Kia optima flickering headlights

I have a 2002 Kia Optima. The headlights have been flickering as well as every light inside the car. When they’re doing this, if I press on the brakes, everything fades out. Such as the radio, headlights get very dim, air conditioner fades out. The car almost comes to the point of stalling. I’ve had the alternator replaced but the problem continued. I have asked several mechanics but they are baffled. HELP!!!

Has anyone cleaned the battery connections? You need to find a good independent mechanic who can check all the battery connections and make sure they are clean and tight. There are just too many possibilities to name them all. I would also have the mechanic install a ground between the engine and frame.

Good mechanics are so hard to find! Actually, yes I have cleaned the connections to the battery. I’ll try the ground next. Thanks so much for your suggestions!

When this is happening, ask your mechanic to measure the voltage at the battery, both on the battery, and on the connectors which connect to the battery. I expect you have either a bad battery, alternator, power connections, or ground connections. A faulty ignition switch, main relay, fuse, or wire splice is also possible.

It’s alway better to tell the mechanic what to fox rather than tell him what to do to fix it. Had you asked to have the problem diagnosed rather than just to replace the alternator, you probably would have saved yourself the cost of an alternator.

Since you’ve already had the alternator replaced, I’m betting on the battery. Have the entire charging system and battery tested and all teh connections checked.

I’ll bet my morning muffin that the battery is original. Do I owe you a muffin?

Flickering lights usually means there are some bad diodes inside the alternator. Assuming the replacement alternator is okay there might be a bad connection between the alternator and the positive battery post which would keep the battery from getting a full charge. There should be less than .3 volts across those points while there is a good load on the system if that connection is okay. I assume the battery has already been checked for a problem but if not it needs to be. If those things are okay then the wiring from the battery to the panel under the hood needs to be checked doing a voltage drop test just like the alternator to the battery. The battery to chassis ground needs to be checked also.

Thanks to everyone for all your suggestions! This is great! It’s more info that I’ve received from mechanics, friends, etc. And to mountain bike, I’ll take blueberry please. Battery not original…