| [GMCnet] Parasitic draw from somewhere [message #301473] |
Thu, 02 June 2016 21:43  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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We have not experienced any issues of any kind with electrical stuff until this morning. after two nights dry camping we had a dead AGM chassis battery. There was not enough available amperage to start with just the boost switch and a dead chassis battery. The house bank is 460 amp hours so easily started the generator. The combiner looked like it worked properly, was disconnected before starting the generator and connected as soon as it sensed the charge current. After a few minutes of throwing charge into the chassis battery it would start using the boost switch. Once started the alternator provided charge for both the chassis and house banks. A few miles of driving and the chassis battery easily started the engine again.
The issue is, where is a big enough parasitic draw to discharge the chassis battery in just two days? I checked the electric choke (seems to work properly - no draw with key off and the expected 12+ vdc with the key on), and the AC clutch and both appear to be fine. No lights left on, key not left on, fan off. So far I am stumped and certainly open to suggestions!
Jerry, now in Soldotan, AK.
Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Parasitic draw from somewhere [message #301476 is a reply to message #301473] |
Thu, 02 June 2016 22:27  |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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I'll usually just hook up an ammeter in series with the negative lead and see what kind of current is being pulled. If it's high, I'll just start pulling fuses until the high drain drops back down, then troubleshoot from there. Of course, no need to pull fuses that aren't hot with the key off. On my coach, the stereo draws a little power all the time, though not nearly enough to drain a healthy battery in a couple days.
Good luck with the search!
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] Parasitic draw from somewhere [message #301482 is a reply to message #301473] |
Fri, 03 June 2016 00:04 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Bad alternator diodes will drain a good battery in less than 24 hrs and make a warm alternator when the engine is cold. The alternator will also whine and there may be noise in the radio.
Some aftermarket ignition systems are powered all the time.
Anything draining a charged battery in 48 hrs is generating some heat or some noise or both.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] Parasitic draw from somewhere [message #301490 is a reply to message #301476] |
Fri, 03 June 2016 03:35 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Just as a reference, I got involved with a parasitic draw problem on my Colorado a few years back. I found that the design standard from GM was that a vehicle must draw less than 20 ma. (.020 amps) after the computers went to sleep. I had around 350 ma. draw and in two days the battery was low enough that it would not start. So if you are chasing a parasitic draw problem with a meter look for less than 20 ma. My Colorado now draws 18 ma.
One other thought is batteries can internally short and draw themselves down over time. So do not rule out a battery as a possibility. An easy way to prove it is not the battery is to disconnect the battery for a few days and see if it still goes down.
You don't have two batteries wired in parallel do you?
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Parasitic draw from somewhere [message #301494 is a reply to message #301473] |
Fri, 03 June 2016 08:25 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I don't think the bad alt diodes applies here as the isolator will prevent flow back to the alt. Like Ken said, don't rule out the battery itself for the reasons he explained. Also under this assumption, wear safety glasses when troubleshooting. If the battery is the problem, it is more likely to explode when those symptoms are listed.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Parasitic draw from somewhere [message #301497 is a reply to message #301494] |
Fri, 03 June 2016 08:52 |
Ray Erspamer
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
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I just went through this for a friend. I hooked up a 12v DC light bulb between the negative battery terminal and wire. Pulled every fuse and it stayed on. Tired out the under hood light had an internal short. Disconnected it and the light went out.
Ray Erspamer
78 GMC Royale Center Kitchen
403, 3.70 Final Drive
Holley Sniper Quadrajet EFI System,
Holley Hyperspark Ignition System
414-484-9431
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| Re: [GMCnet] Parasitic draw from somewhere [message #301505 is a reply to message #301497] |
Fri, 03 June 2016 09:38 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Jerry, rough roads play havoc with electrical connections. I would start
with the battery cables and connectors at your inverter and converter. A
loose or corroded connection can cause the problems you are having. Check
the obvious stuff first. What I would do.
Jim Hupy
Salem, Or (presently at a GMC gathering in Maple Valley, near Tacoma, Wa)
On Jun 3, 2016 6:53 AM, "Ray Erspamer" wrote:
> I just went through this for a friend. I hooked up a 12v DC light bulb
> between the negative battery terminal and wire. Pulled every fuse and it
> stayed on. Tired out the under hood light had an internal short.
> Disconnected it and the light went out.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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