Battery and brake light on

[shazapple]

Is this a sign of my alternator going?

Strange thing is that the battery reads at 15.35V (with the car off), and it looks like there's some battery acid around.

Can alternators go bad both ways? (not charging enough vs charging too much)

[Plays_with_Toys]

To check your alternator is to I believe 14 volts with the car on and 12.66 or so with it off.

That seems like a really high voltage for your battery and the car off. Did you have the alternator recall performed on your car before?

[shazapple]

I turned the car on and the voltage stayed pretty constant between 15.35 and 15.95V no matter how much I revved the engine.

Of course, calling the Subaru dealership was completely useless.

[LegacyRob]

Of course, calling the Subaru dealership was completely useless.

Who did you talk to up there? I always talk to James if I need help there. He's been very good to me.

[ProdriveDreams]

I recently had my alternator go, and both of those lights did come on. The answer to your question is yes, alternators can go bad from overcharging. The way this usually happens is that there is a harness with two wires connected to your regulator in your alternator (not the one that bolts to the top of the alternator the other one.) These are used to sense voltage at the battery to determine how much amperage the alternator should be spitting out. When these wires get corroded then a false low voltage signal is delivered and your regulator puts the alternator to work. The problem is your battery is actually at full charge, so all its doing is killing your battery by boiling the water inside your battery out, and putting an immense strain on your alternator.

Additionally though, corrosion on the wire that runs to the positive side of the battery can also put strain on your alternator because it is putting out the right amperage, but not all of it is reaching the battery meaning it has to run harder more often. However this does not usually result in the extreme over charging you have eexperienced.

I would recomend replacing the alternator, BUT also doing a voltage drop test on the regulator lines with the car running. Anything in excess of .2-.3 volts is too much and will interfere with correct operation of your regulator circuit. The thing is if you dont correct the problem then you will blow the next alternator too. there is a chance that there is no corrosion and just your regulator has crapped out. If your battery is not "maintenance free" check the electrolyte levels in each cell and top off with distilled water if necessary. also have it tested at a place like autozone who will do it for free, just incase.

good luck!

[shazapple]

Well, turns out not only is my alternator broke but so is my Volt meter! :lol: it always reads 15~ volts. When I measured it with a normal meter I got 11.9 and no change from RPM change.

The Subaru Dealership has reman ones for $112 plus tax. Is this a decent price?

[Kraziken]

Well, turns out not only is my alternator broke but so is my Volt meter! :lol: it always reads 15~ volts. When I measured it with a normal meter I got 11.9 and no change from RPM change.

The Subaru Dealership has reman ones for $112 plus tax. Is this a decent price?

I think that is about normal, and you can take your bad one back to them for a core refund? I did that recently, but I can't recall the total cost after I bought the reman and got a refund.