I have a laptop Sony VAIO EA16 for 5 years. Now, its battery is weak and arrived to critical point but it works for about 1 hour. My problem is : when I pluggin my laptop it dos not turn on, It just works with the battery but the battery is not charged when my laptop is turn on. It just is charged when my laptop is turn of or sleep. Some times if I push the head of charger to socket in my laptop, it is charged. When it is charged the light releated to charging is in the flashing state some times and some times it is full light. What is the problem?Thanks!