Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

Batt dead after sitting for a week

 
Old 06-04-2013, 06:03 AM
  #16  
Nicole
Cottage Industry Sponsor
Lifetime Rennlist
Member
 
Join Date: Oct 2001
Location: Silly Valley, CA
Posts: 25,300
Default

Glad you found the culprit. When this happened on my car, it turned out to be the switch for the engine light under the hood.
Nicole is offline  
Old 06-04-2013, 06:25 AM
  #17  
Bill Ball
Under the Lift
Lifetime Rennlist
Member
 
Bill Ball's Avatar
 
Join Date: Mar 2002
Location: Buckeye, AZ
Posts: 18,467
Default

Originally Posted by danglerb View Post
Messing with my wife's Lincoln, draw on the battery at idle was -56 amps, initial key off 2.5 amps, 30 sec drops to about 50 ma, five min or so 17 ma, bit over half an hour 1 ma or less.

I forget how long it is before the brain goes fully asleep on the 928, but I did come up with the idea of using a spare hatch lock so I can leave the hatch open during testing. For now I use a battery disconnect on the ground strap.

DC clamp meter is a handy item, good ones are expensive, but the Craftsman 82369 will zero down to about 10 ma and goes on sale around $60.
The brains go to sleep immediately. For the early 928s, draw should drop to baseline immediately if the interior lights are off, doors closed. Beginning with the S4 models there is some extra draw for 45 minutes after the ignition is turned off by the engine cooling fan control module.
Bill Ball is offline  
Old 06-04-2013, 11:23 AM
  #18  
Alan
Electron Wrangler
Lifetime Rennlist
Member
 
Alan's Avatar
 
Join Date: Mar 2002
Location: Phoenix AZ
Posts: 11,930
Default

Originally Posted by danglerb View Post
Messing with my wife's Lincoln, draw on the battery at idle was -56 amps, initial key off 2.5 amps, 30 sec drops to about 50 ma, five min or so 17 ma, bit over half an hour 1 ma or less.

I forget how long it is before the brain goes fully asleep on the 928, but I did come up with the idea of using a spare hatch lock so I can leave the hatch open during testing. For now I use a battery disconnect on the ground strap.

DC clamp meter is a handy item, good ones are expensive, but the Craftsman 82369 will zero down to about 10 ma and goes on sale around $60.
Easier is to pull the connector for the Brown/White wire off the bottom of the hatch reciever (disable interior lights from hatch). Then tape the pin switch in for the passenger door so you have access to the CE panel for testing.

If you don't keep the interior lights off you will likely blow your DMM fuse while testing. If you do this you discover that the fuses they use are hard to get in a hurry (buy 2-3 replacements so you are ready next time).

A DC clamp meter is a hard to source beast - and not the ideal tool for this due to its accuracy at very low current levels. Its a handy thing to have for other reasons though.

Alan
Alan is offline  
Old 06-04-2013, 11:39 AM
  #19  
dr bob
Chronic Tool Dropper
Lifetime Rennlist
Member
 
dr bob's Avatar
 
Join Date: Oct 2001
Location: Bend, Oregon
Posts: 17,818
Default

FWIW, I made a 'test harness' for the Harbor Freight fuse-panel plug-in ammeter. http://www.harborfreight.com/30-amp-...ter-67724.html

I used a common in-line fuse holder with pigtails, added spades and clips. Plug the tester into the fuse socket in the in-line fuse holder and voila! I put a spare 10A fuse in the tester itself. The tester itself reads down to 10mA per the instructions/specs.

There's a smaller 20A capacity tester. It has the connector needed for the even smaller fuses, so isn't appropriate for the 928 fuse panel connections.

---

I 'tested' the drain with this tool, compared it with the reading on the Fluke and also to what the el-cheapo ride-along DMM reads. All three are close at a little less than 20mA on the Fluke, with the other two showing 20mA due to display resolution.
dr bob is offline  
Old 06-04-2013, 03:48 PM
  #20  
danglerb
Super User
 
danglerb's Avatar
 
Join Date: Oct 2006
Location: Orange, Cal
Posts: 8,549
Default

Fuse Buddy is the original fuse meter and also comes as an adapter for a DMM for about $13 on Amazon etc. with fuse holder test lead connection ready to use.

I hate running current through any meter, much better IMHO to use an external shunt and measure the current indirectly as a voltage drop.

I agree the cheap Craftsman 82369 has fairly limited accuracy, as I said zero to about 0.01 amp on the 40A low range, and it does have some wiggle at that, but if you have a 928 down to a 10 or 20 ma drain I think you are golden. 99% of the rest of the time this meter does a dandy job, and once you use a DC clamp you will wonder how you got along without one.
danglerb is offline  
Old 06-09-2013, 09:24 PM
  #21  
michaelathome
Super User
 
michaelathome's Avatar
 
Join Date: Nov 2004
Location: Chantilly VA
Posts: 4,455
Default

I am also trying to find a baseline. My WIP '89 sits at 13.0mA with the alarm on, based on the above volt meter settings. Currently my clock nor the head unit are plugged in.

From reading the thread am I looking at 15-18mA once my head unit is hooked up and the clock is on? Does that sound about right for a baseline?

Michael
michaelathome is offline  
Old 06-09-2013, 09:30 PM
  #22  
michaelathome
Super User
 
michaelathome's Avatar
 
Join Date: Nov 2004
Location: Chantilly VA
Posts: 4,455
Default

Originally Posted by Bill Ball View Post
Normal 30-35ma.
Cool, didn't read enough I guess.

Thanks Bill!

michaelathome is offline  
Old 06-09-2013, 10:08 PM
  #23  
Jfrahm
Addict
Rennlist Member

 
Jfrahm's Avatar
 
Join Date: Mar 2002
Location: Boulder, CO
Posts: 5,745
Default

How can you disable the fan controller for testing?
Jfrahm is offline  
Old 06-10-2013, 02:57 PM
  #24  
Bill Ball
Under the Lift
Lifetime Rennlist
Member
 
Bill Ball's Avatar
 
Join Date: Mar 2002
Location: Buckeye, AZ
Posts: 18,467
Default

Originally Posted by michaelathome View Post
Cool, didn't read enough I guess.

Thanks Bill!

Actually, I couldn't locate the expected draw in the WSM today or any of the tech documents. With search I saw Wally posted 20 mA, but my recollection is 30 mA. I don't think I've seen lower than that, and, of course, often much higher. A few cars have been a pain to get below 50, but I think less than 30 is a very good target.
Bill Ball is offline  
Old 06-10-2013, 02:59 PM
  #25  
Bill Ball
Under the Lift
Lifetime Rennlist
Member
 
Bill Ball's Avatar
 
Join Date: Mar 2002
Location: Buckeye, AZ
Posts: 18,467
Default

Originally Posted by Jfrahm View Post
How can you disable the fan controller for testing?
Usually just let the car sit for 45 minutes. I'm not sure if unplugging the final stage in front of the engine compartment will kill the draw.
Bill Ball is offline  
Old 06-10-2013, 03:04 PM
  #26  
Hollisterkiid92
User
 
Hollisterkiid92's Avatar
 
Join Date: Mar 2013
Location: Duncanville, Tx
Posts: 334
Default

I have a new battery, extreme plus by O'Reilly, I bought new and have no need If u need it it ill sell it cheap, it cost me 150
Hollisterkiid92 is offline  
Old 06-10-2013, 04:32 PM
  #27  
Jfrahm
Addict
Rennlist Member

 
Jfrahm's Avatar
 
Join Date: Mar 2002
Location: Boulder, CO
Posts: 5,745
Default

Originally Posted by Bill Ball View Post
Usually just let the car sit for 45 minutes. I'm not sure if unplugging the final stage in front of the engine compartment will kill the draw.
I was thinking this module might lose it's ability to self-shutoff and cause a draw. I have found that the murfmobile has a pretty good battery drain, but after pulling out or disabling anything I could I still did not find it. I might have been within the 45 minute window.
Jfrahm is offline  
Old 06-10-2013, 05:18 PM
  #28  
jheis
User
 
jheis's Avatar
 
Join Date: Sep 2003
Location: Wine Country, CA
Posts: 1,149
Default

I've got the same problem with my '89. Something is draining the battery - intermittently. It will be fine for a week or two and then it will go completely flat overnight - so flat that I can't even jump it with a battery pack.

Checked the current draw at each fuse and the only one with any draw is fuse #24 which shows .2 amps (goes up to .5 if I open the glove box door).

I've taken to disconnecting the battery ground strap when ever I park it overnight - to avoid the nasty surprise of a dead battery in the morning when I have to be somewhere...

James
jheis is offline  
Old 06-10-2013, 07:12 PM
  #29  
RKD in OKC
Addict
Rennlist Member
 
RKD in OKC's Avatar
 
Join Date: Oct 2004
Location: In a tizzy
Posts: 4,970
Default

Had a 24 hour set and dead battery on my 90 GT after a stereo upgrade. Turned out the glove box latch was loose. Looked closed but not enough to trip switch to turn off the bulb in the glove box.
RKD in OKC is offline  
Old 06-10-2013, 10:26 PM
  #30  
danglerb
Super User
 
danglerb's Avatar
 
Join Date: Oct 2006
Location: Orange, Cal
Posts: 8,549
Default

I've debated instead of fixing all the drains, to swapping all the lamps for low current LED replacements.

I suspect issues with aftermarket alarm and/or flaky pin switches.
danglerb is offline  
 


Thread Tools
Search this Thread
Quick Reply: Batt dead after sitting for a week


Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: