a good meter) you try to find a good place to shove the negative (black) probe so it contacts the aluminum plate and just leave it there. This will do well for all the diagnostics under the right hood.
Then, try to fill in KenB's list again. One significant digit is good (12.1V), but if the meter will do it, two (12.18) will be better.
I am going to be really busy all day, but I will look in when I come up for air and see if Ken and Terry are back and doing any good.
At this time, I am going to offer the experience that If the battery switch is for the main engine start battery and it got opened with the engine running, that CAN damage the alternator.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] RegardingAlternator not charging battery missing info [message #358899 is a reply to message #358892] |
Thu, 24 September 2020 09:49 |
Burt and Faye curtis
Messages: 256
Registered: June 2012
Karma: 4
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Senior Member |
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So stopped by this morning to confirm readings with a different
multimeter. The house and staring batteries were being charged during the
night via shore power and trickle charger plugged into cig lighter. They
both read 12.98 volts currently.
12. 98 v from top stud to ground
12.98 v from lower to ground
0 v from center to ground
With engine running
12.98 v from top to ground
12.98 v from lower to ground
1.26 v from center to ground
Both meters samish. Second is digital, first is swing needle.
On Wed, Sep 23, 2020, 11:28 PM Burt and Faye curtis <
curtisunlimitedbandf@gmail.com> wrote:
> Ken,
> Thank you for your offer. Here are the missing numbers, at least most off
> them:
>
> Not sure. Volts across the engine battery without the engine running
> Engine would not start unless using the bat boost as was too low. Trickle
> charger overnight would allow for a start. Will get that measurement.
> 2 Volts at upper isolator terminal without the engine running
> 2 Volts at lower isolator terminal without the engine running
> 0 Volts at center isolator terminal without the engine running
>
> 2 Volts at upper isolator terminal with the engine running
> 2 Volts at lower isolator terminal with the engine running
> 0 Volts at center isolator terminal with the engine running
>
> They had bought a multimeter at NAPA and that is what we were using. Will
> drop off another to check that one's readings.
>
> 0 volts at stud on alternator with the engine running
> 0 volts for larger of two wires in shared plastic connector with engine
> runninglarger white or yellow (?) wire
> 2 Volts for smaller wire of those two with engine running green or brown
> (?) wire
>
> On Wed, Sep 23, 2020 at 11:10 PM Ken Burton via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Hi Faye. Ken B. here.
>>
>> I will try to help get you started but I am leaving in the morning and
>> will be out of Internet access for about 3 days. There are plenty of others
>> that can continue to help.
>>
>> It sounds like others have thrown a few parts at this and not done the
>> diagnosis first. Lots things could be wrong but us remotely saying replace
>> this or that is just guessing.
>>
>> First I would verify that the meter they are using is good. Put it
>> across one of the batteries and read the voltage. Is it somewhere around 12
>> volts?
>>
>> Second Next move the negative meter lead to the aluminum plate that
>> isolator is mounted on (underneath the passenger hood) and leave the
>> positive lead
>> on the battery positive terminal. Does it read the same around 12
>> volts? If both of the above are true then for all future readings while
>> shooting
>> this problem you can use the aluminum plate for the negative reference of
>> the meter and probe with the positive lead.
>>
>> Third I would next probe the top terminal and the bottom terminal of
>> the isolator with the positive meter lead and see what voltages are there.
>> These terminals are the engine and house battery readings. If they are
>> very low then wiggle the leads a bit where there are connected and see if
>> one
>> of the the leads is not making a good connection. Once you are sure that
>> you have a good reading from both of them we can decide what to do next. A
>> fully charged battery should read between 12.6 and 12.8 volts. If it
>> reads down in the 12.0 or so range that battery is almost fully discharged.
>>
>> Fourth If you can start the GMC then start it and read the voltage on
>> the center terminal of the isolator. This is the output of the Alternator.
>> It should read in the 14.7 volt range. If it is good, then read the
>> upper and lower isolator terminals again with the engine still running.
>> They
>> should both be around 14.0 volts.
>>
>> So please fill in the following voltage readings and one of the other
>> guys here help you from there.
>>
>> _____ Volts across the engine battery without the engine running
>> _____ Volts at upper isolator terminal without the engine running
>> _____ Volts at lower isolator terminal without the engine running
>> _____ Volts at center isolator terminal without the engine running
>>
>> _____ Volts at upper isolator terminal with the engine running
>> _____ Volts at lower isolator terminal with the engine running
>> _____ Volts at center isolator terminal with the engine running
>>
>> With the above information someone here will tell what direction to head
>> next.
>>
>> If no one helps call my cell phone (two one nine) 263 8 one seven 4.
>>
>> Ken B.
>> --
>> Ken Burton - N9KB
>> 76 Palm Beach
>> Hebron, Indiana
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
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| Re: [GMCnet] RegardingAlternator not charging battery missing info [message #358902 is a reply to message #358895] |
Thu, 24 September 2020 10:02 |
Burt and Faye curtis
Messages: 256
Registered: June 2012
Karma: 4
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Senior Member |
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Matt,
Think you might have misunderstood. We are using the aluminum plate for
ground for under hood readings. We were using the alternator body for one
ground check for readings from the stud (and other wire connectors)
directly on the alternator and then also using the engine block for another
reading.
Fay
On Thu, Sep 24, 2020, 7:06 AM Matt Colie via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Burt and Faye curtis wrote on Thu, 24 September 2020 02:28
>> Ken,
>> Thank you for your offer. Here are the missing numbers, at least most
> of them:
>>
>> Not sure. Volts across the engine battery without the engine running
>> Engine would not start unless using the bat boost as was too low.
> Trickle charger overnight would allow for a start. Will get that
> measurement.
>> 2 Volts at upper isolator terminal without the engine running
>> 2 Volts at lower isolator terminal without the engine running
>> 0 Volts at center isolator terminal without the engine running
>>
>> 2 Volts at upper isolator terminal with the engine running
>> 2 Volts at lower isolator terminal with the engine running
>> 0 Volts at center isolator terminal with the engine running
>>
>> They had bought a multimeter at NAPA and that is what we were using.
> Will drop off another to check that one's readings.
>>
>> 0 volts at stud on alternator with the engine running
>> 0 volts for larger of two wires in shared plastic connector with engine
> running larger white or yellow (?) wire
>> 2 Volts for smaller wire of those two with engine running green or
> brown (?) wire
>
> Faye,
>
> Between KenB and Terry I am sure that this will get figured out. Right
> now, the data you supplied does not make any sense unless:
> The meter is bad (real bad).
> The techniques used is real wrong. (This is not a criticism, but there
> maybe some misunderstanding here.
> I am not going to try to replace the two you have on the line here, but I
> am going to suggest that you not try to use the body of the isolator as a
> ground. For what you need to do, I suggest that (when you have a good
> meter) you try to find a good place to shove the negative (black) probe so
> it
> contacts the aluminum plate and just leave it there. This will do well
> for all the diagnostics under the right hood.
>
> Then, try to fill in KenB's list again. One significant digit is good
> (12.1V), but if the meter will do it, two (12.18) will be better.
>
> I am going to be really busy all day, but I will look in when I come up
> for air and see if Ken and Terry are back and doing any good.
>
> At this time, I am going to offer the experience that If the battery
> switch is for the main engine start battery and it got opened with the
> engine
> running, that CAN damage the alternator.
>
> Matt
>
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL,
> GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum
> Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
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Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] RegardingAlternator not charging battery missing info [message #358905 is a reply to message #358899] |
Thu, 24 September 2020 10:48 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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With the engine running AND if alternator is working correctly,
the voltage on the center terminal should be very close to 13.5
Volts (+/- .1 Volt)!
D C "Mac" Macdonald
Amateur Radio K2GKK
Since 30 November '53
USAF and FAA, Retired
Member GMCMI & Classics
Oklahoma City, OK
"The Money Pit"
TZE166V101966
'76 ex-Palm Beach
k2gkk + hotmail dot com
________________________________
From: Gmclist on behalf of Burt and Faye curtis via Gmclist
Sent: Thursday, September 24, 2020 09:49
To: gmclist@list.gmcnet.org
Cc: Burt and Faye curtis
Subject: Re: [GMCnet] RegardingAlternator not charging battery missing info
So stopped by this morning to confirm readings with a different
multimeter. The house and staring batteries were being charged during the
night via shore power and trickle charger plugged into cig lighter. They
both read 12.98 volts currently.
12. 98 v from top stud to ground
12.98 v from lower to ground
0 v from center to ground
With engine running
12.98 v from top to ground
12.98 v from lower to ground
1.26 v from center to ground
Both meters samish. Second is digital, first is swing needle.
On Wed, Sep 23, 2020, 11:28 PM Burt and Faye curtis <
curtisunlimitedbandf@gmail.com> wrote:
> Ken,
> Thank you for your offer. Here are the missing numbers, at least most off
> them:
>
> Not sure. Volts across the engine battery without the engine running
> Engine would not start unless using the bat boost as was too low. Trickle
> charger overnight would allow for a start. Will get that measurement.
> 2 Volts at upper isolator terminal without the engine running
> 2 Volts at lower isolator terminal without the engine running
> 0 Volts at center isolator terminal without the engine running
>
> 2 Volts at upper isolator terminal with the engine running
> 2 Volts at lower isolator terminal with the engine running
> 0 Volts at center isolator terminal with the engine running
>
> They had bought a multimeter at NAPA and that is what we were using. Will
> drop off another to check that one's readings.
>
> 0 volts at stud on alternator with the engine running
> 0 volts for larger of two wires in shared plastic connector with engine
> runninglarger white or yellow (?) wire
> 2 Volts for smaller wire of those two with engine running green or brown
> (?) wire
>
> On Wed, Sep 23, 2020 at 11:10 PM Ken Burton via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> Hi Faye. Ken B. here.
>>
>> I will try to help get you started but I am leaving in the morning and
>> will be out of Internet access for about 3 days. There are plenty of others
>> that can continue to help.
>>
>> It sounds like others have thrown a few parts at this and not done the
>> diagnosis first. Lots things could be wrong but us remotely saying replace
>> this or that is just guessing.
>>
>> First I would verify that the meter they are using is good. Put it
>> across one of the batteries and read the voltage. Is it somewhere around 12
>> volts?
>>
>> Second Next move the negative meter lead to the aluminum plate that
>> isolator is mounted on (underneath the passenger hood) and leave the
>> positive lead
>> on the battery positive terminal. Does it read the same around 12
>> volts? If both of the above are true then for all future readings while
>> shooting
>> this problem you can use the aluminum plate for the negative reference of
>> the meter and probe with the positive lead.
>>
>> Third I would next probe the top terminal and the bottom terminal of
>> the isolator with the positive meter lead and see what voltages are there.
>> These terminals are the engine and house battery readings. If they are
>> very low then wiggle the leads a bit where there are connected and see if
>> one
>> of the the leads is not making a good connection. Once you are sure that
>> you have a good reading from both of them we can decide what to do next. A
>> fully charged battery should read between 12.6 and 12.8 volts. If it
>> reads down in the 12.0 or so range that battery is almost fully discharged.
>>
>> Fourth If you can start the GMC then start it and read the voltage on
>> the center terminal of the isolator. This is the output of the Alternator.
>> It should read in the 14.7 volt range. If it is good, then read the
>> upper and lower isolator terminals again with the engine still running.
>> They
>> should both be around 14.0 volts.
>>
>> So please fill in the following voltage readings and one of the other
>> guys here help you from there.
>>
>> _____ Volts across the engine battery without the engine running
>> _____ Volts at upper isolator terminal without the engine running
>> _____ Volts at lower isolator terminal without the engine running
>> _____ Volts at center isolator terminal without the engine running
>>
>> _____ Volts at upper isolator terminal with the engine running
>> _____ Volts at lower isolator terminal with the engine running
>> _____ Volts at center isolator terminal with the engine running
>>
>> With the above information someone here will tell what direction to head
>> next.
>>
>> If no one helps call my cell phone (two one nine) 263 8 one seven 4.
>>
>> Ken B.
>> --
>> Ken Burton - N9KB
>> 76 Palm Beach
>> Hebron, Indiana
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
>
_______________________________________________
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Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: [GMCnet] RegardingAlternator not charging battery missing info [message #358908 is a reply to message #358899] |
Thu, 24 September 2020 11:41 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
|
Senior Member |
|
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Faye,
That last set of readings looks good. That center-to-ground reading says
the alternator's not putting out. Now, it's important to measure the
voltage right at the alternator. That's the single big wired bolted to the
lower back side of it -- the other wires plug in, not bolted on. Measure
from that stud&nut to the aluminum of the alternator housing. If it's not
around 14 volts (will probably be at/near the 1.2 VDC at the center
terminal), the alternator's bad.
Ken H.
On Thu, Sep 24, 2020 at 10:50 AM Burt and Faye curtis via Gmclist <
gmclist@list.gmcnet.org> wrote:
> So stopped by this morning to confirm readings with a different
> multimeter. The house and staring batteries were being charged during the
> night via shore power and trickle charger plugged into cig lighter. They
> both read 12.98 volts currently.
> 12. 98 v from top stud to ground
> 12.98 v from lower to ground
> 0 v from center to ground
>
> With engine running
> 12.98 v from top to ground
> 12.98 v from lower to ground
> 1.26 v from center to ground
>
> Both meters samish. Second is digital, first is swing needle.
>
> On Wed, Sep 23, 2020, 11:28 PM Burt and Faye curtis curtisunlimitedbandf@gmail.com> wrote:
>
>> Ken,
>> Thank you for your offer. Here are the missing numbers, at least most
> off
>> them:
>>
>> Not sure. Volts across the engine battery without the engine running
>> Engine would not start unless using the bat boost as was too low. Trickle
>> charger overnight would allow for a start. Will get that measurement.
>> 2 Volts at upper isolator terminal without the engine running
>> 2 Volts at lower isolator terminal without the engine running
>> 0 Volts at center isolator terminal without the engine running
>>
>> 2 Volts at upper isolator terminal with the engine running
>> 2 Volts at lower isolator terminal with the engine running
>> 0 Volts at center isolator terminal with the engine running
>>
>> They had bought a multimeter at NAPA and that is what we were using. Will
>> drop off another to check that one's readings.
>>
>> 0 volts at stud on alternator with the engine running
>> 0 volts for larger of two wires in shared plastic connector with engine
>> runninglarger white or yellow (?) wire
>> 2 Volts for smaller wire of those two with engine running green or
> brown
>> (?) wire
>>
>> On Wed, Sep 23, 2020 at 11:10 PM Ken Burton via Gmclist > gmclist@list.gmcnet.org> wrote:
>>
>>> Hi Faye. Ken B. here.
>>>
>>> I will try to help get you started but I am leaving in the morning and
>>> will be out of Internet access for about 3 days. There are plenty of
> others
>>> that can continue to help.
>>>
>>> It sounds like others have thrown a few parts at this and not done the
>>> diagnosis first. Lots things could be wrong but us remotely saying
> replace
>>> this or that is just guessing.
>>>
>>> First I would verify that the meter they are using is good. Put it
>>> across one of the batteries and read the voltage. Is it somewhere
> around 12
>>> volts?
>>>
>>> Second Next move the negative meter lead to the aluminum plate that
>>> isolator is mounted on (underneath the passenger hood) and leave the
>>> positive lead
>>> on the battery positive terminal. Does it read the same around 12
>>> volts? If both of the above are true then for all future readings while
>>> shooting
>>> this problem you can use the aluminum plate for the negative reference
> of
>>> the meter and probe with the positive lead.
>>>
>>> Third I would next probe the top terminal and the bottom terminal of
>>> the isolator with the positive meter lead and see what voltages are
> there.
>>> These terminals are the engine and house battery readings. If they are
>>> very low then wiggle the leads a bit where there are connected and see
> if
>>> one
>>> of the the leads is not making a good connection. Once you are sure
> that
>>> you have a good reading from both of them we can decide what to do
> next. A
>>> fully charged battery should read between 12.6 and 12.8 volts. If it
>>> reads down in the 12.0 or so range that battery is almost fully
> discharged.
>>>
>>> Fourth If you can start the GMC then start it and read the voltage on
>>> the center terminal of the isolator. This is the output of the
> Alternator.
>>> It should read in the 14.7 volt range. If it is good, then read the
>>> upper and lower isolator terminals again with the engine still running.
>>> They
>>> should both be around 14.0 volts.
>>>
>>> So please fill in the following voltage readings and one of the other
>>> guys here help you from there.
>>>
>>> _____ Volts across the engine battery without the engine running
>>> _____ Volts at upper isolator terminal without the engine running
>>> _____ Volts at lower isolator terminal without the engine running
>>> _____ Volts at center isolator terminal without the engine running
>>>
>>> _____ Volts at upper isolator terminal with the engine running
>>> _____ Volts at lower isolator terminal with the engine running
>>> _____ Volts at center isolator terminal with the engine running
>>>
>>> With the above information someone here will tell what direction to head
>>> next.
>>>
>>> If no one helps call my cell phone (two one nine) 263 8 one seven 4.
>>>
>>> Ken B.
>>> --
>>> Ken Burton - N9KB
>>> 76 Palm Beach
>>> Hebron, Indiana
>>>
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>>
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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