the battery light is on?

Here's a link to an article about testing the charging system, but it's important to understand any testing has to be done while the warning light is on. Everything is working properly when the warning light is off it could be the computer going bad and not monitoring the system correctly.

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

lets run the guides as well

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

This article explains how to use a digital voltmeter:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Please run down these guides and report back.

About a month ago, I noticed that my battery light on my dashboard came on. Within a few days, I felt the car slowly losing power and eventually once even shut off. I took it to a local mechanic and had it tested, for them to say that I had no issues, but my battery was testing on the lower side so they recommend that I replace it, which I did. However, a few days later my car started doing the same thing (losing power, battery light still on), so I returned to the mechanic where they ended up having to replace my alternator as well. Now, a few weeks later, my battery light still comes on and I still feel as if my car isn't using as much power as it should, especially when I'm idle or at a stop. The car even sputters sometimes and has an intention vibration whenever I'm sitting still (in park or in drive). PLEASE HELP.

It sounds like the alternator was your problem the entire time and the rebuilt one they installed has gone bad, I would replace it with a Motorcraft unit here is a guide to walk you through the steps and instructions for your can in the diagrams below.

https://www.2carpros.com/articles/how-to-replace-an-alternator


Check out the diagrams (Below). Please let us know what happens.

Thank you for this post I had this problem had to get a motorcraft unit from Amazon for $143.00 fixed it! I love this site.

I have a diesel engine.

Just after Christmas 2016 my car would not start, i suspected a flat battery. I called my breakdown guys who came out and jumped the battery and left the car running. I took the car for a little drive and took it to halfords who tested the battery and said to take the car for a long drive to make sure battery gets recharged. As i did this the battery light came on, the emergency light came on for a short while and disappeared, the power steering malfunction message also displayed but had no problem with power steering.

I took car back to Halfords who recommended changing the battery which i did. However the battery light remained. I took the car to a Ford dealership for a diagnostic, they said the battery had a faulty cell and that it would need replacing. I took the car back to Halfords who checked the battery and said that there was nothing wrong with it, however, replaced the battery for my piece of mind. When i restarted the car the battery light was still showing.

I was told by the Halfords man that i may have an issue with the alternator or that the computer system may need resetting. I am not sure what the issue is. I hope you can give me some advice.

Do you have access to a multi meter? My suspicion is like yours in that you have an alternator related problem.

If you can get a meter, connect it across the battery terminals with the engine off and note the reading. 12.4 volts to 12.6 volts would be good. Now start the engine. You should see the meter go up to between 13.5 and 14 volts as it charges the battery. If you see no change the alternator is not charging.

Thanks for your reply.

I do not have access to a multi meter, however, I will get this checked out.

If the voltage goes up like you have stated, that would indicate that the alternator is charging the battery. If the reading shows this and i still have the battery light showing, what could that be a result of.

I would also like to add that when driving, i have noticed the light switch off for a short while and then turn back on a again.

If it is charging properly with the light on, it is likely a bad wire or connection at the alternator. I think under a proper test of output and ripple voltage that the alternator will likely test bad, but I have been wrong before.

Okay, thanks for your help. I will have to take it into a garage to get it checked out.

Hey,

Did you ever get the problem fixed?

Best, Ken

Yes i did thank you. I apologise for the late reply. The issue was a faulty alternator. Its now been replaced and all is good.

Thanks for the feedback, please use 2CarPros anytime we are here to help.

Ford Focus 05, milage 32000, 2.0 engine.

I changed the battery in my Focus. Now the battery light on the dash stays on even when the car is off. I checked all the fuses. What else could be causing this? Also, how would I disconnect the little flashing LED that the dealer installed to look like an alarm system?

We had the same problem in ours, replaced battery and alternator, still stayed lit up. Hubby checked fuses in fuse box in engine, there was a burnt out fuse there, replaced it and light went off.
Hope that solves it.

Good luck!!

My battery light comes on occasionally for a few seconds when I run my air conditioner. It doesn't happen when the a/c isn't running.

Have the alternator load tested with a VAT machine-Sounds like its not compensating for the additional load from the AC

That makes sense. Thank you very much.

My battery light keeps coming on, I have checked belts, battery and all connections. Next step is my alternator. How can I check it without having to go completly through the process of removing it and then finding out it is ok?

Generator On-Vehicle Tests - Load Test Switch the tester to the ammeter function. Connect the positive and negative leads of the tester to the corresponding battery terminals. Connect the current probe to the generator B+ output terminal, circuit 30-BA6 (RD). With the engine running at approximately 2,000 RPM, adjust the tester load bank to determine the output of the generator. Generator output should be greater than the graph shown below in order to pass this test. If the test is passed, refer back to the pinpoint test or GO to SYMPTOM CHART. If the test is not passed, install a new generator. For additional information, refer to GENERATOR AND REGULATOR . Fig. 11: Generator Output Graph Courtesy of FORD MOTOR CO.

Generator On-Vehicle Tests - No Load Test Switch the tester to the voltmeter function. Connect the voltmeter positive lead to the generator B+ terminal, circuit 30-BA6 (RD) and the negative lead to ground. Turn all electrical accessories off. With the engine running at approximately 2,000 RPM, check the generator output voltage. The voltage should be between 13.0 and 15.0 volts in order to pass this test. If the test is passed, refer back to the pinpoint test or GO to SYMPTOM CHART. If the test is not passed, install a new generator.

Battery light came on and I cleaned connections. Started car light came on in seconds so I checked battery voltage it was 12.4. Started car and then checked voltage it was 12.5 and then dropped. I charged battery to 12.8 and then started car checked voltage 4 times while running voltage dropped each time to 12.3. wiring seems tight and ground seems good. Do you think I should change alt.

It does sound like an alternator problem indeed. Have it checked at your local auto part store.