Home » Public Forums » GMCnet » What size engine battery do you use? (long post with trip report included)
| What size engine battery do you use? [message #93597] |
Wed, 28 July 2010 07:37  |
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I currently have a 875 cranking Amp/700 cold cranking amp engine start batter that looks very small for the GMC. This is what came with the GMC so not sure if it is correct.
What happened was that my alternator (80 amp) always seemed to be barely keeping up when running most things. When the air compressor for the suspension would kick on the voltage level shown on the digipanel would drop into the warning level. It would be back in green when it stopped but even the turn signal indicators would make it drop into the warning level. Was never really a problem though always had enough juice to start the engine.
This past weekend we had the A/C on high for the entire trip and the voltage level was in the warning more then the green level. (BTW hanging a clear shower curtain behind the front seats really kept us very cool with just dash A/C best thing we ever did). Stopped for gas and battery was dead and couldn't start it. I thought it might be "hot engine start" issue but the battery cable are all pretty new and connections are good. Had to take the Tracker (toad) and jump the GMC and finally got it started. I didn't turn it off again until at the campground. Had a great time with Grandkids and had my son in-law pick me up an 100 amp alternator. Installed the new alternator and was ready to head home. GMC still needed a jump to get started even though the combiner showed combined and charging. I just figured it never got a full charge and off we went. I didn't turn the engine off for the trip home and the voltage level on the digipanel was up where it should be with everything running so the new alternator is a must have.
Got home and battery was still dead so I am sure I killed the battery and need a new one.
Sorry for the long post but it was a great trip and we had a blast.
Thanks
Bob & Terry Stockholm
Xenia, OH
1976 PB
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| Re: What size engine battery do you use? [message #93602 is a reply to message #93597] |
Wed, 28 July 2010 07:56  |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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I'm just using the book recommended size for a 75 GM Toronado for the starting battery. Just a common battery from Wal-Mart. I like to be able to have warranty service at any Wal-Mart. Having said that, I have not had one fail. Is the ground directly to the block? This should be a short run of large gauge cable. Any possibility that something else is draining the battery? Do you have the house battery, or a second battery that is on the combiner that the solenoid can pull into the circuit for additional battery power? This heat is also challenging for your battery.
You can put almost any size battery in the engine compartment, just be sure that you can clear the engine hatch. I'm using a Marine Deep Cycle as second battery up front, and it is an interesting task to install and remove this big of a battery.
I did install the Ragusa 3 battery tray on the passenger side. Holding two batteries and assorted stuff. You can also install a larger battery by going thru the passenger side wheel well. Remove the liner, and you have lots of room.
You might also consider installing a relay to turn on the air compressor with a larger gauge wire to carry the load. You may have a voltage drop with the gauge that GMC installed After all, it is a few years old.
Tom Phipps,
75 GMC Ex-Avion
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] What size engine battery do you use? [message #93604 is a reply to message #93597] |
Wed, 28 July 2010 08:08 |
pete lyons
Messages: 81
Registered: June 2010
Karma: 0
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Bob,
I just installed a 975cca/1200 ca that I got from SAMs club for $79.
Ive struggled with "hot starting problems" for years, repeatedly replaced cables and starters and never realized I probably just never had enough juice to get the thing to turn over.
This is an awesome battery for starting.
Long story short, I broke the solenoid trying to tighten the starter cable since my coach wouldn't start because it was hot. I had another starter that I had replaced years ago because it wouldn't turn over when it was "hot". The coach still needed a jump, but at least I could get home.
Battery showed a full charge, but a replaced anyway. Bought the highest amp battery I could find, and lo and behold the coach fires right up, using what I had previously thought was a bad starter!!!
Now, even when hot, she spins like a top.
Just my two cents worth.
Pete Lyons
New albany, Indiana
76 eleganza II
Sent from my iPhone
On Jul 28, 2010, at 8:37 AM, Bob Stockholm <rstockholm@woh.rr.com> wrote:
>
>
> I currently have a 875 cranking Amp/700 cold cranking amp engine start batter that looks very small for the GMC. This is what came with the GMC so not sure if it is correct.
>
> What happened was that my alternator (80 amp) always seemed to be barely keeping up when running most things. When the air compressor for the suspension would kick on the voltage level shown on the digipanel would drop into the warning level. It would be back in green when it stopped but even the turn signal indicators would make it drop into the warning level. Was never really a problem though always had enough juice to start the engine.
>
> This past weekend we had the A/C on high for the entire trip and the voltage level was in the warning more then the green level. (BTW hanging a clear shower curtain behind the front seats really kept us very cool with just dash A/C best thing we ever did). Stopped for gas and battery was dead and couldn't start it. I thought it might be "hot engine start" issue but the battery cable are all pretty new and connections are good. Had to take the Tracker (toad) and jump the GMC and finally got it started. I didn't turn it off again until at the campground. Had a great time with Grandkids and had my son in-law pick me up an 100 amp alternator. Installed the new alternator and was ready to head home. GMC still needed a jump to get started even though the combiner showed combined and charging. I just figured it never got a full charge and off we went. I didn't turn the engine off for the trip home and the voltage level on the digipanel was up where it should be with everything run
ni
> ng so the new alternator is a must have.
>
> Got home and battery was still dead so I am sure I killed the battery and need a new one.
>
> Sorry for the long post but it was a great trip and we had a blast.
>
> Thanks
> --
> Bob & Terry Stockholm
> Xenia, OH
> 1976 PB
> _______________________________________________
> 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
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| Re: [GMCnet] What size engine battery do you use? [message #93609 is a reply to message #93604] |
Wed, 28 July 2010 08:35 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Starters draw a huge number of amps for a short period of time. When the
starter solenoid is engaged, on points type distributors there is a resistor
bypass circuit that is supposed to supply full voltage to the ignition coil.
This circuit has a separate lug on the starter and is only activated during
cranking. GM starter solenoids are notorious for having high resistance in
this circuit. What the driver would notice is that the engine seems to crank
OK but is hard to start, sometimes only catching just when you let up on the
ignition key from start to run. This circuit is tricky to diagnose because
you could have a bad starter solenoid, a failed primary resistor, a weak
battery, high resistance in the distributor due to points and or condensor
or conductors, a faulty ignition switch or some combination of the above
coupled with bad grounds between the engine and battery negative cables.
These coaches are all old and many of their wiring circuits have been messed
with by many different well intentioned owners and technicians. I know that
this is more confusing than helpful, but that is the nature of the problem.
If it were easy to troubleshoot and repair, it wouldn't be a problem. Kind
of a catch 22. First, check ALL battery cables that go between the battery,
isolator, and starter, as well as all ground straps from engine to frame and
chassis. If anything is loose or corroded, disconnect the ground strap from
the engine battery to prevent accidental arcing, then take off the suspect
wires one at a time, clean the corrosion to bright shiny metal. If in doubt,
replace them with same size or larger conductors, keeping them as short as
possible and still fit. On battery cables, I like to use a non-conductive
grease like petroleum jelly to coat the cables where they go to the battery.
Jim Hupy
Salem, Or
78 Royale 403
On Wed, Jul 28, 2010 at 6:08 AM, Pete <meandmygmcmh@gmail.com> wrote:
> Bob,
>
> I just installed a 975cca/1200 ca that I got from SAMs club for $79.
>
> Ive struggled with "hot starting problems" for years, repeatedly replaced
> cables and starters and never realized I probably just never had enough
> juice to get the thing to turn over.
>
> This is an awesome battery for starting.
> Long story short, I broke the solenoid trying to tighten the starter cable
> since my coach wouldn't start because it was hot. I had another starter that
> I had replaced years ago because it wouldn't turn over when it was "hot".
> The coach still needed a jump, but at least I could get home.
>
> Battery showed a full charge, but a replaced anyway. Bought the highest amp
> battery I could find, and lo and behold the coach fires right up, using what
> I had previously thought was a bad starter!!!
>
> Now, even when hot, she spins like a top.
> Just my two cents worth.
>
> Pete Lyons
> New albany, Indiana
> 76 eleganza II
>
> Sent from my iPhone
>
> On Jul 28, 2010, at 8:37 AM, Bob Stockholm <rstockholm@woh.rr.com> wrote:
>
> >
> >
> > I currently have a 875 cranking Amp/700 cold cranking amp engine start
> batter that looks very small for the GMC. This is what came with the GMC so
> not sure if it is correct.
> >
> > What happened was that my alternator (80 amp) always seemed to be barely
> keeping up when running most things. When the air compressor for the
> suspension would kick on the voltage level shown on the digipanel would drop
> into the warning level. It would be back in green when it stopped but even
> the turn signal indicators would make it drop into the warning level. Was
> never really a problem though always had enough juice to start the engine.
> >
> > This past weekend we had the A/C on high for the entire trip and the
> voltage level was in the warning more then the green level. (BTW hanging a
> clear shower curtain behind the front seats really kept us very cool with
> just dash A/C best thing we ever did). Stopped for gas and battery was dead
> and couldn't start it. I thought it might be "hot engine start" issue but
> the battery cable are all pretty new and connections are good. Had to take
> the Tracker (toad) and jump the GMC and finally got it started. I didn't
> turn it off again until at the campground. Had a great time with Grandkids
> and had my son in-law pick me up an 100 amp alternator. Installed the new
> alternator and was ready to head home. GMC still needed a jump to get
> started even though the combiner showed combined and charging. I just
> figured it never got a full charge and off we went. I didn't turn the engine
> off for the trip home and the voltage level on the digipanel was up where it
> should be with everything run
> ni
> > ng so the new alternator is a must have.
> >
> > Got home and battery was still dead so I am sure I killed the battery and
> need a new one.
> >
> > Sorry for the long post but it was a great trip and we had a blast.
> >
> > Thanks
> > --
> > Bob & Terry Stockholm
> > Xenia, OH
> > 1976 PB
> > _______________________________________________
> > 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
>
_______________________________________________
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List Information and Subscription Options:
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| Re: [GMCnet] What size engine battery do you use? [message #93640 is a reply to message #93622] |
Wed, 28 July 2010 11:06 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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| Dave Martin wrote on Wed, 28 July 2010 11:09 |
When I arrived at my destination a few days ago I parked then turned off the ignition. I decided to re-start to move ahead a few feet & discovered the entire dash was dead when I turned on the ignition key; no gauges, no lights, no buzzers, no starter, nothing.
The starting battery was completely dead. This was solved by jumping directly to it from the coach batteries. It appears that the alternator/starting battery diode in the isolator is fried, so the starting battery received no current while driving.
I think the boost solenoid is fried too.
I'm planning to replace both the isolator and boost relay with a big continuous duty solenoid activated by ignition switched power; that way boost will be on except when the ignition is off.
Dave(now in MN)
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Sir: This happened to me on a trip to NC. Isolater would not charge the coach batt. The boost sol is connected to the coach battery and would not activate. I jumped the sol which put the alt charging both systems and was able to go on with the trip with the (continous use HD sol) boost switch activated (not spring loaded). I replaced the isolater when I got home and all is well. I would not recommend wiring the boost sol to be activated at all times with the ignition. If you are going to do this, just wire it all together and throw the boost sol and isolater away. If I had the standard sol, or a spring loaded boost switch I could have put all 3 wires on the isolater on the same terminal. I would have still had to jump the sol to activate it off the house battery to start inatially till the coach battery came back to life.
Hope this isn`t to confusing.
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] What size engine battery do you use? [message #93657 is a reply to message #93656] |
Wed, 28 July 2010 11:49 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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I am sorry, I was referring to the link in my tag line
On Wed, Jul 28, 2010 at 9:46 AM, Mr.erf ERFisher <mr.erfisher@gmail.com>
read this link
http://gmcmotorhome.info/APC.html
there is a failure mode in alternators that will apply 100 volts to the
wires behind the dash. This cable will stop this from melting the wires .
> gene
>
>
>
>
> On Wed, Jul 28, 2010 at 9:40 AM, Dave Martin <dmartin@newarts.com> wrote:
>
>>
>>
>> Mr ERFisher wrote on Wed, 28 July 2010 11:14
>> > I hope you have an APC on just in case?
>>
>>
>> I'm not sure what you mean by an APC, but I've 5 deep cycle coach
>> batteries for back-up 12V power.
>>
>> Dave (@Ten Mile Lake, MN)
>> _______________________________________________
>> 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
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| Re: [GMCnet] What size engine battery do you use? [message #93660 is a reply to message #93650] |
Wed, 28 July 2010 12:09 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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[quote title=Dave Martin wrote on Wed, 28 July 2010 12:37][quote title=C Boyd wrote on Wed, 28 July 2010 11:06] I would not recommend wiring the boost sol to be activated at all times with the ignition. If you are going to do this, just wire it all together and throw the boost sol and isolater away....[/quote]
Why not?
If a solenoid switch activated by the ignition is placed between the chassis battery & alternator, the coach batteries cannot drain the chassis battery when the ignition is off and the alternator will charge the coach batteries when the engine is on.
The only downside I can envision is the solenoid might fail, if so, it can be jumped. Continuous duty solenoids are available for this kind of application.
At present I simply have them all wired together as you suggest.
Dave (now in MN)[/quote
Well Forests mom says stupid is what stupid does. I am famous for running it hard and putting it up wet. Like leaving the fridge on or a light on or the water pump on or something stupid like that. Meaning a few times my house battery has been dead but the engine battery hot. If I had the sol tied to ignition as you suggest with 5 dead deep cycle batteries drawing down the coach starting battery upon activation, I would think this would not be healthy for the starter motor??? Just my thoughts... I would rather have the engine start then let the isolater do its thing.
I also have the continous duty sol. This is why I wasn`t worried about flipping the boost switch and going on with the trip. Besides it was raining and I had already replaced the Alt before I figured out it was the isolater.... did I mention stupid?
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] What size engine battery do you use? [message #93661 is a reply to message #93650] |
Wed, 28 July 2010 12:14 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""Why not?
If a solenoid switch activated by the ignition is placed between the chassis battery & alternator, the coach batteries cannot drain the chassis battery when the ignition is off and the alternator will charge the coach batteries when the engine is on.
The only downside I can envision is the solenoid might fail, if so, it can be jumped. Continuous duty solenoids are available for this kind of application.
At present I simply have them all wired together as you suggest.
Dave (now in MN) ""
I threw away the isolator years ago and now use an inexpensive constant duty cycle solenoid that connects the house and chassis batteries with ignition on. The chassis battery is hooked directly to the alternator--no need for isolation there. The only thing that setup won't do is charge the chassis battery when my house batteries are being charged by the house converter, but I've never ever had the need to charge the chassis battery while sitting or camping.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: What size engine battery do you use? [message #93715 is a reply to message #93597] |
Wed, 28 July 2010 21:34 |
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I want to thank everyone for their answers and advice on what battery size to use like always they have helped me.
First thing I ever purchased and installed on the GMC was the APC so that part is covered.
I still have the old alternator that I will get checked out to see if it was also bad to help answer that question.
Battery was checked out today and it is dead so once I get the new one in I'll do more checking to see if there are any other issues.
Thanks again everyone.
Bob & Terry Stockholm
Xenia, OH
1976 PB
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| Re: [GMCnet] What size engine battery do you use? [message #93792 is a reply to message #93597] |
Thu, 29 July 2010 10:06 |
Richard Denney
Messages: 920
Registered: April 2010
Karma: 9
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Senior Member |
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On Wed, Jul 28, 2010 at 8:37 AM, Bob Stockholm <rstockholm@woh.rr.com>wrote:
>
> I currently have a 875 cranking Amp/700 cold cranking amp engine start
> batter that looks very small for the GMC. This is what came with the GMC so
> not sure if it is correct.
>
As I recall, the original battery was the standard Delco-style starting
battery with side terminals, and was not very large.
I've read all of the responses to your post, and some seem to feel the need
for a monster battery. What am I missing? My POB (Plain Old Battery) is
probably something in the factory-supplied range, and it spins the motor
like a top. If my engine spun slowly, I think I would suspect some other
issue.
The possibility that has the greatest ratio of likelihood-to-visibility is
the grounding. Check the ground strap from the engine block to the negative
battery terminal. I ran my negative battery cable to the engine block, and
then a strap from there to the frame. The starter won't get the current it
needs if the ground isn't tip-top, no matter how big the battery is. Most of
us just check the positive cable to the starter, and forget the ground.
Rick "well-grounded" Denney
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