I replaced my battery after 1 year and 9 months, at 48K miles.
I noticed reduced power window speed with 3 to full AC blower speed when driving, and especially at idle at red lights. Also, the battery is unshielded from high engine bay heat. So, all these things considered early death of battery does not concern me. I bought a regular 3 year battery from Walmart, instead of paying premium for top of the line batteries or name brands.
The reason for that is I had top of the line Optima Yellow Top for my 2004 TJ, and it went dead before the warranty went out. I did get a full replacement for free from Sam's Club, but I will not pay premium $$ for batteries any more. I just plan to replace it every 2-3 years...
I bought and carry with me a Self-powered Portable Battery Jumper from Sam's Club. It's a self-contained battery with a short pair of jumper cables. With this, I have a piece of mind on Jeep trails in Moab or any other trails.
2009 JK Rubicon (Former Daily Driver); 2014 VW Jetta GLI Autobahn w NAV.
Auto, Power, Remote Start, Towing Package, MyGig Navigation with Lockpick, Rear View Camera, B&M 70268 Transmission Cooler, Aeroforce Interceptor, Valentine 1, Tub Sound-Deadened with Raamat and Ensolite, Hard Top Heat Insulated with 1/2" Styrofoam Insulation, Bilstein Shocks Front & Rear, PIAA Dual Horns, IPF 920H4 Headlights.
Protection: Skid Row Engine Skid, Lower Control Arm skid & Evaporator Skid; Rock Hard Gas Tank Skid; Warn Stainless Steel Differential Skid Front & Rear.
Recovery Gear: Warn 9.5Ti Winch, 11,000# Pull-Pal.
Communication: Uniden 520XL CB, Diesel External Speaker, 3' FireStik Whip.
Shrockworks Mid-width Front Bumper with Warn 9.5Ti Winch -- Ordered 7/17/2009; Bumper Received 12/4/2009.
1" Coil Spacer Front & 1/2" Coil Spacer Rear restored OEM Rake.
Moab - 4/2006, 5/2008, 4/2009, 5/2011, 4/2013
Ouray - 8/2007
Rubicon - 9/2008
Gone, but not forgotten: 2004 TJ, 1999 Audi A4, 1992 VW Jetta GL 5 Speed