In my old car with a regular plug-in charger, I could just plug the phone in and the charging would begin, enabling me to use the phone. It was not a Razr. Now that I have new 328 and new Razr, when my phone is getting really low battery, i put it in the cradle to charge. It doesn't work and my phone dies. Does the phone need to have certain amount of charge left in order for cradle charger to work? That would defeat the purpose, wouldn't it?