Does anyone use the rayovac 15 minute charger? I was using the european equivalent (varta) for a recording project in the caucasus (where I was happy about a few hours of electricity a day, so I really needed to charge quick), and the technique worked great, 4 aa batteries (2000mha) in 15 minutes. But I have the feeling that the batteries are getting very weak now, after just one and a half years - though I might have left them in the drawer to long... And the flaw is: it only works with the matching rayovac batteries