Home » Public Forums » GMCnet » Engine battery monitor
| Engine battery monitor [message #75978] |
Mon, 08 March 2010 10:26  |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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Senior Member |
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My coach has a history of electrical system failures, including 3 alternators and 2 batteries in the 3 years prior to my getting the coach. I didn't get a clear answer from the PO as to any firm conclusions explaining the repeated problems, other than speculating about just bad luck to get two, bad rebuilt alternators in a row.
In any case, I've been wondering how to monitor the sitution, and coincidentally I'm in the process of installing a Xantrex battery monitor for the house batteries, intending this summer to install some solar panels, and am wondering about installing a shunt to monitor the engine battery.
I know Xantrex has a 500a shunt available, and I'm thinking I could just hook one in either the engine battery negative line or the positive, in either case making sure that all power in or out of the battery went through the shunt, then hook up a digital panel meter to read the drop across the shunt. Of course I don't need the computer calculations that Xantrex provides to keep track of house battery capacity, I just need to see the current charging or discharging the battery, and it seems to me that just reading the voltage across the shunt, with some suitable calibration conversion, would do that for me.
Thoughts?
J Rabe
76 Palm Beach
Portland, OR
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| Re: Engine battery monitor [message #75981 is a reply to message #75978] |
Mon, 08 March 2010 10:43  |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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Senior Member |
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| jayrabe wrote on Mon, 08 March 2010 08:26 |
My coach has a history of electrical system failures, including 3 alternators and 2 batteries in the 3 years prior to my getting the coach. I didn't get a clear answer from the PO as to any firm conclusions explaining the repeated problems, other than speculating about just bad luck to get two, bad rebuilt alternators in a row.
In any case, I've been wondering how to monitor the sitution, and coincidentally I'm in the process of installing a Xantrex battery monitor for the house batteries, intending this summer to install some solar panels, and am wondering about installing a shunt to monitor the engine battery.
I know Xantrex has a 500a shunt available, and I'm thinking I could just hook one in either the engine battery negative line or the positive, in either case making sure that all power in or out of the battery went through the shunt, then hook up a digital panel meter to read the drop across the shunt. Of course I don't need the computer calculations that Xantrex provides to keep track of house battery capacity, I just need to see the current charging or discharging the battery, and it seems to me that just reading the voltage across the shunt, with some suitable calibration conversion, would do that for me.
Thoughts?
J Rabe
76 Palm Beach
Portland, OR
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You can do what you mentioned, use a shunt on the battery circuit to allow you to have effectively an ammeter in the engine battery circuit. I would not run the starter current through it as it can easily overload the shunt. Very small currents may not be easy to read on a shunt as large as 500 amps.
I am not sure what you want to do with this information. Do you think the battery has some small discharge causing it to go dead? If so, a careful one time check of discharge current with a smaller ammeter would probably reveal the problem and removal of one fuse at a time will generally isolate where it is occurring. If you think the alternator is not working, a simple voltage check will be just as effective, when the engine is running, the voltage at the battery should be in the 13.8 to 14.2 range.
There is nothing wrong with a real ammeter in the circuit, cars up until the mid 50's had them as standard equipment. But I am not sure this will really identify what your electrical issues are in your coach.
I am sure others will chime in here.
Rob Allen
former owner of '76 x-PB
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| Re: Engine battery monitor [message #75985 is a reply to message #75978] |
Mon, 08 March 2010 11:23 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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First of all of those failures in such a short period of time make me wonder if all of those items were really bad.
What are you wanting to monitor? Years ago cars had an ammeter between the battery everything except the starter. They showed rates of charge and discharge. With those high amperage meters it was impossible to see the state of charge or slow parasitic drains.
Then we went to the idiot (red) light that only showed that the generator / alternator was charging or not. Today most cars have voltmeters. The voltmeter shows the current state of charge and the current voltage output from the alternator. If you want to see the current state of charge (voltage), there are several plug-in devices that go in the cigarette light plug that will give you that. Harbor Freight has one that has different color leds. There is one sitting on my Blazer dash right now. Walmart has one that has LEDs and a voltmeter. I have one of these in the glove box of my GMC. The Walmart one is around $15.00.
If you are looking for parasitic drains then you will need a ammeter that reads in the mili-amp ranges. If I I were using one of these I would only install it while testing and immediately remove it before using the coach. Almost all Digital VOMs have an ammeter function with several scales of 10 amps and less.
I'm not sure what you want to measure.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Engine battery monitor [message #76003 is a reply to message #75978] |
Mon, 08 March 2010 15:31 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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I am somewhat familiar with your coach, (as you know). I tried to work on
the coach for the PO but by that time, he had lost confidence in the GMC and
had it up for sale. I know the PO did none of his own work, and had no
idea what was done to his coach, other than he had problems.
It is not unusual to get several bad rebuilt alternators from part houses
since they never replace the stator windings and most of the 30 year old
alternators need all the mechanical, electrical, and stator windings
replaced.
Here are my recommendations. (click on the links)
*
VOLTMETER*
You can learn everything you need to know about the alternator and battery
condition with a volt meter. (center terminal of diode isolator should be
14.7 with engine running)
Buy a low cost 3-1/2 digit digital voltmeter (harbor freight for less than
$10) . I like the Radio Shack one, because it will turn it's self off when
you forget to turn it off.
http://users.sfo.com/~eagle/instr.html#digital
*APC CABLE*
Install an APC cable so your alternator light does not glow dim and a bad
alternator will not burn up the wires behind the dash.
http://gmcmotorhome.info/APC.html
*COMBINER*
Install a combiner across the diode isolator. This will charge all
batteries from all sources and will compensate for several problems the
diode isolator may have.
*http://tinyurl.com/ye5jato*
*BATTERY CONDITION*
A charged battery at rest should be about 12.5 volts
A battery at rest at 12 volts, is 1/2 discharged
A smart charger should be holding your charge rate at 13.6 volts.
*http://tinyurl.com/yl83xs6*
and finally, wait until middle June, and come back to Florence, Orgn (when I
am back there)and we will work on your GMC together;>)
gene
My coach has a history of electrical system failures, including 3
> alternators and 2 batteries in the 3 years prior to my getting the coach. I
> didn't get a clear answer from the PO as to any firm conclusions explaining
> the repeated problems, other than speculating about just bad luck to get
> two, bad rebuilt alternators in a row.
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Engine battery monitor [message #76004 is a reply to message #76003] |
Mon, 08 March 2010 15:46 |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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Senior Member |
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Gene,
Seems the last 2 links in your post are not working.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Here are my recommendations. (click on the links)
*
VOLTMETER*
You can learn everything you need to know about the alternator and battery
condition with a volt meter. (center terminal of diode isolator should be
14.7 with engine running)
Buy a low cost 3-1/2 digit digital voltmeter (harbor freight for less than
$10) . I like the Radio Shack one, because it will turn it's self off when
you forget to turn it off.
http://users.sfo.com/~eagle/instr.html#digital
*APC CABLE*
Install an APC cable so your alternator light does not glow dim and a bad
alternator will not burn up the wires behind the dash.
http://gmcmotorhome.info/APC.html
*COMBINER*
Install a combiner across the diode isolator. This will charge all
batteries from all sources and will compensate for several problems the
diode isolator may have.
*http://tinyurl.com/ye5jato*
*BATTERY CONDITION*
A charged battery at rest should be about 12.5 volts
A battery at rest at 12 volts, is 1/2 discharged
A smart charger should be holding your charge rate at 13.6 volts.
*http://tinyurl.com/yl83xs6*
and finally, wait until middle June, and come back to Florence, Orgn (when I
am back there)and we will work on your GMC together;>)
gene
Bukzin
1977 Palm Beach
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| Re: [GMCnet] Engine battery monitor [message #76007 is a reply to message #76003] |
Mon, 08 March 2010 15:52 |
zhagrieb
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
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Senior Member |
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I'd look very carefully for bad connections; whether loose, frayed, or
corroded. Bad connections cause high resistance which raises hell with
voltage and current flow. This, in turn, can cause premature component
failure.
Glenn Giere
On Mon, Mar 8, 2010 at 1:31 PM, Mr.erf ERFisher <mr.erfisher@gmail.com>wrote:
> I am somewhat familiar with your coach, (as you know). I tried to work on
> the coach for the PO but by that time, he had lost confidence in the GMC
> and
> had it up for sale. I know the PO did none of his own work, and had no
> idea what was done to his coach, other than he had problems.
>
> It is not unusual to get several bad rebuilt alternators from part houses
> since they never replace the stator windings and most of the 30 year old
> alternators need all the mechanical, electrical, and stator windings
> replaced.
>
> Here are my recommendations. (click on the links)
> *
> VOLTMETER*
> You can learn everything you need to know about the alternator and battery
> condition with a volt meter. (center terminal of diode isolator should be
> 14.7 with engine running)
> Buy a low cost 3-1/2 digit digital voltmeter (harbor freight for less than
> $10) . I like the Radio Shack one, because it will turn it's self off when
> you forget to turn it off.
> http://users.sfo.com/~eagle/instr.html#digital<http://users.sfo.com/%7Eeagle/instr.html#digital>
>
> *APC CABLE*
> Install an APC cable so your alternator light does not glow dim and a bad
> alternator will not burn up the wires behind the dash.
> http://gmcmotorhome.info/APC.html
>
> *COMBINER*
> Install a combiner across the diode isolator. This will charge all
> batteries from all sources and will compensate for several problems the
> diode isolator may have.
> *http://tinyurl.com/ye5jato*
>
> *BATTERY CONDITION*
> A charged battery at rest should be about 12.5 volts
> A battery at rest at 12 volts, is 1/2 discharged
> A smart charger should be holding your charge rate at 13.6 volts.
> *http://tinyurl.com/yl83xs6*
>
> and finally, wait until middle June, and come back to Florence, Orgn (when
> I
> am back there)and we will work on your GMC together;>)
>
> gene
>
>
>
>
>
>
> My coach has a history of electrical system failures, including 3
> > alternators and 2 batteries in the 3 years prior to my getting the coach.
> I
> > didn't get a clear answer from the PO as to any firm conclusions
> explaining
> > the repeated problems, other than speculating about just bad luck to get
> > two, bad rebuilt alternators in a row.
> >
>
>
>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Glenn Giere, Portland OR, K7GAG
'73 "Moby the Motorhome" 26'
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| Re: [GMCnet] Engine battery monitor [message #76015 is a reply to message #76004] |
Mon, 08 March 2010 17:13 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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I tested them all on gmail, (three times now) and they all work
gene
On Mon, Mar 8, 2010 at 1:46 PM, Richard <bukzin@gmail.com> wrote:
>
>
>
>
> Gene,
>
> Seems the last 2 links in your post are not working.
>
>
>
>
>
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
>
>
> Here are my recommendations. (click on the links)
> *
> VOLTMETER*
> You can learn everything you need to know about the alternator and battery
> condition with a volt meter. (center terminal of diode isolator should be
> 14.7 with engine running)
> Buy a low cost 3-1/2 digit digital voltmeter (harbor freight for less than
> $10) . I like the Radio Shack one, because it will turn it's self off when
> you forget to turn it off.
> http://users.sfo.com/~eagle/instr.html#digital<http://users.sfo.com/%7Eeagle/instr.html#digital>
>
> *APC CABLE*
> Install an APC cable so your alternator light does not glow dim and a bad
> alternator will not burn up the wires behind the dash.
> http://gmcmotorhome.info/APC.html
>
> *COMBINER*
> Install a combiner across the diode isolator. This will charge all
> batteries from all sources and will compensate for several problems the
> diode isolator may have.
> *http://tinyurl.com/ye5jato*
>
> *BATTERY CONDITION*
> A charged battery at rest should be about 12.5 volts
> A battery at rest at 12 volts, is 1/2 discharged
> A smart charger should be holding your charge rate at 13.6 volts.
> *http://tinyurl.com/yl83xs6*
>
> and finally, wait until middle June, and come back to Florence, Orgn (when
> I
> am back there)and we will work on your GMC together;>)
>
> gene
>
>
>
>
> --
> Bukzin
> 1977 Palm Beach
> Chico California
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
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| Re: [GMCnet] Engine battery monitor [message #76017 is a reply to message #76015] |
Mon, 08 March 2010 17:16 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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well take that back, just did a reload and now they don't work, I will go
fix
thanks
gene
On Mon, Mar 8, 2010 at 3:13 PM, Mr.erf ERFisher <mr.erfisher@gmail.com>wrote:
> I tested them all on gmail, (three times now) and they all work
>
>
> gene
>
>
>
>
>
> On Mon, Mar 8, 2010 at 1:46 PM, Richard <bukzin@gmail.com> wrote:
>
>>
>>
>>
>>
>> Gene,
>>
>> Seems the last 2 links in your post are not working.
>>
>>
>>
>>
>>
>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>
>>
>>
>> Here are my recommendations. (click on the links)
>> *
>> VOLTMETER*
>> You can learn everything you need to know about the alternator and battery
>> condition with a volt meter. (center terminal of diode isolator should be
>> 14.7 with engine running)
>> Buy a low cost 3-1/2 digit digital voltmeter (harbor freight for less
>> than
>> $10) . I like the Radio Shack one, because it will turn it's self off
>> when
>> you forget to turn it off.
>> http://users.sfo.com/~eagle/instr.html#digital<http://users.sfo.com/%7Eeagle/instr.html#digital>
>>
>> *APC CABLE*
>> Install an APC cable so your alternator light does not glow dim and a bad
>> alternator will not burn up the wires behind the dash.
>> http://gmcmotorhome.info/APC.html
>>
>> *COMBINER*
>> Install a combiner across the diode isolator. This will charge all
>> batteries from all sources and will compensate for several problems the
>> diode isolator may have.
>> *http://tinyurl.com/ye5jato*
>>
>> *BATTERY CONDITION*
>> A charged battery at rest should be about 12.5 volts
>> A battery at rest at 12 volts, is 1/2 discharged
>> A smart charger should be holding your charge rate at 13.6 volts.
>> *http://tinyurl.com/yl83xs6*
>>
>> and finally, wait until middle June, and come back to Florence, Orgn (when
>> I
>> am back there)and we will work on your GMC together;>)
>>
>> gene
>>
>>
>>
>>
>> --
>> Bukzin
>> 1977 Palm Beach
>> Chico California
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
>
> --
> Gene Fisher -- 74-23,77PB/ore/ca
> “Give a man a fish; you have fed him for today --- give him a URL and
> -------
> http://gmcmotorhome.info/
> Alternator Protection Cable
> http://gmcmotorhome.info/APC.html
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
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| [GMCnet] Fwd: Engine battery monitor [message #76018 is a reply to message #76003] |
Mon, 08 March 2010 17:19 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
|
Senior Member |
|
|
problem with tinyurl
here it is with original links
gene
I am somewhat familiar with your coach, (as you know). I tried to work on
the coach for the PO but by that time, he had lost confidence in the GMC and
had it up for sale. I know the PO did none of his own work, and had no
idea what was done to his coach, other than he had problems.
It is not unusual to get several bad rebuilt alternators from part houses
since they never replace the stator windings and most of the 30 year old
alternators need all the mechanical, electrical, and stator windings
replaced.
Here are my recommendations. (click on the links)
*
VOLTMETER*
You can learn everything you need to know about the alternator and battery
condition with a volt meter. (center terminal of diode isolator should be
14.7 with engine running)
Buy a low cost 3-1/2 digit digital voltmeter (harbor freight for less than
$10) . I like the Radio Shack one, because it will turn it's self off when
you forget to turn it off.
http://users.sfo.com/~eagle/instr.html#digital<http://users.sfo.com/%7Eeagle/instr.html#digital>
*APC CABLE*
Install an APC cable so your alternator light does not glow dim and a bad
alternator will not burn up the wires behind the dash.
http://gmcmotorhome.info/APC.html
*COMBINER*
Install a combiner across the diode isolator. This will charge all
batteries from all sources and will compensate for several problems the
diode isolator may have.
*
http://www.gmcmhphotos.com/photos/showphoto.php?photo=24994&title=adding-a-combiner-to-a&cat=4944<http://tinyurl.com/ye5jato>
*
*BATTERY CONDITION*
A charged battery at rest should be about 12.5 volts
A battery at rest at 12 volts, is 1/2 discharged
A smart charger should be holding your charge rate at 13.6 volts.
*http://www.gmcmhphotos.com/photos/showphoto.php?photo=17533&cat=4507<http://tinyurl.com/yl83xs6>
*
and finally, wait until middle June, and come back to Florence, Orgn (when I
am back there)and we will work on your GMC together;>)
gene
My coach has a history of electrical system failures, including 3
> alternators and 2 batteries in the 3 years prior to my getting the coach. I
> didn't get a clear answer from the PO as to any firm conclusions explaining
> the repeated problems, other than speculating about just bad luck to get
> two, bad rebuilt alternators in a row.
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
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| Re: Engine battery monitor [message #76065 is a reply to message #75995] |
Tue, 09 March 2010 06:21 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
|
Senior Member |
|
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| WD0AFQ wrote on Mon, 08 March 2010 13:24 |
Dang, was hoping you would come help me at Jim's table. You can not be as broke as Teri and I are. Gas is cheap. We can pitch a tent under our awning.
Dan
|
That's OK Dan. I already made the decision. It is strictly an economic one. I would love to be there. I'll be at Eastern States in Calhoun, Ga. and Bean Station the following week. I think Jim Miller will probably be hosting Hamilton again this year and it will probably be the week after Bean Station or the week after Dayton. I hope you can make one or more of these.
I'm still wanting to see the picture of Frank Jenkins handing Jim his $100. Also if you can, get a picture of JimK's tow truck towed.
How about putting a tow truck towed behind JimK's pinewood derby GMC.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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