Batt dead after sitting for a week
06-04-2013, 06:25 AM
#17
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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.
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.
06-04-2013, 11:23 AM
#18
Electron Wrangler
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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.
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.
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
06-04-2013, 11:39 AM
#19
Chronic Tool Dropper
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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.
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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.
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.
06-04-2013, 03:48 PM
#20
Nordschleife Master
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.
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.
06-09-2013, 09:24 PM
#21
Race Car
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
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
06-10-2013, 02:57 PM
#24
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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.
06-10-2013, 02:59 PM
#25
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06-10-2013, 04:32 PM
#27
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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.
06-10-2013, 05:18 PM
#28
Burning Brakes
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
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
06-10-2013, 07:12 PM
#29
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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.
06-10-2013, 10:26 PM
#30
Nordschleife Master
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.
I suspect issues with aftermarket alarm and/or flaky pin switches.
