NEED HELP!!! Ok so I have a 2002 Honda Civic that started having a flickering battery light last summer (Aug-Sept 2023) while the outside temperatures were still high. I daily the car so on the way to work when it was cool outside I had zero issues. Once my car sat at work in the heat all day I would drive home and about 5mins in my battery light would start to flicker. I had a shop replace the alternator twice and the second time they put a better brand alternator in. The problem did not go away until the temperatures dropped for fall/winter and it’s been fine ever since. A couple days ago when temps got to around +70 degrees my problem returned.. I decided to replace my old battery in hopes it was just a weak battery but today the problem returned. It only does this when it’s hot outside and the car sits in the sun directly at work. I’m at a loss on the issue and I’ve searched the internet from one side to the other hoping to find a similar issue but nobody seems to share my experience with hot temperatures being a leading factor. I’ve done voltage test and getting good readings until the battery light starts to flicker and then it appears my alternator stops charging. What could be overheating and causing my alternator to stop charging only when it’s hot outside???

 

You have a bad connection. Couple of things it could be such as the wire from the ig terminal to the ignition or to the fuse under the dash.
i suspect it is the ignition connection where you put in the key. If the light flickers jiggle the key while running.
The alternator and the battery are not theproblem. The ig terminal has to be live to excite the stator to make the alternator charge.

​​​​​​Check the ohms in the wire from the ig terminal at the alternator boot to the steering column ignition and to the fuse.
or you have a break or bad connection at the ig terminal at the alternator

 

try changing ground straps

 

Also try changing battery terminals and cables