I spent a few hours researching rechargable batteries and found that this brand seemed to be the best. The batteries are 2100mAh NiMH. They charge in an hour or two, then charge with a trickle effect to keep them full strength. I've left them in the charger for over a week and when I went to use them they were full. They have worked great on my digital camera and MP3 player. I've used them for a few months and will definately purchase more of this brand for the rest of my electronics. I also used the car adaptor a few times and it worked well for me.