Battery Light
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Post Fiend
Joined: Nov 2001
Posts: 14,947
Likes: 6
From: Topsfield, MA
Battery Light
What's it really mean when the battery light comes on? (02 focus)...
I assume it's the same as other vehicles so I put it here in the gen. auto. and isn't it the regulator for the alternator?
The light comes on and off occasionally.
I assume it's the same as other vehicles so I put it here in the gen. auto. and isn't it the regulator for the alternator?
The light comes on and off occasionally.
Logistics Pro
Joined: Mar 2004
Posts: 4,221
Likes: 3
I think in general it'll indicate some problem with the charging system, be it alternator, battery, connection at terminals (corrosion), etc.
If you start to notice it comes on at lower rpms, but goes away at higher rpms, it's likely an alternator.
There's a simple test with a voltmeter to see how the alternator's doing that I can share, if interested.
If you start to notice it comes on at lower rpms, but goes away at higher rpms, it's likely an alternator.
There's a simple test with a voltmeter to see how the alternator's doing that I can share, if interested.
Post Fiend
Joined: Mar 2003
Posts: 14,413
Likes: 3
From: Sarnia, Ontario, CANADA!
Why are you asking that question Justin? Is there something wrong with MY 2002 Focus that I don't know about? 
It is probably the alternator going out. It will eventually stay on all the time. But, you can check the cables and things first. Have fun if you need to change the alternator!
-Matt
It is probably the alternator going out. It will eventually stay on all the time. But, you can check the cables and things first. Have fun if you need to change the alternator!
-Matt
Logistics Pro
Joined: Mar 2004
Posts: 4,221
Likes: 3
Here's how you can test it to see if the alternator is charging properly:
test the battery voltage with the engine off - should be around 12 volts or so.
then, start the engine, retest voltage - whatever the battery voltage was w/ the engine off, the voltage should now be 1.5-2 volts or so higher, indicating that the alternator is charging. If the voltage does not increase, it's likely an alternator problem.
Autozone or the like can also use their testing system to put a load on it and test it, but this is a very quick test you can do at home.
test the battery voltage with the engine off - should be around 12 volts or so.
then, start the engine, retest voltage - whatever the battery voltage was w/ the engine off, the voltage should now be 1.5-2 volts or so higher, indicating that the alternator is charging. If the voltage does not increase, it's likely an alternator problem.
Autozone or the like can also use their testing system to put a load on it and test it, but this is a very quick test you can do at home.
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Senior User
Joined: Mar 2006
Posts: 313
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as far as i know all it dose is check the alternater, you can take out the battery and the light wont come on unless there is a alternater problem
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