Hi, thanks for your question!!
Is this nuvi plugged into your vehicle or are you using this nuvi with its own battery?
The average battery life is about 3 hours for the internal battery between charges.
If you have the nuvi plugged into the car and it still will not power up please check the following things.
#1, Make sure all connections are tight
#2, Make sure the socket has power (socket the charger is plugged into)
#3, Check the fuse in the charger to see if its blown. (the tip should unscrew to house the fuse)
Please let me know what you find when you get the chance.
Looking forward to your reply, Charles