So heres the thing. My S4 FC used to have starting problems with a dieing starter, I thought it was just the battery going low from flooding then cranking alot to deflood it when starting. But later on I noticed the starter would crank slowly even with my friends car jumping. I replaced the starter and it started up like a beast! Faster then my moms civic in fact.

Heres the trouble, the FC was driving fine for a while but later on the battery started to die out. At this time the volt meter on the dash read about 8-9 volts under no load with engine off. I knew the alternator belt needed replacing because it was covered in cracks and kinda glazing. I replaced the alternator belt had my friend jump it again and I drove for a good long Hwy drive to charge it up again. 5 days later its completely dead it is now reading at 0 or 1 volt (needle moving barely)
What do you guys recommend?

 

Test the alternator.

 

Go to an autozone to get this done for free, also get them to test your battery as well.

 

+1 You can pretty much go to any big autoparts store and have it check for free

 

I just put a multi meter to the alternator and its making 14v lowest and 14.2v highest(Ive recorded so far.) The battery is pretty new and it was barely used back when my friend bought it. The battery is now charged (from driving) and its putting out 12.89v on the multi meter. I heard a short may be draining it such as the ignition, so Im currently looking for a short somewhere that might be doing it. During my search today I noticed a click like a relay or something whenever I undid the battery. This was after I did the lazy eye fuse trick. so I undid the lazy eye and no more clicking. Also the battery's voltage jumps when I pull the "head" fuse in the engine bay. Can you guys point me towards some common shorts and how to fix em? Also if I can do anything to prevent loosing charge for the time being until I fix the short.

P.S. I will post a list of volts running through all of the fuses in the bay and try the cabin ones if i have more time.

 

The car can run without the battery hooked up too. So I doubt its the alternator. Just checked the alternator this morning after driving to school and its making 14.48v now.

 

That's not the best test. Try and get out of the habit of using that test.

The engine is controlled by a computer. The alternator puts out very "noisy" power. That is to say, it's not pure 12V. It fluctuates up and down a lot.

The battery acts like a filter to get rid of this noise.

Older cars like the RX-7 have a very primitive computer, so it most likely won't gut hurt... But try that on a later 2000's car and it may stall out or you may eat the ECU.



That being said, I'd look closely at your battery cables. If he cables are bad, how is the battery going to be charged? How will it supply power to the car?

Look into buying a cheap volt/ohm/current meter. See what voltage is actually getting to the battery terminals. (Car's volt gauge, aside from being inaccurate, gets its readings from the electrical system, not directly off the battery terminals.

Inspect for corrosion where the wire enters the terminal.

Also, look for power drains.

Most Volt/Ohm meters include a small current function. (Reads Milliamps... uA)

Remove the ground terminal of the battery. Touch the negative probe (Black) of the meter to the battery terminal and the positive probe (Red) to the cable you took off... (It helps to have clip leads.)

With everything hooked up, touch the cable to the battery terminal and then remove it. Watch the reading on the meter. Anything more than about half an amp (500 uA) means something is on... A light bulb, some sort of accessory, something...

Start pulling fuses until the current goes down.

Report back.

 

The battery completely unhooked now reads a strong 12.7-12.9 every time before I start and after driving its alittle higher.

To, Pele
I've been making all of my voltage measurements with a mutimeter (volt meter with all those gadgets too? I think?) popping my bonnet everytime before i drive and taking measurements like that.

As for the cables those seem to be fine, and in good shape with no corrosion. Ill do what you mentioned and try measuring the current going through the negative terminal. Im just having trouble figuring out how to use my meter. What mA setting should I try and set it on? Just worried about burning it out or something.

 

Rule of thumb with a multi-meter, Always start out at the HIGHEST setting when working with an unknown and work your way down.

Does it have a 10 AMP setting?

Is it a digital meter?