Not charging and intermittent electrical issues

AECKARD45

MEMBER
2010 KIA RIO
1.6L
4 CYL
2WD
AUTOMATIC
155,000 MILES

Having a lot of issues with the electrical system. I'll try to stay on track with the timeline and if you have any questions i'll go into more detail.

The battery light would randomly briefly come on every once in a while, for about a month without any noticeable cause.

Right before total failure I was driving and after hitting the brakes pretty hard then the battery came on and stayed on for about 3 or 4 days straight. And then it shut off one day while I was driving.

I got a jump and luckily was able to make it home.

I took the battery out and charged it completely but the person who charged it for me put the cables on reversed and the windshield wipers came on and a couple of other random things when it was connected like that, and the car wasn't even on. I was not outside so I couldn't really tell you much more about it

When I got to the car, the battery was in it and unplugged but I noticed it was backwards so when I plugged it in, everything was gone. I had no heat, no radio, no rear defrosts and now the battery isn't charging.

(Before you tell me, I know the risks of doing this) so I was taking the battery out every time I got home and charging it and then would put it back in to drive. Still, no power to the previously mentioned parts.

I replaced the radio fuse, and it began working again.

I noticed there was a broken wire that connects to the inside body near the driver's side fender area. I am not 100% where it is coming from because it goes into a bundle of other wires, but it seems to obviously be a ground wire of some sort about 6 gauge and black copper wire.

I bought a fusible link for the positive battery terminal, changed the alternator 125amp fusible link under the hood in fuse box, filled up the coolant and when I started it up, it was like a miracle everything was working properly.

That was very short lived and the next time I drove it, it wasn't charging again but the battery was lasting a lot longer than it did.

But everything else was still working fine.

The 125amp multi fuse and the positive terminal fusible link both seemed to be working still but that ground had come undone because I didn't have the stuff to do it properly at the time, so it was a very temporary fix that I needed to change.

So, the battery, the connection from battery and the fuse box are both at 12.7ish volts but they are the same reading.

The engine to the battery is also the same I believe

(Going off of memory with a lot of different tests and stuff i've done)

Battery to alternator there is nothing, no reading at all

But the alternator is spinning, and the test light shows it has power.

Battery was installed reversed by AutoZone guys and guess what, no heat, no radio, rear defrost and still not charging.

It's very cold and dark but I replaced the alternator fuse again like I did last time but nothing changed.

What do I do? The battery and alternator and starter all tested good.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

Since the battery was installed backward a few times, there could be a few causes. However, are the battery terminals both clean and tight?

First, I attached the wiring schematic below of the charging system. If I understand, you replaced the 120-amp fusible link from which the alternator receives power. Do you have power at the black wire on the alternator?

If you do, (and I believe you indicate you do), the alternator may have an intermittent fault. Basically, it works sometimes and not others.

So, here is what I need you to do. When the light is on, I need you to check the voltage at the battery. With the engine running, you should see approximately 14v. We need to confirm it is or isn't charging when the light turns on. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

There is a chance the pre-excitation resister was damaged. Also, confirm fuse 10 in the fuse box in the vehicle is good and has power. The alternator won't begin charging unless it receives "excitation" voltage to set up the initial magnetism in the alternator's rotor.

Let me know what you find. Also, pic three shows the fuse to check in the fuse box. Also, the other thing I highlighted I believe is the pre-excitation resister. Make sure it is in good condition and has no evidence of damage.

Joe

See pics below.

Images (Click to make bigger)