Battery light turns on above 6k every time since changing alternator
 

2013 FRS, 232k km (144k miles) I had my alternator fail so we changed the alternator and the battery, ever since whenever I go above 6k rpm, the check battery light goes on. Mechanic says it's charging fine, and the current is passing fine, even though the light comes on.
My motor blew up so I had a replacement engine installed, hoped the rewiring would help but no luck, it still lights up above 6k every time.
Sometimes when I start the car the check battery light is barely on, it's visible if you look hard. It never did that before. Sometimes it's completely off though (light still turns on above 6k)
Any help is appreciated.

Put a volt meter on it. See what the voltage is doing above 6k. My guess is the regulator is not controlling the voltage correct.

Generally speaking when”it was not doing it until I replaced X” X is the problem.

I agree, the problem is that my local mechanic doesn't have a bunch of FRS alternators in stock


I'd need to buy one on my own dime, and IF it fixes the problem then I would be credited the broken old one. If it doesn't then I'm stuck with 2 alternators. I just wanted to see if anyone else ever had a similar issue.

Multimeters are inexpensive and essential. If your local mechanic can't easily verify, find another that isn't lazy, stupid, or both.

Go buy one of these.

https://www.amazon.com/Palumma-Charg...zcF9hdGY&psc=1

See what it tells you at different RPM’s. You car voltage should be steady. My guess is 13.8v to 14.2V. If it get high or low at high RPM’s and the light comes on tell you mechanic he sold you a shitty alternator. Get him to replace it and find a new mechanic.

typically charging voltage is 13.2-14.4v

if the battery light is coming on, it would be a preliminary indicator that the voltage is falling closer to 12v.

Ordered! Thanks guys