If the charger is not indicating a full charge by displaying a constant light but blinks at a higher frequency after about an hour then the battery appears to not yet be fully charged. If you are only going by the four or five segment battery symbol on your camera's LCD anything over about 75% will usually show fully charged, since the first bar doesn't disappear until you're down to about 75%. If you leave the battery in the charger for several hours does the blinking eventually stop?

One thing I have noticed with "smart" (chipped) lithium ion type batteries is that when you charge them for the first few times after they have been on the shelf for an extended period they need to be charged and exhausted several times before they can be charged to full capacity. Leave the battery on the charger for several hours, then use it until it is down to between 10-15% and charge it for several hours again. repeat this cycle three or four times. This should help to condition the battery to accept a full charge.

If the battery has been left in the charger several hours, used until low, then charged again for a number of cycles and is still displaying the same behavior then one of three things is happening (listed in order of likelihood):

• The battery is defective and can't hold its rated capacity
• The charger is defective and isn't fully charging the battery to its rated capacity
• The camera is defective and is excessively draining the battery

If the charger and battery were included with the camera when new three months ago, then this is a warranty issue and you should pursue it with the appropriate Nikon Service Center for where the camera was purchased.

If you bought the charger and battery separately it is quite likely you were sold a counterfeit. There are probably more fake Canon and Nikon camera batteries in the marketplace than genuine ones. If you didn't buy them from an authorised Canon dealer you almost certainly purchased a fake.