I have an EZ Peak charger and cannot get my NiMH batteries to charge. Some batteries are brand new, some have not been used since last November and some were used in the last 5 weeks but another brand but still would not charge on the EZ Peak. They would charge for about 20-30 minutes or less then the charge light will turn green. I have unplugged the battery and plugged it again and same thing. Has this happened to anyone else? Is the charger bad?