RX7xFD3S

Hello all. I have a rather WEIRD question today..

I went to my local mechanic to switch exhaust. Working.

I went to my local gas station to get gas. Working.

I took it to another mechanic for check up. Working.

I tried to levae the mechanic. Not working.

Battery seemed to have died. So I go and get the battery replaced. Still not working.

Next day I come back. Battery completely drained.


I checked all my lights and everything. A/C and stuff and nothing is turned on YET my car STILL drained all the battery in one night. And this happened right when I took the car to my mechanic so here is my question:

Why does the battery keep dying? When I recharged the battery and cranked it, it would turn over yet it wouldn't start. Thinking it wasn't getting any spark, I changed the spark plugs. Didn't help at all. It just sounds like the battery is always weak.

Can anyone help me on what would cause this?

Oh and I tried to deflood it too. Not the problem.

farberio

iTrader: (7)

Probably a short somewhere, it is really old wiring.

Get a copy of the wiring diagram and a DMM and start poking around.

francogt1

iTrader: (2)

alternator?

farberio

iTrader: (7)

Battery drained while the car sat there, so the alternator is probably not at fault.

HAILERS

Are you sure your turning the key all the way to Lock when you take it out? Try that. But if the batt died in just a hour or two after it was running, then either the alternator is marginal or batt is bad. But you replaced the battery, so that's not it.

Does your alternator read well over 12v on the stock gauge when you have the engine running? It could be barely putting out causing the batt to go flat.

If even the NEW battery sounds weak when you try to star the car, it could be several things. One would be a tired starter. Another would be the cables on the starter are loose. The large cable attached to the starters long outboard attach bolt is the ground for the starter AND everything else on the car. Make sure it's bolted down good. There's a possibility that cable isn't on the long starter bolt anymore and is now on one of the transmission bolts nearby. That's alright. Just make sure it's tight.

It sounds to me like its the alternator. The question about the volt gauge would help. As in, answer if the stock gauge reads well over 12v or not when the engine is running and the rpms are at 2500rpm.

RX7xFD3S

If the car starts, the car starts fine and it'll run smooth.

The volt gauge reads around 11 ish. And this problem happened after I took it to a mechanic so I don't know what the **** they did to it.

But the battery isn't dying due to the alternator. But the car dies without the car even running. And it's dying over night.

I had to push my car home so I'll look at it tomorrow.

Icemark

Blown output diode will cause the alt to stay active and drain the battery. This is most common when a S5 or S6 alt being wired into a S4 incorrectly but can also happen on both S5 and S6 models with that diode being bad.

HAILERS

You can prove what Icemark said. Fully charge the battery. Then remove the large ouput wire off the alternator and let it sit overnight like that. Leave the battery fully connected up.

Then the next morning, put the large cable back on the alternator and start the engine. If it starts then you've a bad alternator.

But golly gee. You say the voltmeter reads in the low 11 range. That right there says bad alternator. OR the small plug is off the rear of the alternator.

Quick question. Do all the warning lights come on when you turn the key to ON, engine OFF? They should. And when you start the engine, do all the warning lights go off? Especially the BATT light off?????

What did the mechanics work on? Could be them or it could be happenstance. No way to tell.

RX7xFD3S

Umm the lights come on and when I crank the engine, everything shuts off. Then I give it like 15 seconds and try it again, the lights come back on but does the same thing again. Does that mean I have a bad alternator and that the alternator is staying on even when my engine is off?

HAILERS

If you go to Start, and everything shuts off, then it's either a bad battery or one of the battery cables is not connected very good. Or the battery is just flat or has a bad cell in it.

IF the engine starts, and the volt gauge reads only 11-12 volts, then the alternator isn't putting out.

You ought to give the following a try. Fully charge the battery. Then remove the large cable on the alternator and set it to the side (it's HOT all the time, so be sure it's not touching anything. Then let it sit til the morning where upon you'll reattach the large cable and have another go at starting. IF it starts it would seem to me the alternator is killing the battery. As in draining it down overnight. Like IceMark said a few posts ago.

A running alternator puts out 14vdc, not 11 or 12vdc.

I asked about the warning light coming on (all) when the key is put to ON, just to see if you had the small plug on the back of the alternator on...or not. You do.