I have had the battery & the alternator "shop-tested" (twice) now & they are both "good". My Jeep will run fine for a few miles/ minutes untill "out of the blue" my voltage gauge drops down to nothing & my dash light "check gauges" illuminates. I had this prob. last Saturday & the parts house, nor myself could figure it out. So, I cleaned up the corrosion from my batt. post's & on my batt. terminals, hooked everything back up & I had no problem untill yesterday (Thursday). I have pulled off the battery clamps from the battery "while engines running" & seconds later -it dies !! My multimeter will read 12.16 volts on the battery terminals "while engines running", I know this is too low. Fusiable-link was "continuity tested" & was "fine". My cuzins pretty knowledgeable in automotive problems- He tested things w/ me & told me to look into the the "Ignition Switch' Situation !! The electrical-problem is somewhere between the Battery & the Alternator. & all these various parts I am pretty un-familiar w/. -my vehicle is a 1997 Jeep Wrangler SE, 4-cyl. 2.5 ltr. Fuel-Injected engine, w/ a manual trannsmission. Anyfeedback is greatly appreciated !! Thank You Mark A. Porter

BATTERY LIGHT!: Hello All! Today I Was Driving in a Rainstorm, and... (2carpros.com)

Compass alternator won't charge... bad PCM? ' My Jeep Compass Forum

Compass: I replaced the alternator in my 2007 Jeep Compass (justanswer.com)

These link talk about Issue with fusible link and wire to pcm or pcm.
Just a thought check for good clean grounds, tight clean connection and battery fully charged.
Not sure but hope this may help in some way. Good luck

Sounds like your alternator is going out. Here is a simple test: Turn your car on. With engine running, disconnect the positive side of the battery, making sure it does not touch anything metal. Keep wipers, radio, lights, etc off. If the car dies within about 3 minutes, then your alternator is bad. Reconnect the battery and head to the shop using as little as possible from the battery, or you may end up on the side of the road.

sounds like a regulator malfunction to me..need to connect a battery/alternator tester to the system and see if the regulator is bad.. this will cause full charge of the alternator to enter the system.. this uses the battery as a regulator and will cause overheating of wires and relays..if the alternator can be removed and tested separately(most can), do this and see if this is the case..replace if bad..good luck..

You may need a shop manual to get the wiring diagrams and test procedures.
The alternator output should be around 14 volts unless you have a heavy load such as headlights or the heater blower on high.
If voltage goes above 14 the regulator could be faulty even tho you say the alternator checked out ok on a bench test.
The regulator gets a power signal from the gauge on the dash to energize it. There could be a loose connection somewhere in the charging system, or something in the instrument cluster. Even the key switch could be a factor.

sounds like the alternator is bad again. Can you take it off and have it tested?

To begin with, a 45minute charge is insufficient to fully charge a battery. A "quick charge" can damage the battery by overheating the plates, causing them to warp and shed lots of oxide that falls to the bottom and acts as a short. I've found that charging at 10 amps or less for up to six hours works best. After charging fully, the battery must be load tested (generally a 200amp load is applied and the battery voltage should not fall below 9.5 volts...test is under 15 seconds or it can damage a good battery.)
Next is the charging system. I use a simple but fairly reliable method for doing this. With the car running, place a volt meter on the battery and read voltage with all accessories off. Volts should be under 14 and above 13...generally about 13.5....Then turn on everything electrical in the car. Volts should not be less than 12.9 but 12.5 is OK as long as it does not drop further. After running for about ten minutes, voltage should not creep downward below the 12.5 mark. It may vary as regulator comes on and off but it should not drop. When some shops check an alternator, they "full field" it...this tells you that the alternator itself is able to charge the battery but does not tell you if the regulator is working correctly.
If the voltage is below specifications either the alternator or voltage regulator has or is failing.
On some Jeeps, the voltage regulator is in the computer (I know...really bright) and if it is it cannot be replaced separately. If regulator is inside the alternator you can change it or replace the alternator.
You can also have something in the system drawing down the battery, but from what you wrote, I don't think you have a problem there.

Check battery (must have a min of 12v and be able to hold at least 9.5v at a 200amp load) Check alternator output: must not charge below 12.9v with all accessories on with engine running. Must not charge above 14v at any time.
Check starter draw: must not drop below 9.5v when cranking. Do these tests in order. First can be done at any shop. both other tests are not valid if battery cannot pass first test. Second and third test can be done with any volt meter attached to the battery.

The problem sounds intermittent, if you put volt meter on the battery while it is at that 19volt mark/reading(on the gauge cluster) you will be able to see if it is true. If your alternator is really charging over 16volts the lights should be getting brighter then usual and/or they are burning out. Find out ASAP, if the alternator has a defective voltage regulator, it needs to be replaced. Prolong use will damage components.

Check and clean all connections to & from battery, as in the other ends of cables as well. Make sure starter wires are all in good shape & tight as well. When you hear that click, try to locate area or relay doing the clicking. It may just be a faulty relay. Sometimes it's as simple as removing it and plugging it back in to clean the connection. Do you by chance have a 12volt DC test light to test draw on battery?

How long did the 2nd alt. last before it died? The voltage regulator is, I believe, attached to the alternator. Have u had the voltage regulator checked?