Battery losing voltage

[Mignatius]

06 4l…A couple days ago my check gauges light came on followed by a drop in voltage while driving, got it home and it died. Called AAA he gave me a jump and battery immediately starting losing power and engine started to putter out. So I replaced the alternator. Got a jump and battery still not charging. Called triple AAA, battery basically shot, bought a new battery. Turned on to 12.6 volts all good. Drove it later a short distance and saw it hovering Between 12.6 and 12.7, today it dropped to 11.6 on the 3 mile drive to work and to 10.2 on the drive back home… cables are old but I can’t find any broken connections(although I will be relaxing them as soon as I have a chance with a set from jeep cables) is there a fuse that I could have shorted out or something else I’m missing?

 

[WestCoastDan]

You’ve replaced the alternator & battery, so the only thing left (on that side of things) are the main cables and wiring between the alternator and battery.

BTW, a bad (blown/open) fuse will not drop your battery voltage and a ‘shorted fuse’ is quite common, since that’s what they are; a conductor that fails in an OPEN condition to prevent current flow when it exceeds a given amperage.

I suspect poor charging due to old wiring, and while driving you were only using power from the battery.
The output from the new alternator is probably not charging the battery.

Simple test is to start the vehicle and measure the voltage across the battery posts to see what you have.
Anything near 14.0 means the alternator output is charging the battery, anything less means there is an issue - likely a bad connection and/or corroded, craked wiring.

 

[AjRagno]

The check gauges light will set a code. If you cycle the ignition from off to on 3 times the code will be displayed in the odometer readout.

I’m guessing you’ll see P0622, which is the generator field wire shorting to ground.

 

[Waldeck]

Sounds like a bad or broken ground. A bad Battery will kill your alternator, maybe recheck your new alternator.