I bought a 6000 mah battery from amazon. And I have to say it's awesome. Twice the juice.
I can go 2 days without charging. Did a little experiment. Started the day at 100%. At the end of the day, I was at around 76%.
http://imgur.com/EujBuoN ( pic at 10:30 ish)
Was home all day, so phone didn't get heavy use, but still I think 76% is impressive, way better than the stock battery.
Then, I went to rainymood.com and played the rain sound all night long. From 12:30am ish till 8 am. Battery in the morning was at 50%. Not bad again.
I'm pretty impressed with the battery, only thing is it's bulkier and you have to use a thicker cover ( came with battery). Usually, I play music all day long. When I'm at work and commuting. I think it drops to around 50% at the end of the day on heavy use.
Sorry for the formatting, on mobile. Don't know how to format correctly and also the dim screenshots, was using CF lumen.
Also, obviously it takes longer to charge.
Edit: link to battery on amazon http://www.amazon.com/gp/aw/d/B00TBBL896/ref=mp_s_a_1_1?qid=1451241943&sr=8-1&pi=SL75_QL70&keywords=lg+g3+6000mah+battery