Wierd Electrical Problem

I have a 97 XJ 4.0 Automatic... the other day the factory remote keyless entry would not unlock the doors. It sorta tried but almost seemed like there just wasn't enough juice to get it done. Then I started the Jeep only it was much harder to start than usual... I had to give it gas and feather the throttle for a little bit so the engine wouldn't die (and it's fuel injected) so anyway then everything was fine... all worked well.

Next day, similar deal happens only this time once I got it started and was driving my "Check Gauges" light came on and I noticed my battery gauge was pegged at the max voltage of 19 (I think it goes to 19) and then after 30 seconds it dropped back to the middle area and was fine.

Any ideas? Does this sound like a battery problem, alternator, regulator, or something else?

Integrated voltage regulator in the alternator is normally the 19v problem. Sometimes a cell in the battery that is starting to go open can cause a high reading on the voltage. Have the battery checked at Autozone or the like.

Now the keyless not working when the engine isn't running, is a different issue.

Valid, except from 1991-on the alternators are externally-regulated by a section of the PCM.

For some reason, the lock actuators seem to draw an awful lot of power - so if the battery charge isn't up to scratch, this will manifest there (as well as the long crank you reported.)

Check the battery with a hydrometer (checks the density of the fluid - an accurate reading of acid concentration and therefore state fo charge) for consistency across cells, and check the alternator output directly with a good voltmeter (digital or analogue OK - just don't rely on the one in the panel.)

I'd be inclined to say you're losing a cell in the battery - which you'll notice with the hydrometer. One cell (or more!) will read as several points less concentrated than the rest. A variation of up to .005 sp. gr. (what you're measuring with the hydrometer,) is acceptable, as I recall. More than that indicates a problem.

Nominal output voltage at the alternator should be 13.5-14.5VDC.

5-90

I'm going to go buy a hydrometer... if it is indeed my battery... I had been planning to go with an Optima... what color should I get? I don't have a bunch of extra accessories but may add some lights in the future.

Yep I agree! a bad battery...
I have had real good luck with the standard Red top Optima.

I've had my red top now for going on 6 years and still going strong!

A loose battery connection (or just a little corrosion between post and cable) will cause these symptoms. Alternator on it's way out (worn down brushes) or loose belt will cause weird trouble too.