If the battery still does not charge after checking the voltage regulator and carbon brushes, it is advisable to have your alternator checked on a test bench to find out what is wrong.
If the result is negative, you have the choice between overhaul or replacement. When overhauling, you keep the original, but in many cases this is expensive. Replacing it with a new factory copy is often cheaper and you are guaranteed a 100% new part.
If you have a choice between A-quality and B-quality, A-quality is the same quality as the original while B-quality is much cheaper, but don't expect miracles. With quality B, you will have to accept that life and reliability are much less important. With B-quality, you can't make a warranty claim, so make a thoughtful choice.
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