The original firmware come with this tab plus is defective, I think. when wifi on all yahoo push mail and viber service is running on background, it drains 50% of battery in 10 hours sleep mode. after flash the new firmware, same wifi on and push mail, viber, it drains 20% of battery in 10 hours sleep mode, even it is better, but I think this still defective, it should drains less than 10% of battery in 10 hours sleep mode!
consider it is 4,000 mAh, 20% of it should be 800 mAh, it is half of all small screen smartphone's battery, this means smaller screen smartphone in sleep mode, when wifi on and push mail and viber service running, it might consume 50% of the battery in 10 hours, that is bad, it is still defective.
Samsung should look at this and find out what is going on! Hope upgrade to Ice Cream
Sandwich will solve this problem.