| dead sob battery [message #118116] |
Tue, 08 March 2011 20:41  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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My neighbor has a 2007 Bounder that has a drain on the starting battery. He recently replaced what he thought was a bad battery with a new 1000 cca battery.After sitting less then a month it was stone dead. I checked it and found it has a 300Ma phantom drain on this starting battery.On our GMC's we should have almost no phantom loads (maybe 10 Ma)Is this normal for newer motor homes with all the electronics they have? I can't imagine trying to trace out that bugger with no wiring diagrams ! I told him to leave it plugged in or unhook the battery. Stuff like this makes me like my GMC all the more.
Roy
76 x glen brook
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: dead sob battery [message #118131 is a reply to message #118122] |
Tue, 08 March 2011 21:28  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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That was the first thing I checked ,the solar battery is OK its the constant 300Ma drain I wounder about. the solar panel will do zip at night. The only loads I would think would be the engine computer and the dash radio ? But should they draw
that much current with every thing off?
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: dead sob battery [message #118151 is a reply to message #118116] |
Tue, 08 March 2011 22:58 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Use the same approach that you would do on a GMC. Disconnect one battery cable and run it through an ammeter that can be adjusted down to lower (ma.) scales. Read the load and start pulling fuses until you find which load the fuse is on.
If it is a modern engine with a Body and Engine computer, then the computer load is there all time. The BCM usually goes to sleep after a short period of time of inactivity and the load drops to 15 ma or so. If something is keeping the BCM awake then it's load will be in the 300 ma range. First determine if the BCM is the load culprit by pulling fuses before trying to find out what is keeping it awake.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] dead sob battery [message #118153 is a reply to message #118131] |
Tue, 08 March 2011 23:30 |
Douglas Norton
Messages: 191
Registered: April 2008
Karma: 0
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Other electronic draws can include a minute draw from a fantastic fan if it is wireless, a solar panel without a diode to prevent back feed, bad corosion between a positive connection and ground, and the refrigerator if it is electronic. Consider pulling fuses and measuring amperage across the fuse slots to
see if it can be partially isolated that way. There is a reason they
are called phantom loads.
I had a phantom draw in my GMC that was varied from 200 to over 500 ma. It got worse in the rainy season. Seems the wire from the rear house bateries to the front isolator was in a channel that was filled with water. Perhaps a mouse chewed on it or it had a small crack or pinhole in the insulation. The more it leaked dc, the more concentrated the remaining salty water became. Finally I found it was making a sizzling noise and I put the cell phone back there and my wife told me where it was loudest.
Doug Norton
--- On Tue, 3/8/11, roy keen <roynpaula@charter.net> wrote:
From: roy keen <roynpaula@charter.net>
Subject: Re: [GMCnet] dead sob battery
To: gmclist@temp.gmcnet.org
Date: Tuesday, March 8, 2011, 7:28 PM
That was the first thing I checked ,the solar battery is OK its the constant 300Ma drain I wounder about. the solar panel will do zip at night. The only loads I would think would be the engine computer and the dash radio ? But should they draw
that much current with every thing off?
Roy
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| Re: dead sob battery [message #118192 is a reply to message #118151] |
Wed, 09 March 2011 11:16 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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[If it is a modern engine with a Body and Engine computer, then the computer load is there all time. The BCM usually goes to sleep after a short period of time of inactivity and the load drops to 15 ma or so. If something is keeping the BCM awake then it's load will be in the 300 ma range. First determine if the BCM is the load culprit by pulling fuses before trying to find out what is keeping it awake. [/quote]
That sounds like the most logical explanition. I found 2 wall switches inside the coach one said house battery the other said engine battery. turning them too off showed a 15 Ma constant drain. The solar panel is only about 4"by 8" so I doubt if it could do much against a 300 Ma constant drain. There are no electrical schematics with the coach and most likely hard to obtain. I didn't want to get too involved with no schematics I just needed to know if 300 Ma was normal for a newer unit.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: dead sob battery [message #118241 is a reply to message #118192] |
Wed, 09 March 2011 20:08 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| roy1 wrote on Wed, 09 March 2011 11:16 |
[If it is a modern engine with a Body and Engine computer, then the computer load is there all time. The BCM usually goes to sleep after a short period of time of inactivity and the load drops to 15 ma or so. If something is keeping the BCM awake then it's load will be in the 300 ma range. First determine if the BCM is the load culprit by pulling fuses before trying to find out what is keeping it awake.
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That sounds like the most logical explanation. I found 2 wall switches inside the coach one said house battery the other said engine battery. turning them too off showed a 15 Ma constant drain. The solar panel is only about 4"by 8" so I doubt if it could do much against a 300 Ma constant drain. There are no electrical schematics with the coach and most likely hard to obtain. I didn't want to get too involved with no schematics I just needed to know if 300 Ma was normal for a newer unit.
Roy[/quote]
I was chasing a similar problem on my Colorado a year or two ago. I found documentation somewhere that said GM wanted the static drain below to be 20 ma. I finally found that an aftermarket temperature / compass mirror that I added was keeping the BCM awake. I changed the power source for the mirror to a circuit that the BCM was not watching. Now my static drain is 18ma including the mirror. Even at that rate GM says the battery could go dead after 1 month without starting it or charging the battery.
If he is going to park that for long periods of time, I suggest a battery disconnect switch.
I suggest a battery disconnect switch for other reasons also. I had a fire where the fuel pump stuck on feeding the fire in my coach. The quick disconnect is the only thing that kept the coach from burning to the ground. Even with that pump failure I still had $10,000 damage and 3 months work to get the coach back running again. That fire sure ruined my summer. I have disconnect switches on both my house and engine batteries.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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