| new alternator and starting battery still losing charge [message #234499] |
Mon, 30 December 2013 19:38  |
74CanyonLands
Messages: 81
Registered: September 2013
Location: Los Angeles
Karma: 0
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So I had a new heavy duty alternator put in and mind you the batteries were tired.
I kept losing charge and no problem used the battery from generator charged house battery to get going again. This eventually got tedious and not that faithful so I pulled over and put in a new starting battery. All went well for a while but the gen light was barely on the whole way home. Arrived home safe and sound but the battery was really weak when I tried a restart.
So I just wanted to post a pic of my setup and see if you gurus can ID the type of setup
I may have by looking at the pic. BTW It's a 74 canyons.
here is a link to pic
https://www.dropbox.com/s/3hu8kwboa0ho6u7/battery.jpg
There is a component I put a white square around can you id what that is?
Thanks gang,
CR
Curt Remington,
74 Canyonlands
Los Angeles, CA
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| Re: new alternator and starting battery still losing charge [message #234506 is a reply to message #234502] |
Mon, 30 December 2013 20:07  |
Otterwan
Messages: 946
Registered: July 2013
Location: Lynnwood (north of Seattl...
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It looks like your house and and start batteries share a single ground. I can't tell from the photo where the ground cable goes. A better configuration would be to have a separate ground cable from the house battery to the frame and a separate ground cable from the start battery to the engine block.
Have you checked the voltage a each battery with the engine running?
Is that the loose end of a shock absorber to the left of the front battery?
1977 Birchaven, Lynnwood WA - "We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."
[Updated on: Mon, 30 December 2013 20:08] Report message to a moderator |
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| Re: new alternator and starting battery still losing charge [message #234513 is a reply to message #234499] |
Mon, 30 December 2013 21:24 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Ok. Where do we start.
1. Check the ground cables. The engine battery negative cable goes the the engine block. The house battery goes to the aluminum frame of the coach (not the steel frame).
2. In the picture there is a yellow wire going to the engine battery. It is not OEM and I have no idea what it might be powering. You will have to follow it to find out. I see a Circuit Breaker in that line. It might be a PO added circuit for the suspension compressor or the heater fan.
3. Start the engine and go to the isolator (the finned thing not in the picture) with a voltmeter. Connect the negative side of the voltmeter to the aluminum plate that the isolator is mounted on. Now with the engine running probe the three connection bolts of the isolator. If the coach is still wired correctly, the top and bottom bolts are connected to the house and engine batteries. The center bolt is connected to the alternator. The center connection should read around 14.7 volts while the top and bottom bolts (connections) should read .7 volt less or around 14.0 volts.
4. If the voltage readings above are correct then move your volt meter across the two batteries one at a time. You are looking for the same 14.0 volts that you read at the isolator. If they are the same voltage, then you have a good engine alternator charging circuit to both batteries. You then probably have a weak battery or a discharge problem of the battery when the engine is not running.
That ought to get you started. Let us know what you are reading at the above points and we can go from there.
The thing in the picture inside the white drawn box is the battery boost solenoid (relay). It connects the two systems (house and engine) together when you move the boost switch on the dash.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
[Updated on: Wed, 01 January 2014 06:10] Report message to a moderator |
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| Re: new alternator and starting battery still losing charge [message #234525 is a reply to message #234499] |
Mon, 30 December 2013 23:04 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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All grounds should connect to 1 central point, like the engine block. This will stop ground loops, which have differences in potential (voltage) and can cause radio noise and electrical gremlins, anomalies, and electrolysis. The 2 battery grounds, the aluminum house frame, and the chassis frame should all be connected to the engine block, preferably at the same point, and with heavy (#4)cables.
I know this differs from what others have said, but this is what I learned in college and from experience, especially when installing communication equipment. It can be looked up in textbooks and probably online too, just Google "ground loop"
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] new alternator and starting battery still losing charge [message #234527 is a reply to message #234525] |
Mon, 30 December 2013 23:34 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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in fact, after 35 years of lab automation
I feel the GMC is a ground grid,
with the engine as "mother earth"
google ,ground grid
jwid
gene
On Mon, Dec 30, 2013 at 9:04 PM, Terry <mrbullitt@verizon.net> wrote:
>
>
> All grounds should connect to 1 central point, like the engine block. This
> will stop ground loops, which have differences in potential (voltage) and
> can cause radio noise and electrical gremlins, anomalies, and electrolysis.
> The 2 battery grounds, the aluminum house frame, and the chassis frame
> should all be connected to the engine block, preferably at the same point,
> and with heavy (#4)cables.
>
> I know this differs from what others have said, but this is what I learned
> in college and from experience, especially when installing communication
> equipment. It can be looked up in textbooks and probably online too, just
> Google "ground loop"
> --
> Terry Kelpien
> 73 Glacier 260
> Smithfield, Va.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List 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
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| Re: new alternator and starting battery still losing charge [message #234528 is a reply to message #234525] |
Mon, 30 December 2013 23:42 |
Phantom2
Messages: 94
Registered: September 2012
Location: Springfield, IL
Karma: 0
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Does the battery go dead while driving or when it sets?
I had a 66 Cadillac Deville convertible that the battery would lose its charge between drives. I found the kick-down switch on the carb that told the transmission to downshift was stuck closed.
Remove the positive cable from the battery & touch the batt terminal with the cable repeatedly & if it sparks or you hear a click or whirr something is on.
Larry
Larry Hopkins
75 Avion
Springfield, IL
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| Re: new alternator and starting battery still losing charge [message #234539 is a reply to message #234535] |
Tue, 31 December 2013 03:04 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| 74CanyonLands wrote on Tue, 31 December 2013 00:46 |
You guys are the best, thank you again.
Also Ken I have never read so much info refined into such a
small concise post.
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That is unusual. Usually I get too wordy and put in too much information. I answer this same question one every 2 or 3 months here, so tonight I started on a 12 volt GMC trouble shooting flow chart tonight.
People get a little confused on a GMC because there are two separate 12 volt systems in a GMC with two master grounds. When working on anything electrical you need to think about which system is powering (and grounding) it. After a while they get them inner connected and cause problems.
Let's see how far you get with the posted information and we will take it from there. GM knew what they were doing when they designed the systems. It is PO and current owners modifying things that cause problems and make things difficult to diagnose.
The only strange thing in GM's design was the ground path for the dash and the aluminum front plate. It works OK as designed (no ground loops) but it was a strange way to go about it.
Let us know what you find.
If you want the initial start I did tonight on this flow chart, PM me your email address and I'll send you the first page. It is not in finished form. I haven't even spell checked it yet and I mis-type thing all the time.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: new alternator and starting battery still losing charge [message #234595 is a reply to message #234499] |
Tue, 31 December 2013 14:20 |
74CanyonLands
Messages: 81
Registered: September 2013
Location: Los Angeles
Karma: 0
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So here is the poop.
New Battery before starting:
10.57v
top post of isolator with engine running:
11.79v
center post:
216 mv
bottom post:
10.27v
is there another way to check alternator because it's brand new...
Also can I do similar voltage tests to the boost solenoid?
Thanks guys looks like I will be able to track this down eventually thanks to you.
CR
Curt Remington,
74 Canyonlands
Los Angeles, CA
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| Re: new alternator and starting battery still losing charge [message #234596 is a reply to message #234595] |
Tue, 31 December 2013 15:06 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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If that is the resting voltage of that battery before testing, it has a dead cell. Resting means it has been charged with a battery charger and then left to sit for about 10 minutes with nothing connected to it. It should read about 12.6 at rest.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: new alternator and starting battery still losing charge [message #234598 is a reply to message #234595] |
Tue, 31 December 2013 15:12 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Each cell of a lead-acid battery is responsible for 2.1 volts, they add in series to make 12.6. A dead cell will overwork the alternator and is probably why your GEN light was glowing. Too much load trying to make up for that dead cell. Charge it for 30 minutes, put a headlight or some significant load on it for 15 seconds to drain the surface charge, and then check the voltage. You can check the specific gravity of each cell with a hygrometer, but if it's new, just take it back right away and get it replaced.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
[Updated on: Tue, 31 December 2013 15:35] Report message to a moderator |
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