Was charging 3 batteries (VTC6s) at 0.5A the other day, went to get them when it was time but found out they were far from being full. Then I noticed that the gage dropped to 0.25A. Checked the wall adapter (2.1A) and usb cable and still 0.25. Only when I disconnected and reconnected it, it jumped back to 0.5 Any idea why that happened? Batteries? charger? fluke?