horrible signal causes battery drained fast

Switching to Samsung S4 from an old model Samsung phone not long ago.However, compare to its cool new features, the battery life is not that favorable, even though I uninstalled those battery killer apps and disable sync on fb, mail,etc…I asked google and found out that the battery drains fast most probably because of the poor signal in the area I currently live. Much better in my house and the signal usually is full, but I am away from home most of the time so the time without full bar signal is usually 40-50%. That means if I want to preserve battery life in the day for longer talking time, I have to turn off all the cool new features that I upgraded a new phone for! Luckily the phone gives extended/swappable batteries options. Taking a secondary battery out with me would be acceptable. I was torn between a bigger one may be boosts up to 7000mah or a small one without any extra case, and finally picked up a MPJ one claims 3500mah cuz I think it cost effective after reseaching. Though I am not sure whether it has offered that much extra juice, it at least as good as the stock one. Below is a battery life graph of the extra battery while using at home on weekend, medium usage:some videos, google, web surfing, not a bad day! Cheers:-)