This one is generic: my daughter’s car apparently needs a new battery. Age of the present battery makes that reasonable (at least four years, came in used car), lights dim with engine off, etc. Is there a quick and reliable home check that her alternator is doing it’s job? In a 98 Honda Accord. All other systems A-OK.
If you have a volt meter, check the alternator output at the battery, engine running. Should see around 13.6 as I recall. You could also take the car to an auto parts store like O’Reilly’s and they can load test it, if you want to take off the car.
I use the volt meter test as the first part of my decision-making process.
Raise engine rpm to 2000. Turn every electrical thing on. Read voltage. It should stay above 13.6 vdc.
Most auto parts stores will check the battery and the charging system for free.