I understand your concern with Battery Life on our latest 4G smartphone devices! These devices tend to use more battery power due to its web and application capabilities. I actually own a 4G device, and have had good performance out of my battery. I would like to include a link below that shows a video of tips and tricks for battery conservation for the 4G Samsung Droid Charge, just one 4G model device we offer:
Hope this answers your questions and addresses your concerns!