I have the Meccer Kool Energy 1000W 50 AH loose standing unit. It had the same charging problem of dropping 2% after every charge. I sent it back to be repaired. They said it needed a software update. I got it back and it was working fine for a week, but it discharges too fast now. Even with nothing plugged in, the battery will drop 10% after 30min. Likewise, when I charge it, it charges really fast (40% in less than 10min).