Parasitic draw question [Archive]

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RobertGary1

07-09-2009, 01:44 PM

Vehicle: 06 Vue V6 all factory (no aftermarket accessories), original factory battery

Complaint: If vehicle sits for about 8 hours battery is too weak to start, otherwise starts normally.

Visual: Looked over the battery connection and other than a slight amount of chalking didn't see anything bad. Noted as interesting a small amount of "dampness" around both terminal posts though. Not sure why.

Testing: Charged battery and conducted a load test. Battery measured good at 500 amps load. Tested alternator, voltage and load test passed.
Conducted a Parasitic load test with an inline Cen-tech meter. Found parasitic draw to be about 70 mA after the interior lights went out. Isolated to the "BCM/CLUSTR" circuit. However, load went away after 15 minutes. Additional tests showed the same, after 15 min the load went down to around 15mA. (15mA should give 45 days of charge according to the book).

Now, I know that 70mA is not enough to worry about (chart shows battery should hold good for 8 days at 70 mA), but the BCN is not listed as a delayed draw device in my paperwork (only the interior lights and CD changer). A quick look at the schematics seems to indicate that this circuit is used for the factory alarm and some part of the SRS. Anyone care to guess what this draw could be from (i.e why would it draw for 15 minutes). BTW: car was unlocked so I assume the alarm wasn't active.

In anycase, this isn't related to the vehicles problem. I'm recharging the battery now and will disconnect it from the vehicle and let it sit for 8 hours to see if it holds charge isolated. Maybe there is some sort of internal resistence in the battery; but I've not see that before. Otherwise, some gremlin is coming on in the middle of the night increasing the 15 mA sustained draw I'm seeing. Unfortunately my gauge doesn't have a logger so I can't review 8 hours of history unless I stand and look at it for 8 hours. To draw the battery in 8 hours should require about 800mA according to my book.

-Robert

3RedLines

07-09-2009, 02:08 PM

Anyone care to guess what this draw could be from (i.e why would it draw for 15 minutes). BTW: car was unlocked so I assume the alarm wasn't active.
-Robert

I can't say for sure about the 06, but in earlier models the EVAP system is monitored for awhile after a drive cycle.

(quote from service manual)
The engine off natural vacuum, (EONV), diagnostic is the small leak detection diagnostic for the evaporative emission (EVAP) system. The EONV diagnostic monitors the EVAP system pressure or vacuum with the key OFF. The EONV utilizes the temperature changes and the resulting naturally occurring vacuum or pressure in the fuel tank immediately following a drive cycle. When the vehicle is driven, the temperature in the fuel tank rises. When the vehicle is parked with the engine OFF and key OFF, the temperature in the fuel tank will continue to rise for a period of time, and then begin to decrease. The EONV diagnostic relies on this temperature change, and the corresponding pressure change to determine if an EVAP system leak is present. The EONV diagnostic is designed to detect leaks as small as 0.51 mm (0.20 in). The diagnostic can determine if a small leak is present based on vacuum or pressure readings in the EVAP system. When the EVAP system is sealed a finite amount of pressure or vacuum will be observed. When a 0.51 mm (0.20 in) leak is present, little or no pressure or vacuum is observed. If the test reports a failing value, DTC P0442 will set.

far2grumpy

07-09-2009, 02:42 PM

RobertGary1

At the risk of providing information you might already have ... I've attached one battery drain document ... referencing the 2003 model year (MY).

There's another document for the 2005 MY but is slightly too large to post to forum. I'll email if you'll send address by PM.

You'll note neither is specifically for the 06 model year but I suspect most of the data will carry over to newer vehicles.

Its particularly interesting to note a 25 minute (approximate) power down delay for the class 2 devices (BCM, ECM, etc.) referenced in the 03 document.

fdryer

07-09-2009, 03:07 PM

"Dampness" - could this possibly mean leaking (battery acid) terminals from damage? Make up a small cup of hot water and baking soda, dissolved, and toothbrush it on the dampness; if this solution bubbles up, battery acid is leaking out somehow (baking soda/water neutralizes battery (sulphuric) acid and if leaking enough may have leached into the battery cables to eat up the copper wiring. Loss of copper wiring can result in less gauge wire for supplying the welding currents needed to power a starter. A damaged battery leaking acid to ruin battery cables was supposed to have been a past issue with early AC Delco batteries. Battery and/or cable(s) may have to be replaced if it has gone this far.......

BobbyP

07-09-2009, 04:03 PM

Your OEM battery is almost or is four years old... My bets are it's done it's time. Replace it with another quality battery.

Your estimates of current draw is assuming you have a healthy battery, it's four years old. IMO that's great service for an OEM battery...

Keep in mind that your OnStar transmits data periodically. At least once a week. I'm not sure if this still happens on cars that cancel OnStar...

far2grumpy

07-09-2009, 05:49 PM

I can't say for sure about the 06, but in earlier models the EVAP system is monitored for awhile after a drive cycle.

3RedLines ... if we had to pay to be forum members I'd help pay your subscription to keep you around!!!

You can stay but I think the puddy-tat needs to go on feline equivalent of a Slim-Fast diet.

On a positive note it appears there are no rodents within miles of your abode.

3RedLines

07-09-2009, 06:23 PM

Thanks!! I'll be here for quite some time, The Wife says our 6 Vues will have to last for the rest of our lives :yes:

Can't put the kitty on a diet or she turns into.....
http://www.saturnfans.com/forums/image.php?u=61561&dateline=1245525543&type=profile
Bad Kitty!!!!

xtremeranger

07-09-2009, 06:39 PM

yeah, four years+...its probably time....try it with a different battery...

chillin05VUE

07-09-2009, 07:32 PM

Just curious, I know you said that everything is factory and nothing aftemarket, but did you have a Lo-Jack installed? I know that Lo-Jacks will kill a battery if attached to the wrong circuit such as a dome light or anything that's controlled by the BCM. And after 8 hours sounds about the time needed for it to drain a battery.

BTW, how's my old stumping grounds of Sacramento?

BobbyP

07-09-2009, 07:40 PM

xtremeranger

07-10-2009, 01:37 AM

Today my VUE's electric cooling fan ran for about 5 minutes after I parked from the high temps.

I'm sure it drew quite a bit of power during that episode. I can imagine that could kill a marginal battery.

Mine does that too esp down here in the south where the temp is 98-100 with a heat index of 105.....:snide:....and after I run her hard during that time...

I think thats pretty cool tho, make some folks think its a turbo timer.. :P

neilpilot

07-10-2009, 11:47 AM

Visual: Looked over the battery connection and other than a slight amount of chalking didn't see anything bad. Noted as interesting a small amount of "dampness" around both terminal posts though. Not sure why.

At 4-years old, if the battery passed the load test then something else is draining the charge. If there's sufficient dampness across the terminals, a battery in storage will "short" and dicipate it's charge over a relatively brief period.

RobertGary1

07-10-2009, 03:07 PM

I charged the battery yesterday afternoon and left it on the bench and by this morning found it to be down to 8 volts. Also noted that the battery was warm. So somehow this thing has shorted internally and is eating itself. Now I can put a $100 battery in the car and not worry that its not the problem. :) Interesting that even at 8 volts it still performed pretty well on a load test. Its certainly carrying a charge, its just slowly turning it into heat.

BobbyP

08-01-2009, 02:36 PM

What was the conclusion to this problem?

I hate cliffhangers ... :)

Snip from Wikipedia for those not familiar with early plot complications...

A cliffhanger or cliffhanger ending is a plot device in fiction which features a main character in a precarious or difficult dilemma, or confronted with a shocking revelation. A cliffhanger is hoped to ensure the audience will return to see how the characters resolve the dilemma.

The phrase is believed to come from the end-of-episode situation in adventure silent films of the early 1900s days, with the protagonist literally left hanging from the edge of a cliff, although the oldest usage the Oxford English Dictionary has is from 1937. Some serials end with the caveat "To be continued", or "The End?" In television series, the following episode usually begins with a recap (a.k.a. "previously").

RobertGary1

08-31-2009, 01:57 PM

What was the conclusion to this problem?

I hate cliffhangers ... :)

Looks like my guess that the battery had shorted itself was probably right. Replaced the battery and the problem went away. That was certainly the most diagnosing I've ever done for a simple battery problem though! Not the way in which I've had batteries fail before.

tcndeb

08-31-2009, 05:53 PM

I just went through the same situation on my '92 full size Blazer. Had an Optima Red Top in it, and I drove myself around the bend looking for a discharge, because it just COULDN'T be that high dollar battery, that was only two years old. My '04 Vue still has the factory battery in it, so I'll probably replace it before winter kicks in.

BTW, hello from another Sacramento ex. Well, North Highlands to be exact, but close enough.

BobbyP

08-31-2009, 07:02 PM

Thx... I can now get a good nights sleep... :)

The OEM Delco battery seems to work well in the VUE.

I'm probably going to try and get the same battery again when my VUE's battery dies...

VTchemist

08-31-2009, 08:55 PM