Battery Light going On/Off

[faral]

The battery light on my 1999 Miata has recently started to turn on and off. The first time was after I pulled out of my home's garage (reasonably warm...about 50 degrees in there). It stayed on for most of my 30 minute commute, but then turned off. I checked the belt and the tension seems fine, and the belt condition seems good except for a little bit of wear. That was just over 1 week ago.

Tonight it came on again, after parking it outside in about 40 degree weather for about 3.5 hours. The light turned on almost immedately after starting the engine, and then kept turning on and off. It was pretty random, but it seemed to turn on when I slowed down regardless of if I was in neutral or not. The thermonometer was indicating a temp slightly lower than usual, but I had not driven the car very far yet so I didn't think much of it. Once I hit the freeway, the light turned off and stayed off, even when I went into neutral and slowed to about 25 to cross a toll booth. Tempeature also seemed very steady in the normal area once I was on the freeway.

So, after that very long story...can anyone offer a clue? Is my belt nearing the end of its life? Hopefully its the belt and not the alternator...much cheaper to fix the belt.

Thanks all.

 

[faral]

Oh yeah, and my car is starting just fine. Head lights are not dim.

 

[R2s99zoom]

original factory battery?

if so, it is an 8-year-old battery... usually lead-acid battery's don't last 8 years... (tho miata batterys are gel-cell... my '99's original battery got weak enough for it to be replaced a month ago...)

My car was throwing CEL's because of the deteriorating battery. Started fine (mostly), and no other odd effects.

But a brand new battery stopped my CEL... and it starts a lot easier now... (wasnt really hard to start before, but now its like instant when i twist the key)

The gel-cells used by most miatas seem to be amazing... but the DO wear out after a while

If your '99 still has its stock battery, and its less than say 70 fahrenheit while having probs... try a new battery the factory piece has probably outlived its intended usefulness

 

[MiaTurbo]

The glassmat batteries in the Miadas are awesome. Mine lasted almost 200k miles, and 13 years.

Here is what you need to do: put a volt meter on the battery terminals when it's acting up. It should read about 14.4v. If it doesn't, you're experiancing a charging problem. so the alternator may be culprut.