Hi everybody, i want to share some experience about battery lifetime which i made within 1.5 years observing 5 batteries. The most important: Do not store your batteries fully charged! This might be the most common mistake and reason for some painful lessons. Charge your battery to 100% only if you plan to lift up the same day. Store your batteries with 50% to 70% charge. Discharge down to 50% when you do not fly. There has been posted a lot about discharging. My solution: Buy a car charging board for Phantom batteries, like this or similar. Get 3 pieces halogen bulbs 12V 50W from hardware store. Solder the halogen bulbs together in parallel, attach a charger plug (female) so you can connect the setup to the charging board. The halogen bulbs will serve as load, consider 150W @ 12V ~ 12.5A. This is a good simulation of a real Phantom. Use AWG 12 or thicker wire. The discharger can bring your battery from 100% to 50% within 10 minutes. The setup is getting hot, think about cycling the connection after a minute or two. Hope this is useful. Fly safe!