Alternator problem (or something else)

[Maykelpags]

Alternator problem (or something else)

Weeks ago the negative terminal got corroded. So i bought me a new battery.
But the next day the battery light turned on, and many of my friends said it must be the alternator.
I check the part that i need and boy that alternator is expensive!
So i bought me a one at a junkyard for $35 (it came from a 2015 mine was 2012)

Before i took my old one off, i checked the voltage and the amount of charge it does.

My old one was charging around 14.7-14.8 volts so i thought it was overcharging because the battery light showing up on the dashboard.
And the one on junkyard is charging 13.1 to13.2 volts and still, the battery light shows up.
Both stays at 12.5 when turned off.

Now before i buy a new one. Im gonna need an opinion wether theres other reason why it does it. Or both alternator are just bad.
It runs on both alternator but i dont wanna cause more problem without knowing it.

Any roast or suggestions might help 😂

 

[Handy Andy]

Roast?

Hmmm...no not roast, else you might be toast if we can't keep you running...

The "battery light" usually means that the Charging system has a problem, as to what though? Might need to investigate more into the battery and ground cable, and see where the positive cable goes into that "black box" just in front of the battery?

But that requires all that stuff you took off just to put the battery in, back off, and pull the battery out, so you can see where the distribution box assembly and it's conditions is in?

We are presuming you've checked the alternators pulley is fixed onto the ROTOR shaft and turns with the serpentine belt.

The panel is where the main Positive cable goes into.
But the Alternator and Starter - let alone other sub-systems
are getting their power from this panel.
The Blue arrow shows where one of the lift tabs are at.
Once the battery is out, this panel can be inspected more closely.​

So the choice it yours, but this system uses the positive cable to work into a Buss bar type of branching system that allows the bigger AWG gauge conductors to merge into this unit - so this takes the power from the battery and also places power back into it. So for you to see the charging Battery light, you might want to research in the owners manual on how to reset the battery monitor.

This Battery light is also a BMS system, but you live in the USA this may not directly apply to you. So the BMS system "checks" and remembers the voltage of the battery it sees in a window of time AFTER the ignition is off, and even while the engine is running - this timed checking process happens behind the scenes. You don't notice it. So for you to see the battery dash light on, and swapping alternators didn't seem to fix it - you will have to dig deeper or have a service department look at the cables to the Starter and Alternator and verify their integrity and nothing is corroded off or blown open - even back at the Battery Junction Box that adssembly is - by that battery.

The the Reset for the Battery Monitor, if you have one - is a set proceedure that you turn on the igntion, press a set of button features as a given sequence - the battery Monitor then resets.

How do you know you have a Battery monitor - you woudl know by NOT have the negative ground cable of the battery - directly to the ground bolt on the upper drivers side strut housing. It would have a device integrated into the Negative cable that in itself is easily noticeable that something like a relay or cutout - that is the monitor and if you see it, then you have to do the BMS reset function, should be in the manual - else see your dealer to have them show you that sequence you'll need to do every time you replace the battery.