I just bought a second battery for my Panasonic compact digital camera. It's a Lithium-ion battery. The charger that comes with the camera has a LED light on it. The light goes off when the battery has finished charging.

At the store where I bought the battery, the store clerk, who resembled a Radio Shack employee, warned me to be sure to charge my new battery for 12 to 14 hours.

He said that the charge that the battery currently contained (indicated by a 2/3 full meter when I plugged it into the camera, which the clerk said was a lie) was simply a "surface charge", whatever that means, and that the battery would need a full charge for best functionality. A small printed card that he slipped into the packaging repeated this same information.

Well, the little LED on the charger turned off after the battery spent only an hour in the charger. But the store clerk, and the printed card, both cautioned me that I should not pay attention to the little light on the charger; it would lie to me and the battery should remain in the charger for the full time period, regardless of the indicator light's state.

My argument is: The light indicates when the charger has stopped its function. In other words, once the light is out, leaving the battery in the charger is no different than leaving it sitting on the kitchen counter.

The store clerk says no, the battery is still being charged even when the light is out.

Who's right?