Ok. I just bought a new red-top optima for my 2002 wrx sport wagon. Something isn't right with my voltage.

At idle the voltage at the alt reads 14.3v
At idle the voltage at the battery reads 14.25v

Car off sitting for 5 minutes the voltage at the alt reads 11.5v
Car off sitting for 5 minutes the voltage at the Battery reads 11.5v

When off, the voltage readings slowly decline. Making starts very sluggish to the point of almost not starting. I deliver pizzas and when i go in to deliver and come back out, the car is sluggish. This is after 10 minutes of driving. Stop for 2-5 minutes. Start the car and it barely starts.

This is a 2-3 week old battery optima red-top. I don't want to ruin it. Is this the battery or the alt? My guess is with the alt. Any advice or knowledge in this area would be very much appreciated. I have searched and found variables, but looking for some comparison.

Thanks,
- Justin K.

What have you done to the car that touches the electrical system, list anything and everything.

The voltage reading while running appears to indicate the alternator is working. However it is possible to have bad diodes in the alternator and still see the correct voltage on a meter, although it wouldn't be charging correctly. Only a shop with the proper equipment (scope) would be able to check for this type of problem.
The reading when off is definitely too low. At rest the battery should not read less than 12.5V.
Have you checked for excessive parasitic, or standby, drain in the car? This can be done by disconnecting one of the battery terminals and connecting a milliameter between the terminal and battery post. With the car off, key out, all doors and trunk closed, you should not see a drain of more than about 20-30 milliamps. If it is much higher, say in the hundreds of milliamps or more, that is a problem and must be corrected. However, from what you are saying the battery is draining at a much faster rate than a high standby drain would cause so something else is probably wrong. Still worth checking to be sure.
It is also entirely possible that the Red Top you got is defective, it does happen. I'd suggest taking it to a shop that can properly check both the battery and alternator, and if it does turn out to be the battery then contact the vendor you purchased it from and get it exchanged.

I have a V1 tapped into the map light switched power. Grounded to the screw that holds the map light up there.

I had/have a laser blinder unit in the car. But it is not in the car at the moment. The wires are still there but switched off and the leads are taped up.

The clock wiring has been seperated from connector and has wire-nut's on all 4 wires.

I have hella horns that I ran off the stock wiring and grounded to the radiator mount screws. I did not use the provided relay.

I also re-ran a ground from my driver side foglight. I have been popping bulbs within a month of full-time use, so I re-ran the ground wire to the radiator mount screw. I put a wire nut on the existing ground and taped it off.

I have a grounding kit. Goes to the engine wall next to the battery. Then, it goes to the transmission and on to the intake manifold driver side. Then on to the alternator and on to the passenger side of the intake manifold and finally to the passenger side strut top screw.

My laser blinder unit was ran by the old clock power until I started having major drops in voltage while the car was running, sitting at stoplights. The V1 would flicker on and off while idleing at stoplights. Usually when the fan came on. Then I tapped it into the radio's switched power just to see if it would make any difference and it didn't.

Then I replaced the battery and it has been tempermental at best with the voltage. Now its come down to it doesn't want to start very easily.

I think that's the gist of it.

Thanks,
- Justin K.

As Mulder says, it's most likely something drawing power - and to drain the battery enough so starts are weak after only 5 minutes is going to take a fairly big power draw. One thing you can easily do is to disconnect the battery and see if it's voltage discharges by itself. All you need do is to pull off one battery connector. The battery should not read lower than 12.5 volts or so, and should certainly not discharge. If it does, it's defective.

Assuming the battery does NOT discharge, it's gotta be something drawing power. Have you got anything aftermarket (like amplifiers or inverters) installed?

I just went out to my car after it had been sitting for only an hour. The readings I got from the multimeter were 10.45 at the alternator and battery. This was before I got in a barely started it. :-(

That is very bad. I agree with Alan, drive the car around enough to at least give the battery a good surface charge (assuming the alternator is working). Then, disconnect the battery immediately after parking and shutting the engine off. Come back a bit later and check the battery voltage, if it's ok you know the problem is in the car, if it's still low it is likely a bad battery.

No aftermarket amps or anything that draws big power. I'll take a better look at the alternator and battery when I get home. I have an appointment at the dealership tmorrow. I just want to figure it before that happens. If I could just replace the alternator and fix it, that would be best. Instead of the dealership charge me up the wazoo.

If you just throw parts at it you may be wasting your money. It may indeed turn out to be the alternator (they can go bad in a way that causes battery discharge), but if you go and buy one on speculation and it isn't the problem, most places will not take returns on electrical items so you'll be stuck with it.

You should check all those installations that you just mentioned, as they may be the culprit, especially if you had problems with any of them popping fuses. I'm willing to bet that if it's not the alternator or battery, it's one of them. And wire nuts are really not the thing to use in car installations. There are crimp on terminators that work real well and will give a longer hold time.

Ok...I did the battery test. I came home, unhooked the cable and it was at 12.27v. I let it sit for about a half hour. It's now down to 10.66v. So, the battery was draining all by itself. I also check the amps between the terminal and the power cable. It was a fairly steady .26. Should I just replace the battery? I kinda need a quick fic as I drive my car for work, and I work again at 5!

Thanks,
- Justin K.

My fog light has been popping bulbs. Not fuses. And it still does about once a month. But, I got the foggy used from an australian wrx, same year. Who knows about the foglight. I've tried to figure that out as well with no luck. But yeah. I'm just gonna run over to batteries plus and have them replace the thing and hope for the best.

If the battery discharged itself from 12.27 to 10.66 it's bad.

I went to batteries plus and they gave me a loaner. They're gonna charge and test my optima. This loaner is working just fine...no discharging or anything. Works just how it should :) if the optima is bad, they will replace it for me. So that's cool. :)

Thanks guys for all the help! Really made a difference in me figuring out this problem ;)

- Justin

Was your drain actually .26 amps? If it was that's too high, it should be an order of magnitude less like .026. That would be 26 milliamps vs. 260 milliamps. A 260 milliamp drain will discharge the battery over several days if the car is not driven. If your drain is indeed that high you need to take care of it.
Anyway, glad to see you were able to isolate the battery as the problem.

Well, the setting on the mulitmeter was 10A. And the reading was 0.26

Test it again to confirm. If it's really 260 milliamps then you need to investigate the source of that drain, as it is excessive.
When checking, wait several minutes after the key is removed and the car locked to see if the drain drops down after a while. If it stays high, start investigating. Begin with the trunk light as this is a common source of extra drain, make sure it is going off when the trunk is closed. One way to tell is to take out the bulb and see if the drain then goes down. If that's not it, begin disconnecting things one by one until the culprit is found. Start with your aftermarket stuff.

If this is the case, would the parasitic drain on the battery cause the battery to become unable to hold a charge?

it was a 2 week old battery and I drive all the time. Its just an annoying thing to figure out! :)

If this is the case, would the parasitic drain on the battery cause the battery to become unable to hold a charge?

Only if it went on for a very long time, and the car was not driven frequently. With that amount of drain, if the car is driven on a daily basis, or even once every few days, you would never know there was a problem. This assumes that you are taking decent length trips and not just driving around the block.
If you do have a drain problem I don't think it's related to your dead battery issue. It sounds like your battery is just NG.

I'll check it again after I get home from work and see what the readings are. I deliver pizzas in it, and drive 20 minutes to work. So, I'm driving it all the time.

Batteries plus has yet to get back to me on my battery. We'll see I guess.

Thanks,
- Justin K.

I have a V1 tapped into the map light switched power.

the maplight is constant +12v (not switched) - if you hooked something up to the maplight power lead, it won't turn off when you turn off the car.

also - 12v car batteries will slowly depolarize with time from their charge potential - so if you are holding at 14.5 volts to charge, as soon as you pull the leads you would measure 14.5 (minus any voltage due to IR drop at the connections) then decay down to 12.6-13 volts or so - it should never be below 12 volts.

For some reason I thought that was switched. Now that I think about it, I can use my map light at any time :-/ duh. The power on the V1 turns off with the car...but if it's not switched it could still draw? I'll test it out with my multimeter :) damn thing is getting a workout! :)

I tested the amps with the v1 off and on when the car was shut off, and there was no difference in the amps that were being drawn.

if you grabbed power from the mirror harness which is up there, that is switched power, so maybe that's what you grabbed!

Yep, that's what I tapped. Not the actual map lights :-/