With just normal web browsing, your battery, when new should last for about 10 hours. After a year, the battery is rated to hold about 80% of its original capacity. Your battery is at about 40% of original capacity. Do you live close enough to an Apple Store to take your iPad in for a Genius Bar appointment? If a diagnostic shows an excessively depleted battery capacity and if your warranty hasn't expired, you'll be offered a free battery replacement. If it's out of warranty, the battery replacement cost is $99.00.