Battery Charging Light on after 2nd Gear - 2003 Mazda Protege

Basic backstory:

On a hot day I was running the AC. About a quarter mile from home the battery charging light came on and the car lost most power. I was able to nurse it home, and later it started okay. I drove it over to autozone and had them test the battery and the alternator, battery tested low charge, but okay, and the alternator tested with a low output. At this point I noticed that the belts were frayed and bought new belts. (These had 130,000 miles on them)

Belts were replaced and everything seemed fine for a day. Next day, while trying to pick my wife up from the airport, light came on halfway between home and the airport. Had to stop by at my relative / mechanic’s house to charge the battery so I could limp home. At this point, it seems like anytime I take the car above 2nd gear, the light comes on and power drops. If I leave the battery hooked up overnight, it’s drained by morning.

I took the car back to autozone after an overnight charge and both the alternator and battery now test fine.

So, what’s left to test? I don’t know what other components of the charging circuit are involved, so I’m stumped.

There are no other components in the charging circuit. You said the alternator tested with a low output. Sounds to me like the alternator is not charging sufficiently. I think I’d replace the alternator if this were my car. At 130K miles it wouldn’t be unusual for the alternator to be failing.

You didn’t say how old the battery is. You may need a new battery, too. Did they do a “load test” on the battery. That’s the real test for a battery.

Mcparadise has given you very good advice. Like him, I also would doubt the ability of your alternator to keep the battery properly charged.

What are your responses to his questions?

Sorry, it would have been relevant to mention that the alternator currently in the car is less than two years old and has 23k miles on it. The battery is a touch older at around 2.5 years. I’m honestly not sure what test Autozone would have done on the battery. Is a load test something they normally would do, or would a specialty shop be needed?

Does it make a difference that the alternator tested normally the second time around? Also, charging light went off today when the AC was turned on, but came on within seconds of the AC being turned off.

Yes, that would have been, and is, relevant information.

It’s like pulling teeth.

It’s not out of the realm of possibility to have a replacement alternator fail within two years and 23K miles. These things happen now and then.

The alternator tested bad. Have it tested again, and again. See what comes up.

Some alternator troubles happen at higher RPMs. I suspect this is what happening on yours. I suggest you swap the alternator out. You may also have an excessive current drain on the battery while the car is parked. Have the battery current draw checked to see if there is a problem in that area.

Yeah, I was tinkering last night and tightened the belts a hair, the displacement felt about a half inch, which according to the manual is too loose. After I tightened the belts, I could start the car, the battery light would come on at idle, go off at higher RPMs, come back on at idle, and go off when I turned on the fan. Granted, this was all in the garage, so I’m going to drive it around today and see how it behaves on the way to Autozone. I’m going to have them pull the code and test the alternator and battery again, now that I haven’t had the battery on the charger. I’m going to see if they’ll be able to keep the tester on there when I can actually get the battery charging light to come on, and then see what it says when I turn on the fan.

I can take the alternator out and get it bench tested, but that will have to wait until I can get it to a better equipped garage than mine.

Sorry to keep picking at questions, money is just tight now, so I was just trying to avoid buying a part and then getting it installed and finding something else wrong.

Since I’m going to end up buying a new alternator, has a remanufactured Bosch and a New NSC alternator for around the same price point. Any feedback on the best way to go? Both are cheaper than the part at Autozone, which I’m leary of, considering it lasted such a short time.

So what you’re saying is that the last alternator you purchased-the one with the 23k miles on it was previously purchased at Autozone? Don’t they have a lifetime warranty on it. That would seem the cheapest way to pursue, if money is a factor at present.

They do, but it’s dependent on either finding the receipt or the data in their system. My regular mechanic, also a relative, purchased the part and I just paid him direct. Unfortuntely, we’re not finding the part under his info or mine in their computer. This is ultimately my fault for not collecting the receipt from him at the time of service. If this were a regular business I would press them on the warranty, but being family, I might end up having to eat the crap sandwich and buy the part.

Any suggestions regarding the brands I mentioned or others? Looks like I can get a 10% coupon for parts direct, and the two cheapest alternators are the remanu’d Bosch and the new NCS. I’ve seen very few reviews of the NCS parts, but they were all favorable.