Alternator won't charge battery?

Tiny
HAWKJTEYE691
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  • 2000 FORD CONTOUR
  • 4 CYL
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  • 154,000 MILES
I changed the alternator 2 x's in the past year, changed the battery twice. Changed the battery terminals, gave it a tune up, and i'm still having the same problem = The car needs a Jump Start. I Jump Start the car in the morning, drive to destination, the car sits for 8 hours, It starts fine, drive home. The car sits overnight and needs a Jump start again. Sometimes the battery light comes on, blinks a few times and goes off while driving. What is going on!
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Monday, August 31st, 2009 AT 12:48 AM

22 Replies

Tiny
RASMATAZ
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Sounds like you have a short somewhere within the electrical systen eating up the battery overnite. Do the battery drain test below.


https://www.2carpros.com/forum/automotive_pictures/12900_parastic_draw_1_127.jpg



This guide can help test the alternator.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

Please run down this guide and report back.
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Monday, August 31st, 2009 AT 5:34 AM
Tiny
GCASTINO
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  • 1999 FORD CONTOUR
  • 6 CYL
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I put a new Alternator on and battery is good, but it still goes dead after 5 min. I checked the back of the Alternator and it puts out around 13 or 14 volts, so I know the Alternator works. I charged the battery with a battery charger and it hold a full charge, but when you start the car it takes all the juice out of the battery and the car goes dead. What can be wrong? Also someone told me about a maga fuse on the back of the motor that can be bad. I just don't know where it is or what it looks like.
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
RASMATAZ
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Do a voltage drop on the battery cables/get the battery load tested to check its condition then comeback
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
GCASTINO
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Sorry but how do you do a voltage drop on the battery cables. Please tell me what to do.
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
RASMATAZ
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VOLTAGE DROP TEST

A voltage drop test is the only effective way to find excessive resistance in high amperage circuits. It's a quick and easy test that doesn't require any disassembly and will quickly show you whether or not you've got a good connection or a bad one.

To do a voltage drop test, you create a load in the circuit that's being tested. Then you use a digital volt meter (DVM) to measure the voltage drop across the live connection while it is under the load. Voltage always follows the path of least resistance, so if the circuit or connection being tested has too much resistance some of the voltage will flow through the DVM and create a voltage reading.


https://www.2carpros.com/forum/automotive_pictures/12900_voltage_drop_2.jpg



If a connection is good, you should find little or no voltage drop and see less than 0.4 volts for most connections, and ideally less than 0.1 volts. But if you find more than a few tenths of a voltage drop across a connection, it indicates excessive resistance and a need for cleaning or repair.

CHECKING THE STARTER CIRCUIT

To check the starter circuit for excessive resistance, you need to measure the voltage drop at the battery, battery cable connections and starter while the engine is being cranked.

The first check is "available battery voltage." For the starter to crank at normal speed, the battery must be at least 75% charged (12.4 volts or higher). Low battery voltage can not only affect the starter but every other electrical system in the vehicle.

A. Set your DVM to the 20 volt scale, then connect meter positive (+) lead to battery positive (+) post (not the clamp or cable), and the meter negative (-) lead to battery negative (-) post.

B. Disable the engine so it will not start when it is cranked. (Ground the ignition coil wire, or disable the ignition circuit or fuel pump relay.) Limit cranking time to 15 seconds or less.

C. While cranking the engine, record the volt reading on the DVM. D. Next, connect your meter positive (+) lead to the battery terminal stud on the starter, and the meter negative (-) lead to the starter housing.

E. While cranking the engine, record the volt reading.

F. Compare the two voltage readings. If both are the same, there are no excessive voltage drops on the positive feed side.

G. If available voltage at the starter is not within one (1) volt of battery voltage, there is excessive voltage drop in the circuit.

The next test is for voltage drop on the positive side of the starter circuit.

A. Make sure the battery is fully charged.

B. Disable ignition.

C. Set DVM on 2 volt scale.

D. Connect meter positive (+) lead to positive (+) battery post, and the meter negative (-) lead to the battery terminal stud on the starter. While cranking the engine, record the voltage reading.

The maximum allowable voltage drop including the solenoid or external relay in the starter circuit should be 0.6 volts or less.

If you find more than a 0.6 volt drop in the starter circuit, you can isolate the bad connection by using the following voltage drop tests.

* Check the positive battery post and cable connection by measuring the voltage drop between the two while cranking the engine. Connect the meter positive lead to the battery post and the meter negative lead to the cable clamp. A good post/cable connection should have zero voltage drop.

* Check the positive battery cable by measuring the voltage drop end to end while cranking the engine. Connect the meter positive lead to the clamp on the positive battery cable, and the meter negative lead to the end of the cable at the starter. Crank the engine and note the voltage reading. A good cable should have a voltage drop of 0.2 volts or less.

* To check the starter solenoid or relay connections, connect the meter positive lead to positive battery terminal on the solenoid or relay, and the meter negative lead to the starter motor terminal. Crank the engine and note the reading. A good connection should have a voltage drop of 0.2 volts or less.

Next, you need to check the negative side of the starter circuit. To check the entire circuit, connect the meter positive lead to a clean spot on the starter motor case and the meter negative lead to the negative battery post. Crank the engine and note the reading. The voltage drop on the negative side should be 0.3 volts or less.

If the voltage drop is too high, set your DVM to the 2 volt scale and start checking each connection on the negative side to find the bad connection or cable. Use the DVM leads to check across each connection while cranking the engine as before.

Check the negative battery post/ground cable connection (should be zero voltage drop).

Check the negative ground cable from the battery to the engine (should be 0.2 volts or less).

Check between the negative battery post and starter housing (should be 0.3 volts or less).

Check between the engine block and starter housing (should be 0.10 volts or less).
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
JOHN99CSVT
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I have a 1999 ford contour SVT with a 2.5 v6. Recentley I was driving and the car was seeming slugish so I reved it up alittle bit. After that the battery light came on so the next day I got it tested at autozone. The alternator was bad so I replaced the alternator and while in the process lof replacing iot I saw the connectors were bad so I bought a new pigtail connector from ford and spliced that in too. After I installed everything I cranked the car up and the alternator was not charging the battery and the lightwas still on. A buddy of mine told me to check the in line fuse so I checked it and replaced it with a new on for the heck of it. The battery tested out good but for some reason the alternator is still not charging. I hooked a multimeter to the alternator with the car running and it was pushing out 12.6 volts where the cable that runs to the battery connects but for some reason is not getting to the battery. Check lines for breaks or corrosion and there is none so far I can see. Really having trouble with this, trying to find anwsers before I spend money at ford for them to look at it. Any suggestions?
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
GUMBOMASTER
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I notice you never got an answer. I have the same trouble with my car and have done mostly the same things. I did not change the 175 amp mega fuse yet, I can't find it at any parts stores. I did check it with an ohmmeter and it is not broken. I did find out that it can become week and will still have continuity. Also the number 5 fuse for the foglamps will give it trouble.

Please, if you did find out the prblem I would sure appreciate to know what you had to do to fix this error. I'm handicapped and have 2 boys and vey limited income. I've been stumped on this one so far.

Thanks a lot if you respond!

BEN
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
2CP-ARCHIVES
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I tested my alternator and it was good was told I needed a new regulator and bought it paid someone to install it they hung it from a neighboring wire grounded it and plugged it in. My car still does not hold a charge and its not my battery because I had it tested too. My question is does the external regulator need to be bolted to the alternator to actually work.
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
HMAC300
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Normally the regulator is inside the alternator, if it was tested as good you shouldn'thave needed anything. If it's not holding a charge either have someone test for adraw or come back to the site here and look under parasitic draw on battery they will show how to test for that.
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
MWK0990
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  • 1996 FORD CONTOUR
  • 134,000 MILES
Car runs but with a 11 to 12 volt reading at battery
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
SATURNTECH9
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Did you have the new alternator tested at the store before leaving the store?Also did you have the old one tested bad out of the car?Also do you have a multimeter to do some testing?
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Friday, September 11th, 2020 AT 1:44 PM (Merged)
Tiny
RASMATAZ
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Have the alternator load tested by Autozone-start here
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
RUSST
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  • 1996 FORD CONTOUR
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Hi I just put a altanater on a ford contour and it is still not charging when you turn the key on the charge lite comes on but after you start it still stays on someone before me had put one on to and still it did not charge what do I need to look for I checked the maxy fuse and it is good
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
JAMES W.
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First, make sure all fuses are good. With a volt meter, engine not running, test voltage at the out put terminal (large wire) of the alternator. If there is 0 voltage, there is a fuseable link out between the alternator and the battery. If you have 12 volts at the alternator, start the engine and test across the positive and negative poles of the battery. You should have 13.5 to 15.0 volts at the battery. If you do, the battery is bad. Let us know what you find.
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
KNEWBI01
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  • 1995 FORD CONTOUR
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I have a 1995 Ford contour. I havent had a problem out of this car, until now. I was driving and pulled into a gas stion, where my car then slowly died down; first the radio went off, then the car cut off, and would not start up again. I got a jump start and drove it about a half mile and it died again. I took the altenator to auto zone to have it checked, the results were good on the altenator, I also replaced the battery. But for some reason the battery is not being charged. What else could it be, if the altenator and the battery are good.
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
RASMATAZ
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But for some reason the battery is not being charged-The job of the alternator to recharge/recondition the battery-test the wiring and find out if the alternator's field generation is being controlled by the computer
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
CONTOUR
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  • 1 POST
  • 1995 FORD CONTOUR
Electrical problem
1995 Ford Contour 6 cyl Front Wheel Drive Automatic 100k miles

Alternator will not charge the battery. Alternator was check in two parts stores and and is working properly, battery is new, mega fuse is good, Connectors are good with no corrosion. There is a 2 volt drop with everything disconected. Fuses, bulb
alternator) The passenger air bag turns on some times. The car runs fine otherwise. WHERE IS THE
PROBLEM?
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
FLEXY5
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It sounds like you may have one of two problems. Either the signal between the alternator and the computer is bad or the computer itself is bad. I believe the voltage regulator is in the PCM itself.
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
MACATAC0
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  • FORD CONTOUR
I have a 1996 ford contour with 97,000 miles. I`m having a problem with the charging system yesterday the battery was shot the guy at the parts store checked the altanator and said it was charging, so I installed a new battery and this morning it was dead again. Before it died it started a series of dings inside the blower quit and it died. Grandpa said he had this problem a year or so he took it to an out of state shop they replaced the battery then discovered a sensor was bad. But he doesn`t remember which one? Does any one have a bit of advice or know of this problem? Thank you
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Friday, September 11th, 2020 AT 1:45 PM (Merged)
Tiny
KEN L
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Lets recheck the altenator, sometime they can work one second and not the next. Thats is were I would start. Let me know please. :D
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Friday, September 11th, 2020 AT 1:45 PM (Merged)

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