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Discussion Starter · #1 ·
Hopefully someone here has resolved what appears to be many taurus owners suffering from a dead battery after the car sits. I have done extensive searching and have found at least 50 different posts of owner with this issue. I have yet to find anyone that has resolved it. The car runs fine and no lights are on. The battery has just been replaced for the second time in 6 months. The GEM has been replaced, the door switches have all been lubricated and the ABS module connector has been cleaned and filed with dielectric grease. Every time I test the amp draw at the battery it pulls 120ma for 40 minutes and then drops to 20ma. How does the battery get drained by a 20ma draw overnight. Is there something else that could drain the battery without showing on the multimeter? This car belongs to my inlaws and only has 77k on it. The alternator has been tested and is good. The battery is being charged at 14.5 volts when the car is running. I'm tired of getting the same 20ma reading but dealing with a dead battery. Somebody please help.
 

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20 mA draw after 40 min is good. The "early" draw of 120 mA is typical, as some modules stay awake for a while after the key is turned off. If the draw test was done correctly, there is nothing else that will cause a draw that wont show up on the amp meter. I am guessing bat batt. I know it has been replaced twice, but I have had a few new batts over the last 35 years that lasted a week before failing. One lasted a day before failing.
 

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Discussion Starter · #3 ·
Thanks for the reply, Maybe I'm doing the draw test wrong? I'm just unhooking the positive cable and connecting one lead to the cable end and the other to positive post of the battery. Like you said these numbers are on the money for the car working correctly. The deal is that if I pull the main 40 amp fuse for the interior electrical the battery will not drain. Something on the inside of the car is draining the battery but I'm not seeing it through the multimeter.
 

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Doesnt matter if the amp meter is put in the neg or pos cable to the batt. Current draw thru neg = current draw thru pos. It is a series circuit.
 

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Sounds like a bad battery to me. I had a battery that would die every night. I would hook it up to a maintainer and it would charge up completely (supposedly), but then would be weak or not start despite reading a good 12.5v.

Then one day it just stopped being able to start the car at all and I had to replace it.

A load test or one of those midtronics tests will be the only thing that'll tell you for sure.
 

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You might be looking in the wrong places. The draw might not be killing the battery but a lack of proper charge whether its through the alternator or a bad cable possibly.

I have had alternators test good and the bearings are still bad in them and they produce a weak charge as a result.

Just trying to give you some ideas and get you thinking so you can fix it. Good luck
 

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Discussion Starter · #8 · (Edited)
I'll take the car in and have the battery load tested. Given the last battery still tested good but weak (to many discharges + recharges) and was replaced a week ago I'm not convinced but I need to check it for sure. I'm more inclined to believe it is the alternator. It has always tested good but the problem persists. The car has only 77k on it and is garage kept. The cables are perfect, have no corrosion and are all tight. After I replaced the battery a week ago I kept the car for 4 days. I let it set for 3 days and went out and it started and ran fine. The next day I drove the car all day and and the took it back to the inlaws and parked it in the garage. The next day my mother inlaw drove it to the store and back. The day after that the battery was dead and the car wouldn't start. The car sat another 2 days before I could get over there. When I got the the battery was at 8.83v. I pulled the positive cable and checked the draw for the 10th time. 120ma for 40 min and 20ma after that. I put the charger on it with instructions as to when to take it off. That was yesterday. I'm thinking it has to be the alternator or something intermittent that I haven't caught yet with the multimeter. Please keep the ideas coming, I appreciate the help.
 

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Charge the battery over night and then do a load test on it. Also, pull the drive belt from the alternator and spin it by hand, if it sounds anything but smooth it should be repaired or replaced. I've had plenty of alternators that have bench tested good but were bad when put into service. If the key off draw on your battery is within normal, your problem lies with your battery not being charged properly or with it not being able to hold a full charge.
 

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At home alt test: Start car. measure volts @ batt. Should be around 14.2 V. A bit higher @ colder temps. Turn on everything (blower on high, rear defrost, lights, etc). Voltage should only drop .2 to .3 volts.
 

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the weird part of it is that you got a reading of 8.83. If it were an alternator problem, you would be having starting and running problems long before the battery would drain down to that point. For it to get that low, I would think there must be either something draining the battery while it's off. 11.9V is considered 0% charged, so 8.83V is way below that.

I've had a bad alternator before, and what happened to me on the highway was all of a sudden everything started going dim, the engine started sounding strange, the speedometer started going all over the place, the car started bucking, and eventually it stalled out completely unable to restart. The battery had discharged without the alternator.

But once off, there should be no further drain down to 8.83, that's well below the starting and running threshold as far as I know.

Ruling out the new battery would be the first step. I've had a brand new battery go bad instantly one day after only a few weeks of owning it, so it's definitely possible.

Oh and also, it could be your alternator diodes are shot and are destroying your batteries with AC current. Make sure to have it tested with a machine that can test for that too. (or if you have a true RMS multimeter you can test it yourself on the AC setting, regular meters will give false readings)
 

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Discussion Starter · #12 ·
Thanks for all of the replies. I had the battery and alternator tested the day before I changed out the battry. Both tested good but the battery tested good but weak. I asked about the diodes and the autozone guy that tested it said the diodes tested good. I know what your saying about the draw. There has to be a draw on the battery for it to get that low while not in use. Neither myself or inlaws have had any indication of low battery or non charging alternator while driving. Again, every time it has been tested the measured draw has been 20ma. I have not tested the alternator charge at the battery with all accessories running. I will do that next and then take it to autozone to have the battery load tested.
 

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At home alt test: Start car. measure volts @ batt. Should be around 14.2 V. A bit higher @ colder temps. Turn on everything (blower on high, rear defrost, lights, etc). Voltage should only drop .2 to .3 volts.
Do-it-yourself load test. Works every time to show up a bad voltage regulator, which is integral to your alternator.
 

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Discussion Starter · #15 ·
No lights were left on. I opened the door, popped the hood, shut the door unhooked the + cable and hooked up the multimeter. 120ma and 40 minutes later 20ma. Something is draining the battery while sitting but I can't see it on the multimeter. I will load test the battery today. I know the Alternator tested good but bad diodes?
 

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Not to redirect info from KSwagon

I myself have issues with a dead battery from sitting over night

I have:
2.0 amps draw with the doors open
800 milli with the door closed
200 miili after the system times out in 30 seconds
40 milli if I unplug the battery saver fuse or the gen/pats/rats fuse

Currently driving with the rats fuse out so I a have wipers :)
I noticed my front door locks are suddenly not wanting to lock, can they draw if they are half cycled?

as for KSwagon....no draw....should be no problems....that is a tough one...will help if i stumble on something!
 

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Was just looking at mine

Why cant you just disconnect the Alt lead from the Mega Fuse at the relay box in front of the engine

Shouldn't that eliminate any draw through the Alt?

Does it go dead every night...Disconnect it and try it, if it cures it then do the Alt

Funny...no draw...no dead battery....plain logic right?

as for mine:

I checked and i stand corrected, as I have the 10 amp Battery Saver Fuse out... the meter rests at 21 millis

With the fuse back in it rests at 122 millis

I tried the Alt wire removal and it didn't affect the draw at all
 

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Since this seems to be a tough one, I'll jump in with my O-Pinion. I agree with JeffK that 20 MA is normal draw after module sleepytime. I suspect a door/hood/tailgate switch is opening cold. Do your relatives leave it unlocked in the garage? If so then the alarm won't sound if the door/hood switch opens, but it will light up a bulb and drain the battery. The Taurus kills its lights after a period to prevent this, but if a door switch keeps randomly opening all bets are off. Have your relatives lock the doors (alarm on) from now on and if the alarm goes off at night then the event can be read with the right scantool to tell you which switch opened. in the meantime do a visual inspection of the hood and gate switch contact surfaces and check the switches for corrosion.

Don't forget to run back through the basics: pull the battery from the car and put it on a 2 amp trickle charge overnight, making sure it's fully charged. Then load test it with either your own equipment or at Advance/NAPA etc. If it passes, reinstall it and load test the alternator. Clean the alternator connections for peace of mind if you want. Always remember that any tests done on a battery with less than a full charge (12.5/12.6 V) are a waste of time.
 

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Discussion Starter · #19 ·
Eric2cycle you have to leave the multimeter connected for at least 40 minutes to see if the GEM is working properly.

After recharging the battery this last time my mother inlaw pulled the car out of the garage and left it in the drive way. Nothing was touched after or changed from when the battery drained. That was on Sunday, I load tested the battery on Tuesday and the car started just fine. The test had a charge of 14.69 with nothing on. Under a load was 14.63.

I will have them start locking the car at all times when not in use. Can anyone tell me if the radio or antenna are on the battery saver circuit? Is there anything else inside the car that is not part of the battery saver circuit?.
 

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I don't know about the radio or antenna being on the battery saver. I tend to doubt the antenna would be at least. However, I would think something mechanical like that would be causing a constant draw that you would be detecting.

Where you're aren't detecting anything, maybe it's something more like a computer module or something.

What I'm thinking is, to test the draw, you've needed to disconnect the battery and connect your meter through it (unless you're using one of those clamp on meters, in which case this makes no sense). By doing this, you're also resetting all the computer modules, which may be causing them to act normal for a time. But then after a while, they may be flaking out and causing a draw. Then when you go back to test it again, you're again inadvertently resetting them.

Don't know if that's a stretch, but it's just another thing to consider.
 
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