How to find a parasitic draw
Battery went dead. I put in new battery. After 5 days battery is dead and must jump start.Dealer has had car for 2 weeks. This is their 3rd failure to find the problem. I don't think they know what to do.
They first thought it was the radio and unplugged it. Still ran down in 5 days. Anybody know what the problem could be and how to fix?? Thanks, for your help, Mike
Answer:
How to find your battery drain
Parasitic Draw Test
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How to Find a Parasitic Battery Drain
When your car battery goes dead overnight, usually either the battery is at the end of its life span, or you left something on, such as a light. Occasionally something is drawing power that’s not of your doing. This is a parasitic draw, and it can cause the same result as leaving the headlights on: a dead battery in the morning.
Steps
-Remove the negative side battery cable from the negative battery terminal.
-Attach an ammeter(this measures amperage) between the negative cable and the negative battery post. wait a few seconds to several minutes for the car to go into sleep mode. i.e. when you make the contact with the test light the cars computer systems "wake up" after a bit of time they will go to "sleep".
If the ammeter is reading over 25-50 milliamps, something is using too much battery power.
-Go to the fuse panel(s) and remove fuses, one at a time. Pull the main fuses (higher amp ratings)last. Be sure to observe the ammeter after pulling each fuse.
-Watch for the ammeter to drop to acceptable drain. The fuse that reduces the drain is the draw. Consult the owners' manual or service manual to find what circuits are on that fuse.
-Check each device (circuit) on that fuse. Stop each lamp, heater, etc. to find the drain.
-Repeat steps 1&2 to test your repair. The ammeter will tell you exact numbers.
NOTE: The original author listed this repair using a 12v test light. The best place for your test light is the trash. A test light doesnt measure voltage; it shows if enough voltage is present to light the lamp.
An ammeter meaures current (in amps), and that is what you are fighting against if you have a parasitic drain problem.
Tips
A parasitic drain is when an electrical device is using battery power when the car is closed, and the ignition key removed. Therefore, when doing this test make sure that the dome light, under hood light, trunk light, etc. are off.
Warnings
Don't forget to check inside cigarette lighter and power sockets. Sometimes coins can fall in and cause shorts.
Some after-market alarm systems may make this test too long or loud to be worth the effort. If that's the case, seek professional help.
In more and more models made after 2003 disconnecting the battery will reset the PCM requiring the modules to relearn. In certain cases this requires a factory scan tool. It is best to take such cars to either the dealer or a professional in auto electrical systems.
Things You'll NeedA digital multimeter or ammeter.
A fuse puller.
Any tools needed to access battery and fuse panel(s).
An owners' manual or maintenance manual showing electrical circuits.
I have a 2004 Lincoln Aviator bought used this spring. We had to have the air fixed on it and it seems that since then (hubby says my imagination) we are getting a drain on the battery. If it sits more than a day, it needs a boost. Took to Ford dealership and they said I needed a new battery. Got new battery and a month later, problem started again. Took it back and this time they said battery had a bad cell, so replaced battery. A couple of months later it did it again. This time told them to keep it till they found the problem! Came back after apparently consulting with Ford and said the Electronic Automatic Temperature Control module needed replacing. Did this last week and 4 days later, guess what? Battery dead again! Do you have any ideas? Frustrated in London, Ontario, Canada.
Hi my name is XXXX XXX I'll help you today. Its hard to tell without testing the truck what is causing the draw on the battery. It is very unlikely that fixing the air would have anything to do with the concern happing to you now. You have a draw on the electrical system causing the battery to die. It sounds like you had the car tested for this and they found a draw on the EATC circuit. Unfortunately it sounds like they did not pick the correct component causing the draw. You need to bring it back to where the work was perform and have them continue to test for the draw. Thats the only thing that would be causing the problem your having its now just a matter of testing to see what is causing the problem. Jeff
Apparently each time the car has been there, they have tested and retested for draws. The alternator and starter are fine and whatever other tests they did. Can you give me an idea as to what I could ask them to look for? The last "fix" cost me over $1,100!!
The spec on your truck for a draw is .05v see if this compares with what your truck has. Also depending on how fast you truck is dieing now I have seen alternators charging system check fine but have an intermittent draw in them when the engine is off and this did not show up on my meter. Hope this helps you...... Jeff
Expert: JEARL8
Pos. Feedback: 100.0 %
Accepts: 7
Answered: 12/28/2010
ASE Certified Technician
Sounds like a parisitic draw. You can only check for that with an external probe on computer controled vehicles just for info. Here is what you can do though. Disconect the battery and then disconect the "B" terminal that is conected to the Alternator. That is the big 8 guage cable leading to the positive post from the alternator. Put something over it so when you reconect the battery it doesn't short to ground. Reconect the battery and see if the drain is still there. If the drain is gone your most likely cause is a shorted alternator. And yes I have come across alternators that charge the vehicle, but have a parisitic draw due to a defect. From what you described on the voltage drop when the battery is connected, it is a big short. If your positive cable is touching ground somewhere, that would cause it too, but most likely would melt at that area. Suspect your alternater!!
