Since getting my 2006 RX-8 at a used car dealer a couple months ago, I've had some slight issues with the biggest one being that the voltage regulator in my alternator was bad. I just got that fixed about a month ago by replacing the alternator with a brand new one and haven't had any of the problems I used to.

Just earlier today the battery light on my dash came on. At first intermittently but by the end of the day (maybe an hour total drivetime) the light just stayed on. I've looked at the battery itself, and while one of the terminals looks a little dirty with grease, I went to AutoZone earlier today and they said the battery connections, starter, and alternator were just fine. I checked my drive belt and battery terminals and both are tight and in their places.

I have no idea what the issue could be and I really hope someone could help me figure out what I could do next to make sure that battery light (or lack of charging battery light) goes off.

Thank you all

- Ryan

 

Where did you get the alternator?

If you got it from AutoZone, I have read on other forums that AutoZone alternators are not the greatest.

 

My mechanic got a new one and replaced it, so I'm not entirely sure where he got it from

 

There is a big difference between brand new (and even between brands) and new remanufactured, a lot of time the remanufactured ones just are old cores that get QCed and cleaned (maybe new brushes and bearings) and put in a box and shipped out. I've had plenty of remanufactured ones die after only months of use, good news is it should be under warranty.

 

I checked with the mechanic and it is a completely new alternator. My battery light didn't turn on today until I accelerated pretty hard and shot the rpm up to between 3 and 4k. The car has been running just fine so I can't think of what else I could check without taking it to a mechanic. I've checked the battery itself and it seems to be giving the power it needs to. This problem didn't pop up until early yesterday, could it have something to do with the heat? It's been above 110 F pretty regularly here this week and my car spends at least 7 hours a day in the sun

 

If you have a multimeter, you can test the alternator output voltage witht he engine running and see where it is at idle. If not, I would remove the alternator and have it tested. It may be functioning but may still have a bad regulator that's either overcharging or undercharging, causing the light to illuminate. The battery light usually will not illuminate for much else other than a charging condition. A bad battery will likely not cause the light. I would have the alternator tested. They are easy to remove and you will learn something in the process. But do disconnect your battery before messing with the alternator.

 

If the battery light is more prominent under higher RPM maybe the belt isn't tensioned properly and slipping.

 

^^This is an excellent point. Belt tension is very critical. Also, check the condition of the belt to make sure its not cracked or glazed. If its in poor condition make sure you replace it and tension it properly.