Dear all, I started having some issues with the P2 batteries. They charge fine and work well until I reach about 45-50% charge when voltage drops to about 10.6V and I need to put almost full power to keep the phantom at the same altitude. The battery sign on fpv flashes as well. After a short while, the battery percentage drops fairly fast towards 0. Both batteries have started behaving that way after about 9 months ownership. Charging time is unchanged. Is that normal?