Alternator or Battery Problem

[jschrauwen]

Background;
Late last Fall / early winter after driving through heavy rain I observed the "Charge" light coming on dimly. I switched off the foggies, radio and heater fan - a normal habit when a situation like this occurs. From then on it was either hit or miss if the Charge light would come on. When it did, it would be near full brightness at idle and would taper off til almost completely out dependant on how high the rpms were. At highway speeds it would be nearly out. If I were to stop for a bit and then start it up again, and I don't see the charge light immediately, then it normally remains off for the complete trip. This was an intermittent thing until just recently when last weekend when I went to take the car out the battery was insufficiently strong enough to start the car. A jump with booster cables got it started and it ran the entire day without a charge light indication. Today, the car started fine but the charge light came on on start up. It dimmed until nearly completely out for the first part of a short trip and would get brighter when at idle again. After stopping the engine and restarting the car the charge light did not show at all and remained so for the first part of the trip. On the return leg the charge light came on again on initial start-up and went to the dimmed position for the duration of the highway portion. During that highway drive other accessory items started to show negative effects, ie radio cut out when turn signal applied, when at stop lights speedo and tach indications fell to zero. Something is quite wrong. When I got home and shut off the car it would not restart - no juice in battery. Voltage check indicated just over 10volts.
Since operating at highway speeds it didn't affect performance that was recognizable except for the accessories. I'm thinking it may be a dead cell in the battery but I'm not %100. I thought possibly it would be the alternator, but then if it was wouldn't that affect performance at idle or highway speeds. Idle still remained rock solid at 700 rpm. Battery is currently on charge right now to see if it will take and hold a charge. Is there something else I should direct my attention to. Ground cables perhaps, alt belt??? I'm going to try and do a check of output voltage at the battery terminals tonight or tomorrow. Any other suggestions?

[Nd4SpdSe]

Well, there is a recall on our alternators...you could look into that. I am.
Last year a few weeks before ImportFest, after some wheelhop racing my friend Cobalt, I got the charge light, but would disapear around 3000rpms (so on the highway I had no problems), so i drove like that for almost a week, keeping my gears low and revs up, until on a drive back to Niagara it decided to fix itself. So i drove around with it working for about 2 weeks until it decided to act up on the drive to ImportFest, but again, on the drive back to Niagara the next day, it fixed itself. Now it's been working fine, but i can hear the alternator, it doesn't sound healthy, but it doesn't complain. I'm going to ask to Mazda about the recall on my car when i go back this week. If they say no, than I'm going to go with the Millenia 110amp alternator swap, but if i can get it replaced for free, than why not.

Did you try a voltage check while the car is runing (especially with the charge light on)? The alternator should be putting out ~14v. Personally, if it was a dead cell in the battery, I dont think it can intermitently be dead, either is it or it isn't. From my experience, only alternators can act flaky. But it could also be related to the wire runing from the alternator to the battery, issues like corrosion (your car is by far young) could cause intermitent issues. Personally I would look at the alternator back, thinking the battery as a last resort, although it is the easiest to test.

[Aston Wards]

My guess would be the alternator is on the way out....., the extra load of the fan at idle, the fogs, wipers, heater in the rain....

what is the voltage across the terminals while the car is running? if the alternator is up to scratch it should be over 13v........, that's about the full extent of my electrical knowledge!




D'oh....., looks like i type too s.l.o.w.l.y!

[Grants]

Sounds like the alternator alright. Or the wiring coming from it (less likely).

It sounds like the battery is going flat as it discharges to provide power as the alternator isn't up to it.

When the charge light is on, pull the battery terminal off and see if it shuts down.

[Tunes67]

And when you replace the alternator.. do yourself a favor and get a Millenia Alternator and wiring plug. These alternators put out 110 amps compared to the stock GS alt of 90 amps. The mounting brackets are supposed to be the same. However.. the plug that goes into the alternator is shaped differently. Though it is still the same number of wires. Just cut and splice and plug it in for a nifty power upgrade for about the same cost.

Tunes67

[precidian]

I had my alternator rebuilt when I had problems with it. After rebuild, the alternator was rated at 125amps.

[papadeez15]

i had teh exact same problem as u
it was my alternator