I have a 2012 JKU Sahara and when I got to start it on some days it will click like the battery is dead. The catch is if I leave the key in the on position for around 5-10 minutes then it will start, but it still starts hard. Any ideas? Thanks

 

Welcome to JKF.. Interesting condition.. 1st thought goes toward cables and connection..2nd a ground issue.. 3rd.. when was battery replaced; have not heard of a dead cell battery getting better with the key on and components energized. Post up your findings and solution as others could benefit.

 

Considering the "hard start" when it does turn over, I don't think you can rule out the starter that is 9 years old, but I would definitely look at all connections first. If battery is good and all connections look to be tight and in order, I'd test the starter.

 

Agree with the above. When you say "starts hard" do you mean it turned over and doesn't crank? Does it turn over fast or slow?

 

Batteries do come alive after leaving them on. Old trick up here in frozen north was to turn on the headlights for about a minute prior to starting. If you are parked out in the Michigan cold then this may be the issue. Try using the block heater but it does sound like a battery going kaputt to me.

 

+1 on that ^. I'd load test the battery and clean the terms.

 

Any follow-up troubleshooting your issue?