Battery light

[mymark93]

So, everyone knows that little battery light that is by your gauges. Well, mine seems to have a problem of not going away. The light came on about 4 weeks ago and I ended up being stranded and had to buy an altenator for my mark. The battery is not old enough to really be giving me any problems, and the light actually goes away when I give it some gas. Not sure what is going on here.

 

[unity]

Ya, alternator more than likely was the original problem. But driving for a month on that may have toasted the battery. I have read many "reports" that both the alternator and battery needed replacing at the same time. Keep an eye on the battery or get it tested for free. I am betting it needs replacement.

You may also want to replace the "pug tail" on the harness going to the alternator, again something i have read as a recommendation.

 

[Right on the Mark]

Did you buy a FORD alt or a reman from one of the parts store chains? If from parts store its most likely faulty. They are super known in the mk8 world of being real bad in the rebuilding. Just hook up a volt meter to your battery while motor is running and check volts. Should read 14.2V at idle roughtly. Frank

 

[Frogman]

What if it's idling smoothly? :lol:

 

[mymark93]

what would happen if I was just to buy a bigger battery, those altenators are expensive

 

[Right on the Mark]

If the alt is faulty just return it for another one. First thing you should do is check volts. If its toast its toast,no putting in a bigger battery will help. The only job of the alt is to "refill" the battery with power so if its not working right it won't charge any size battery properly.

 

[billcu]

Please could you do me (and maybe someone else here) a favor?

Could you measure the voltage at the battery when the car is idling and the light is on?

I've never even seen the light come on and I'm curious what the voltage is when it comes on. I've had to replace both of my batteries and never saw a light. The batteries were both over 5 years old and died suddenly (with no light) but the alternators were/are fine.

This should tell you if you've got a bad alternator too.

For the battery, you should charge it fully and then put a load tester on it to see if it's OK.

 

[mymark93]

Well, another way to tell if it is a bad altenator is to start the car and then disconnect the battery if the car dies the altenator is bad.

 

[billcu]

Well, another way to tell if it is a bad altenator is to start the car and then disconnect the battery if the car dies the altenator is bad.

I wouldn't recomend that. It's easier to measure the voltage anyway.

 

[Redwingvksm]

...I've never even seen the light come on and I'm curious what the voltage is when it comes on. I've had to replace both of my batteries and never saw a light. The batteries were both over 5 years old and died suddenly (with no light) but the alternators were/are fine...

5 years is pretty typical for a battery. Sulfated plates are one thing that comes to mind. They are just a chemical reaction that is constantly going inside it and it needs to be 'freshened up' from time to time. Signs are that it'll not hold a charge, die overnight, etc.

The batt light only comes on when the voltage/amperage is below a certian level. If you went Re-Man it is VERY common on ALL cars to get a bad one. It kinda amazes me how many I have to return for it being bad You should be able to exchange it - unless you pulled one from a junk-yard. (You'd be suprised how many people have done that here )

 

[Redwingvksm]

Well, another way to tell if it is a bad altenator is to start the car and then disconnect the battery if the car dies the altenator is bad.

And not to mention all the computers you can fry with that voltage spike that happens when you remove the cable. Comon now man.

 

[gangstaMK8]

definetly alternator!! No if's And's or but's about it. mine just did that :q:q:q:q to me a week ago...Bramd new battery my alternator drained on me. I had put a reman in about 1 yr ago and it already died...time for a rebuild.