Battery charge light on intemittant

[vinny121]

battery light is on intermittantly

Hi, My Yaris with 133K miles has an intermittent issue with the battery warning light.
It seems to happen after a rainstorm and/or after a cold start. My battery keeps a steady charge but when the battery light is on, it affects engine performance slightly.
I notice the battery light mostly during idle. I have read posts of the voltage regulator and the corroded screw connections.

I searched through the car-parts.com website for used parts but did not find local results. Also I contacted Toyota and they want $620 for a new alternator and this doesn't include labor to install. My local repair shop says that it costs $384 for part and labor to install an aftermarket alternator and they won't take apart the original one.

I went through a similar behavior when the rear abs sensors had to be cleaned and never had an issue after I used electronic sensor cleaner spray on them. There is no way to fix this without taking the alternator off the yaris and taking it apart? I actually broke a ratchet socket attempting to take the top bolt off and was unsuccessful. Your help is appreciated. Thanks