When I start the jeep if it's cold the battery is low on the gauge and all the lights are dim and anything that uses power is either slow or won't work. When the jeep heats up it'll all the sudden kick over and be just fine..all systems normal..any ideas what could be causing it? Thxs

 

What is the outside temp that you describe as cold?
How old is the battery?

 

doesn't really matter on the outside temp..could be 40 degrees could be 90. It is just when I start it after it's sat for 8 hours or all night. Its about 3 years old.

 

The gauge reading low might be telling you something. I'd have the battery tested.
Is your starter covered in oil by chance?

 

I agree with Cruiser54. Get your battery "load tested". Any parts store can do this for you. I can't tell you how many 3 year old batteries I've seen fail, not uncommon at all.

Also get your charging system tested as that is critical to a healthy electrical system. A quick and dirty (but not comprehensive) test of your charging system can be done with a multimeter on DC volts. Place a lead on each post of the battery. At high idle, you should see approximately 14.4 volts give or take a bit.

While there could be other possibilities like a parasitic drain, etc it's simple stuff first and that is battery and charging system.

Good luck and keep us updated!

 

Could be as simple as the belt is slipping on the alternator, and it needs tightened? Have a look and see if the alternator pulley is spinning right after you start it.