Help Please Electrical Question
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,675
Likes: 13
From: Sudbury MA
Help Please Electrical Question
Long ago someone told me there was a way to check for a slow drain on a battery by hooking up a meter from the positive battery terminal to a ground ( I think ??) to see if something was causing a slow drain. Not sure if I got this right since it has been many years since I've done it and memory is getting fuzzy.
Can someone tell me how using a meter I can check for a slow drain to see what is discharging a two year old battey on a neighbor's car.
I use Battery Tenders on all my vechiles so I never have the problem but I can't remember the proper way to do this test.
Thanks for any help
Kurt
Can someone tell me how using a meter I can check for a slow drain to see what is discharging a two year old battey on a neighbor's car.
I use Battery Tenders on all my vechiles so I never have the problem but I can't remember the proper way to do this test.
Thanks for any help
Kurt
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Disconnect the neg cable and then put your meter between the neg cable and the neg battery post. If it shows less than 12 volts, then the draw is too small to worry about. If it shows battery voltage, BTW make sure the doors are closed so the dome light is not on, then there is a drain. If you have an amp setting on the meter you can tell how much current is being used. The procedure is to remove fuses 1 at a time to see which circuit is the culprit. The amp setting is useful so you can see your progress as you eliminate problems. For example if there is more than 1 circuit causing a drain. Things like the clock or stereo memory may show battery voltage, but he amperage is so low that it would take months to drain the battery.
Last edited by '75; Mar 2, 2008 at 10:18 AM.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Not to bust on anyone, but your not checking for Voltage in this test, but for Current.
I do this test on the + side, just because. As stated, disconnect the cable and set the meter for Amps, most will do 10 amps so start on that scale, then turn it gown to get in the correct range. Connect the meter between the cable and the battery.
close the doors, make sure everything is off and wait for the timer to turn the lights off.
You should be reading something less than 300ma, thats mili amps or 1000 ths of an amp, pretty small
If its doing more than that you may have a problem. Start by disconnecting the alternator, that will eliminate any bad diodes that coule be the culprit.
Then remove the fuses one at a time (don't put them back in) and see if it goes away
The CTSY circuit is a common offender
I do this test on the + side, just because. As stated, disconnect the cable and set the meter for Amps, most will do 10 amps so start on that scale, then turn it gown to get in the correct range. Connect the meter between the cable and the battery.
close the doors, make sure everything is off and wait for the timer to turn the lights off.
You should be reading something less than 300ma, thats mili amps or 1000 ths of an amp, pretty small
If its doing more than that you may have a problem. Start by disconnecting the alternator, that will eliminate any bad diodes that coule be the culprit.
Then remove the fuses one at a time (don't put them back in) and see if it goes away
The CTSY circuit is a common offender
6th Gear
Joined: Nov 2005
Posts: 6
Likes: 0
Documented Procedure for Identifying Curcuit Drain
Here is a pdf for a test procedure that was posted in an another thread. Hope it helps.
http://photos.imageevent.com/durango...%20Testing.pdf
http://photos.imageevent.com/durango...%20Testing.pdf
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,675
Likes: 13
From: Sudbury MA
Thank you gentlemen
That's exactly the test I was referring to but I forgot exactly how to hook it up and the fact that the cable must be disconnected from the battery and that the test light or meter needs to be connected in between.
I appreciate the quick replies
This forum is awesome
Kurt
That's exactly the test I was referring to but I forgot exactly how to hook it up and the fact that the cable must be disconnected from the battery and that the test light or meter needs to be connected in between.
I appreciate the quick replies
This forum is awesome
Kurt
Last edited by ksbunting; Mar 2, 2008 at 10:47 AM.
Racer
Joined: Dec 2002
Posts: 319
Likes: 3
From: santa clara ca
When I check for a drain i connect a test light between the neg cable and the neg post. I then remove one fuse and check the light if light stays on i remove another fuse and if light goes out you found the drain check owners manual for what devices work off the fuse and start checking for a grounded circuit.
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,675
Likes: 13
From: Sudbury MA
You won't believe what I found when I checked the battery.
Battery has top posts and side posts.
Car with 34,000 miles has been sitting in heated garage for last 9 months without use. My friend bought a battery charger and hooke dit up and it did nothing, didn't even move the gauge.
Reason: car's cables were hooked up to side posts and he hooked up the battry charger to the top posts RIGHT OVER THE PROTECTIVE PLASTIC CAPS. Been on the charger for days and did nothing excpet make for very good insulation.
I hooked the charger up properly, waited 15 minutesd and started it right up.
Gotta love it
Kurt
Battery has top posts and side posts.
Car with 34,000 miles has been sitting in heated garage for last 9 months without use. My friend bought a battery charger and hooke dit up and it did nothing, didn't even move the gauge.
Reason: car's cables were hooked up to side posts and he hooked up the battry charger to the top posts RIGHT OVER THE PROTECTIVE PLASTIC CAPS. Been on the charger for days and did nothing excpet make for very good insulation.
I hooked the charger up properly, waited 15 minutesd and started it right up.
Gotta love it
Kurt
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Joined: Jan 2001
Posts: 16,221
Likes: 118
From: Matthews NC
You won't believe what I found when I checked the battery.
Battery has top posts and side posts.
Car with 34,000 miles has been sitting in heated garage for last 9 months without use. My friend bought a battery charger and hooke dit up and it did nothing, didn't even move the gauge.
Reason: car's cables were hooked up to side posts and he hooked up the battry charger to the top posts RIGHT OVER THE PROTECTIVE PLASTIC CAPS. Been on the charger for days and did nothing excpet make for very good insulation.
I hooked the charger up properly, waited 15 minutesd and started it right up.
Gotta love it
Kurt
Battery has top posts and side posts.
Car with 34,000 miles has been sitting in heated garage for last 9 months without use. My friend bought a battery charger and hooke dit up and it did nothing, didn't even move the gauge.
Reason: car's cables were hooked up to side posts and he hooked up the battry charger to the top posts RIGHT OVER THE PROTECTIVE PLASTIC CAPS. Been on the charger for days and did nothing excpet make for very good insulation.
I hooked the charger up properly, waited 15 minutesd and started it right up.
Gotta love it
Kurt
