So, a door left a bit ajar drained the battery on my '99 Jeep Cherokee XJ. We jumped it and drove it for a few days with no sign of trouble. Then, after a day of errands, we parked to wait for my grandson at school. When I went to turn the car back on, I got nothing but one lonely sounding 'tick'. Tried to jump it, but this time it wouldn't take. I've had no previous problems, other than electrical issues with my windows and stereo. Battery tested fully charged, so the alternator must have been working. Took the alternator in and it tested good, too. What else can we check?

 

Not to be funny but have you checked the battery terminal connections? How old is the battery? What do you mean by "tested fully charged"?

 

x2. I had to jiggle my ground wire and everything worked fine and when i got home, i realized the connection wires weren't completely connected

 

I pulled into a Sonic on day for a drink with my GC everything working fine and started to leave just a couple of groans. Call a friend ( store manager at AutoZone) for a jump he came and brought a battery also. Tried for 10 min to jump it just barley turned over, so he put the new battery in and we drove to the Zone and put it on a charger. It was a cheap battery and old besides being bad, knowing me he had brought an 84 mo. warranty battery for me when he came for the jump.

It can happen anywhere without warning.

 

When a battery is suspect it should be 'load tested'.
A bad battery can still read over 12 volts on a meter.

 

Do the lights and such still work? If so....


Check starter.