One of the most important aspects of proper selection of laptop and rechargeable batteries is to check them when buying. Demand that the laptop is unpacked in your presence. This will avoid purchasing goods from the shop window. But they often are much less.
Make sure that all the separate elements - rechargeable battery and AC charger - packaged in individual packets. Turn on your laptop and charge it until the moment when the indicator shows 99%.
Due to the fact that the batteries laptops use lithium ions, they have a "memory effect" similar to a phone battery. To achieve maximum capacity of the battery, it must fully charge and discharge three or four times.
The battery battery laptop a certain resource. To vain not to spend, recommend as little as possible to use the battery. Ie if you often use the laptop at home, the battery is better off.
In any case, do not remove a fully charged or depleted battery for a long time. Recommended to charge it to 50-60%. Wrap it in a thick plastic bag (you can use the one in which it was at purchase) and store in a cool, dark space (even in the fridge but not the freezer).
Note that when you use the laptop without the battery battery, best to plug it in through a surge protector. Do not disconnect the battery from the laptop for a long time. About once a month plug it in and do a cycle charge-discharge.
If possible, purchase a second battery simultaneously with the purchase of the laptop. This will allow you in future to save nerves and money.