Parasitic Drain?
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Parasitic Drain?
I just went to my buddy's house in my C3. We talked for about two hours. I got in the car and it would do nothing but click once when I turned the key. We jump started it and it fired right up.
I have a fairly new battery that I leave on a tender when the car sits. The amp gauge shows a charge when driving. I've checked the starter connections and everything is tight.
I'm tired of having to pull out my jumper cables whenever I stop somewhere where she sits for a short period of time.
I thought I had fixed the problem but it keeps coming back. I've checked my neutral safety switch and have even gone as far as replacing and adjusting the ignition switch.
Help please. I'm no electrical guru so tell me what to check and how to get to the bottom of this.
'81 with auto
I have a fairly new battery that I leave on a tender when the car sits. The amp gauge shows a charge when driving. I've checked the starter connections and everything is tight.
I'm tired of having to pull out my jumper cables whenever I stop somewhere where she sits for a short period of time.
I thought I had fixed the problem but it keeps coming back. I've checked my neutral safety switch and have even gone as far as replacing and adjusting the ignition switch.
Help please. I'm no electrical guru so tell me what to check and how to get to the bottom of this.
'81 with auto
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Its not heat soak to the starter since it turns right over with the help from a healthy battery. You can start diagnosis with a DMM. Check the battery voltage before you try starting it. 12.6 before you start it, then 13.7 to as high as 14.7 running. It won't take much drop from 12.6 to have a big impact on the starter circuit.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
I remember you had a similar problem before. It might be possible that the new battery you bought is defective as it seemed to work fine when you got everything straightened out.
Last edited by CanadaGrant; Nov 29, 2016 at 12:10 AM.
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
Its not heat soak to the starter since it turns right over with the help from a healthy battery. You can start diagnosis with a DMM. Check the battery voltage before you try starting it. 12.6 before you start it, then 13.7 to as high as 14.7 running. It won't take much drop from 12.6 to have a big impact on the starter circuit.
If the alt is putting out, suspect bad battery or bad battery connections
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Hey CanadaGrant you have a good memory.
I am puzzled as this has been an ongoing problem.
I will be doing some testing this afternoon and will post the results.
Until then it's - "Have jumper cables will travel."
Pro
Joined: Dec 2004
Posts: 710
Likes: 2
From: Raynham MA
I recently had an issue with my battery on my 72. I only had the car for a few months so I just bought a new battery. I would take it out and drive to a store.. then it wouldnt start in the parking lot.. 2 weeks later with the new battery I started having issues starting the car again.. After using a multimeter and determining I didn't have anything significant draining the battery.. I looked to the alternator.. When examining the positive cable on the back of the alternator it pulled right off in my hand.. so for me it was just a bad connection.. All is good now.. Battery reads at 14.4 with car running.. Might be worth double checking your connections.
Racer
Joined: Jun 2012
Posts: 279
Likes: 14
From: New Britain Connecticut
everyone always says clean the negative battery terminal connection. for me it was the positive battery cable had a wear mark in it from hitting the drive shaft. although it tested fine the cable could not always transmit full voltage. Just an idea
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
Might be a good idea to get under the car and check the integrity of the POS cable to the starter and check the NEG cable to the frame. I have seen some wicked NEG cables that were all kinds of shredded and just were not capable of carrying the load.
Last edited by Mark Riles; Nov 29, 2016 at 11:34 AM.
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Burning Brakes
Joined: Jul 2016
Posts: 767
Likes: 74
From: Blaine MN
I'd suggest disconnecting the Battery after your next drive (you didn't say how long the drive needs to be for the problem to occur), and then do your x hour break, hook back up and see if it starts (to verify parasitic loss). You can monitor Battery Voltage but it really doesn't tell you about your cranking capacity, if your charging system isn't working correctly (over/under charging) it can slowly degrade battery cranking capacity. Two hours and no start would take a fair parasitic drain to prevent starting with a good battery. A small drain (0.x-10A) is detectable with a DMM (if your meter is DC Amp capable, usually 10A max), milli/micro amp drains can be found by placing the Voltmeter (DC Volt range) between the battery post and a disconnected cable end.
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
it could be the starter solenoid, it might need to be taken apart and cleaned with emery cloth on the contacts, easy fix other than pulling the starter, I would also replace the brushes in the starter and clean to contacts in it also. easy and doesn't cost much. DO NOT just replace the starter. you will probably get junk. find someone to help you do this, it will a great learning experience!!!
Burning Brakes
Joined: Oct 2015
Posts: 781
Likes: 113
Have you put the ammeter on the detached from battery negative cable with ALL OFF and seen any current draw?.IF so..pulling fuses one at a time will show which part of the electrical system is drawing current when it isn't supposed to..Aside from maybe an electric clock..does your 81 have an alarm system? I had problems with my '78 that had some faulty connection spots in the fact alarm system..I disconnected the alarm system..and the parasitic discharge problem disappeared forever..jim
Last edited by jim in oregon; Nov 30, 2016 at 02:51 PM.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
My dvm failed. Just got a new one. I have the dvm hooked up to the battery now. I'm checking D.C. Voltage at the battery now. It started at 13.0. I'm waiting to see if the voltage drops over a period of time.
I took the negative cable off at a car show recently. When I reconnected the battery it started with no problem. We were there for a few hours.
Checked all starter and alternator connections today. Everything tight.
I took the negative cable off at a car show recently. When I reconnected the battery it started with no problem. We were there for a few hours.
Checked all starter and alternator connections today. Everything tight.
Last edited by Street Rat; Dec 3, 2016 at 11:45 AM.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
I have an aftermarket alarm system. It does have some 12 v constant connections. I have had problems starting whether the alarm has been set or not. Those connections should not prevent starting after two hours though.
Going to try the suggestions here next.
Going to try the suggestions here next.
Thread Starter
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Originally Posted by lvmyvt76
it could be the starter solenoid, it might need to be taken apart and cleaned with emery cloth on the contacts, easy fix other than pulling the starter, I would also replace the brushes in the starter and clean to contacts in it also. easy and doesn't cost much. DO NOT just replace the starter. you will probably get junk. find someone to help you do this, it will a great learning experience!!!
On to testing.
Instructor
Joined: Aug 2016
Posts: 235
Likes: 28
From: Fort McMurray Alberta
StreetRat,
Let's start with the basics and verify you have a drain. We can put a DVOM in play to check the Ma or AMP draw but something simple is a 12 VDC test light in series with the NEG circuit.
Disconnect the NEG cable from the battery. Clip one end of the test light to the NEG terminal of the battery and the other end to the clamp on the NEG cable. So essential you have the test light between the NEG cable and the NEG terminal of the battery.
The light should be off as in nothing running through the system when the key is off.
If the light is on then you have a drain. The light will be brighter according to the amount of draw on the system. Example. Very bright if you turn your headlights on and fairly dim if you have a single interior light on.
Cheers,
Ryan
Let's start with the basics and verify you have a drain. We can put a DVOM in play to check the Ma or AMP draw but something simple is a 12 VDC test light in series with the NEG circuit.
Disconnect the NEG cable from the battery. Clip one end of the test light to the NEG terminal of the battery and the other end to the clamp on the NEG cable. So essential you have the test light between the NEG cable and the NEG terminal of the battery.
The light should be off as in nothing running through the system when the key is off.
If the light is on then you have a drain. The light will be brighter according to the amount of draw on the system. Example. Very bright if you turn your headlights on and fairly dim if you have a single interior light on.
Cheers,
Ryan
Pro
Joined: Feb 2012
Posts: 577
Likes: 6
The light should be off as in nothing running through the system when the key is off.
If the light is on then you have a drain. The light will be brighter according to the amount of draw on the system. Example. Very bright if you turn your headlights on and fairly dim if you have a single interior light on.
If the light is on then you have a drain. The light will be brighter according to the amount of draw on the system. Example. Very bright if you turn your headlights on and fairly dim if you have a single interior light on.
Make sure the door is closed, and you are either in the car or leaning over the door. If the courtesy light system is activated by an open door then obviously the test light will indicate the draw. The test light method only works if the door is closed. If the test light is lit while the doors are closed, then you indeed have a drain. At this point the not fun work begins if you are old and fat like me. No you need to start pulling fuses one by one until the test light is not lit. Basically, pull a fuse and close the door. If the test light is lit, open the door, put that fuse back in, and pull the next one. Eventually you will pull the fuse of the circuit that might be draining the battery. That will help you narrow down where to look for said drain.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
Make sure the door is closed, and you are either in the car or leaning over the door. If the courtesy light system is activated by an open door then obviously the test light will indicate the draw. The test light method only works if the door is closed. If the test light is lit while the doors are closed, then you indeed have a drain. At this point the not fun work begins if you are old and fat like me. No you need to start pulling fuses one by one until the test light is not lit. Basically, pull a fuse and close the door. If the test light is lit, open the door, put that fuse back in, and pull the next one. Eventually you will pull the fuse of the circuit that might be draining the battery. That will help you narrow down where to look for said drain.
Racer
Joined: Apr 2016
Posts: 493
Likes: 65
StreetRat,
Let's start with the basics and verify you have a drain. We can put a DVOM in play to check the Ma or AMP draw but something simple is a 12 VDC test light in series with the NEG circuit.
Disconnect the NEG cable from the battery. Clip one end of the test light to the NEG terminal of the battery and the other end to the clamp on the NEG cable. So essential you have the test light between the NEG cable and the NEG terminal of the battery.
The light should be off as in nothing running through the system when the key is off.
If the light is on then you have a drain. The light will be brighter according to the amount of draw on the system. Example. Very bright if you turn your headlights on and fairly dim if you have a single interior light on.
Cheers,
Ryan
Let's start with the basics and verify you have a drain. We can put a DVOM in play to check the Ma or AMP draw but something simple is a 12 VDC test light in series with the NEG circuit.
Disconnect the NEG cable from the battery. Clip one end of the test light to the NEG terminal of the battery and the other end to the clamp on the NEG cable. So essential you have the test light between the NEG cable and the NEG terminal of the battery.
The light should be off as in nothing running through the system when the key is off.
If the light is on then you have a drain. The light will be brighter according to the amount of draw on the system. Example. Very bright if you turn your headlights on and fairly dim if you have a single interior light on.
Cheers,
Ryan
If you think a battery draw is hard on a car, try doing it on a 40' motorhome. I worked on RV's after I retired from the military for almost 10 years. I learned a lot in that time.
Last edited by USAFVeteran; Dec 1, 2016 at 11:25 AM.
Racer
Joined: Apr 2016
Posts: 493
Likes: 65
Make sure the door is closed, and you are either in the car or leaning over the door. If the courtesy light system is activated by an open door then obviously the test light will indicate the draw. The test light method only works if the door is closed. If the test light is lit while the doors are closed, then you indeed have a drain. At this point the not fun work begins if you are old and fat like me. No you need to start pulling fuses one by one until the test light is not lit. Basically, pull a fuse and close the door. If the test light is lit, open the door, put that fuse back in, and pull the next one. Eventually you will pull the fuse of the circuit that might be draining the battery. That will help you narrow down where to look for said drain.
Again, to add:
You can over ride the door switch so you don't have to keep opening and closing the door. Duct tape, clamp, something to hold the button in while the door is open