Alternator

Are you sure it's defective? Chrysler alternators give extremely little trouble, but when they do, it's usually worn brushes. On most models, they can be replaced without removing the alternator from the engine.

94,000 miles is too soon to have worn brushes. Have you actually done any diagnosis or are you just guessing the alternator is bad? What is the symptom?

Caradiodoc

Sorry for the long delay. You are extremely lucky the engine shut off when you disconnected the battery. Doing that while the engine is running was a test used decades ago by people who didn't understand how charging systems worked.

If your alternator is NOT defective, removing the battery cable removes the cushion that helps regulate system voltage. The voltage produced by a good alternator varies between around 8 to 16 volts. The battery smooths out those pulses and gives the voltage regulator a steady voltage to watch. Without the battery, the regulator sees the pulsing drops to 10 volts and tries to increase output voltage to 13.75 to 14.75. If you increase engine rpm while that is happening, the output voltage can very easily exceed 30 volts. Any guess what happens to the engine computer, body computer, remote keyless entry computer, air bag computer, anti-lock brake controller, and electronic radiator fan relay when system voltage goes too high? On older, more reliable cars, the worst that would happen was you'd burn out any light bulbs that were turned on at that time. On newer cars, you can easily do thousands of dollars worth of damage in a few seconds. Please don't do that test again.

The best way to tell if your charging system is working is to measure battery voltage while the engine is running. With the engine off, battery voltage should be near 12.6 volts if it's fully charged. With the engine running, it must stay between 13.75 and 14.75 volts. Lower than 13.75 volts and the battery will never fully charge. Over 14.75 volts and water will start to boil out. Don't panic if your voltage is a little out of that range. If the battery was run down, the system voltage will likely be less than 13.75 volts, but you will see it rise as the battery recharges.

Read the guide below, not vehicle specific but gives good info on alternator change out

https://www.2carpros.com/articles/how-to-replace-an-alternator

Vehicle specific instructions- Manual doesn't list exact tools required. Metric wrench/socket set will do the trick

Removal
1. Disconnect battery negative cable.
2. Loosen the jam nut and adjustment bolt,
3. Raise vehicle and support.
4. Remove accessory drive splash shield.
5. Loosen the lower mounting bolt.
6. Remove the generator drive belt.
7. Disconnect the generator field circuit wiring connector. Push the RED locking tab to release.
8. Remove the B+ terminal nut and wire.
9. Remove the upper and lower mounting bolt and move generator off of pivot bracket.
10. Remove pivot bracket.
11. Remove Generator through wheel well.

INSTALLATION
1. Install generator through wheel well.
2. Install lower pivot bracket and tighten bolts to 54 Nm (40 ft. lbs.).
3. Loose install the upper and lower mounting bolts.
4. Connect the generator field circuit wiring connector. Push the RED locking tab to lock.
5. Install the B+ terminal nut and wire.
6. Install the generator drive belt.
7. Lower vehicle.
8. Tension belt.
9. Tighten adjustment bolt.
10. Tighten the jam nut
11. Raise vehicle and support.
12. Tighten lower mounting bolt and tighten bolts to 54 Nm (40 ft. lbs.).
13. Install splash shield.
14. Lower vehicle.
15. Connect battery cable.

See diagrams below for further help

Welcome, use a digital voltmeter, take a reading across the battery posts, everything turned off, note the reading. Start the vehicle, take second reading across the battery posts, the second reading should be higher than the first, if charging system is working. Some of the national brand autostores will test alternator. If the alternator checks good, you'll have to check wiring circuits.

Overloading the charging system could bring on early failure. This can be due to a bad battery, not recharging the battery before installing the new alternator or jump starting other vehicles.

Let me add to that the installation of a high powered, aftermarket stereo system.

Good observation about it going to 18 volts. Without that important information, the most common cause of a charging problem is worn brushes due to high mileage. That would cause an undercharge condition.

There are only four things that can cause an overcharge condition, and you replaced two of them already. The first is a grounded brush in the alternator, or more likely, a frayed wire on that terminal that is touching the case. The second, less likely cause is a shorted voltage regulator inside the engine computer. They do not fail very often because there are too many safeguards built in. The third cause is a break in the system voltage sensing wire going to the computer. Often other things won't work because they use the same circuit for their power supply. The fourth, and possibly the most likely cause of the problem is a grounded wire.

The first step in finding this intermittent problem is to measure the voltages on the two small wires bolted to the back of the alternator. One will have full battery voltage, but only two times. First, for about two seconds after you turn on the ignition switch, then it will go back to 0 volts. The voltage will appear again when the engine is rotating, (cranking or running). You will need the engine running to take these measurements.

The second wire will have less than battery voltage, but it will not be 0 volts. The voltage regulator will draw the voltage down, typically to 4 - 11 volts. This is the wire you must monitor. If the problem shows up very infrequently, tie a long wire to this terminal and run it inside the car to a voltmeter with the meter's black lead grounded to the body. Observe the voltage when the problem occurs.

Even if the voltage regulator is shorted, voltage on that wire will not go down to 0 volts. Anything related to a defective regulator or the voltage sensing wire will result in 2 - 4 volts on that wire. If you find 0 volts when the problem occurs, inspect the wiring harness for a place it is laying on a hot exhaust manifold or is cut on a sharp metal bracket. The wire's insulation could also be rubbed through and the wire is touching bare metal. You might be able to make the problem act up by moving the harnesses around or rocking the engine. For convenience, turn on the headlights so you can see the change when you make the problem act up. You will also hear the alternator whine when it becomes "full-fielded".

Caradiodoc