Okay so let me give a little history first. A few months back I had an issue with a flasing battery light and power steering light that went undiagnosed by the dealer as a bad battery cable and battery which ended up being an over charging alternator that ruined my ABS system, blinkers, and drivers side power window. Luckily the extended warranty covered everything but the window.

Anyway, so I went on a long trip this weekend and started to notice my battery light coming on every now and then. My Scanguage shows voltage is normal and ignition is normal. My battery, alternator, and positive cable with fuse is all less than a year old. I checked the battery and cables and ther is no corrosion or anything and the connections are tight. This week it has been very rare that it has come on but it does come on here and there. I did have all moy coils, wires, and plugs replaced but the car has been running better than ever.

Does anyone know how this light works exactly? The manual says to the charging system has a problem. Any input would be great.

 

Go have your alternator tested

 

I did at stunnazone and they said it was fine according to their machine. I plan on taking it to an alternator place just to double check.

 

haha you said "stunnazone" thats friggin hilarious!!!

 

If your red battery comes up
it means that the car is running of the batter
hence the alternator might be malfunctioning or charge is insufficient

drive long enough and the dash will dim as the battery gets weaker


hows your grounding and electrical cables?

 

The cables are tight (and one is new)and free of corrosion. I'm going to get the alternator tested tomorrow again.

 

Same exact thing is happening to me. Dealer replaced my battery and had me split the cost (as it's a consumable gah). $70 later and the battery light still comes up when I drive on the highway. I'm sure it's the alternator, even though it tested fine when they checked.

 

check the belt.

btw, have an extra alt if you need one..

beers

 

Ah, the belt. I can't believe I didn't think of that. Thanks!!!

 

I've been thinking Mazda should've gave us a *stronger* alternator than the 100amp we have.

 

Usless to take it too them... 90% of the time they think a bad alt is good.

Heck I have seen them test a alt with a blown regulator putting out 16+ volts and they said it was just fine.

 

Well, I checked the belt and it was tight so I removed the alternator and took it to an alternator shop and they tested it on the bench and said it was fine. I put it back in and drove my kids home and the light came on here and there. PIA.

 

when they said the test was fine, how many V did it output ?

like the others have said, some places consider *16v* to be "ok" when its not.

Have you check the dark current yet ?

 

I didn't get specs. I don't have a clue what the output should be. I guess I'll get the specs and go to shop again.

 

I forgot exactly what it was but, it should be around what maybe 14.7 ?

I completely forgot about the dark current tho. there might be something draining your battery the whole time.

 

12v and less would be battery only. Usually like 14.7 with the alternator working.

I just had Mazda replace my alternator a couple of months ago. Amazing how far you can get on just battery (but a new yellow top).

Might be time for a bigger alternator. If it is only 100 amps we should be stressing it here in AZ with all the fans and toys running all the time.

 

The stock is rated at 100amps. but as you might already know, that's just "on paper spec", that also means you'll never get 100 amp, the max output I will say is around 90~ ish Amps, on paper "spec" is always higher than "actual, real world" situation.

with all the heat we have under the hood, it will make it degrade even faster. (that thing runs at like 260-280 degrees, its even hotter than the engine itself!)

So after a couple of years you're left with a unit that can barely charge anything (if it charges at all)

 

to add to the previous: I ended up getting the rebuilt alternator, rebuilt but.....

Guess who is back? So on my way to the Texas8 run I almost had to dip out because my voltage dropped to 11.4 and my battery light came on so I slowed down and when i down shifted the voltage came back up and the battery light went off. So for the whole day she was fine no lights, etc.

So then on Sunday I took the kiddos home and the light came on and then would go off if I put it in Nuetral and revved it. This happened a few times throughout teh drive. When I got home I checked the alternator belt and everything seems great. I'm thinking my rebuilt (twice) alternator is going out again. I replaced the battery a month or so ago.

Any idea where the best place to get a new alternator is because the dealer wants a grip for it.

 

I dont think they sell brand new rx8 alternators anymore, not even from dealers. or was it the starter? I forgot.

Ask Mazmart.

 

I got my alternator replaced about 4 months ago because of the battery light issue which my car was having (sounds like what you are going through). It caused my car to suddenly shut off in the middle of the freeway while cruising at 70 mph. I had my car towed to the dealer and it was replaced with a brand new one under warranty. So I am guessing they still have them brand new...

My suggestion is not to drive the car at all when the battery light is on or blinking because its extremely dangerous and you will never know when it will give up on you.

 

Yeah it left me almost stranded a couple of times before but my Scanguage II saved me because I watch it constantly and noticed the voltage dropping. This is how I noticed it recently because its mounted front and center for me and I was paying close attention to my temps due to the spirited runs and the hot weather.

 

Dealership does sell new ones, ask me how I know.

 

dude it is your alt. my car was doing the same thing. but instead of pay for an over priced alt i went to the zone and got one. no problems wit it and the 8 feels better than when i first got it. and be carefull when driving wit that light on cuz everything goes. powes steering, abs, gauges start going bonkers. not safe at all. trust me i almost died.

 

yeah sounds like your alternator is bad and not pushing out the amperage that it needs to at normal rpm's

 

if u want a redneck way to test ur own alternator....take a screwdriver/or anything that's metal...and with the car running hold it close(the screwdriver) to the pulley/bolt on pulley of the alternator the magnetic field should pull the screwdriver in and make them stick to one another.....but b careful not to get the screwdriver caught in anything....

DISCLAIMER: I (04RX8MAN) AM NOT RESPONSIBLE FOR ANY INJURY TO YOURSELF OTHERS OR YOUR CAR.