To better use your acer extensa 501 series battery, please take care of the precautions listed below :
1. The simplest and most obvious way of getting the maximum life out of a battery is to ensure that it always works well within its designed operating limits. There are however some further actions which can be taken to increase the battery life.

2. Do not modify or disassemble acer extensa 501 series battery, as the materials inside may be toxic and may damage skin and clothes.

3. Do not attempt to short circuit the terminals or store your battery pack with metal objects such as aglet. Doing so can damage the product and generate heat that can cause burnout. Also, caution must be given to prevent accidental short-circuiting of the battery.

4. Do not incinerate or expose battery to excessive heat, which may cause the battery to rupture. Also avoid placing batteries in water or other moist device, as this may cause the battery to fail.

5. Never solder anything directly to a battery. This can destroy the safety features of the battery by damaging the safety vent inside the cap. Permanent connections to an energy cell may be made by spot welding solder tags to the terminals. A soldered connection can subsequently be made to the tag.

6. Never insert a battery with the positive and negative poles reversed as this can cause permanent damage to the battery which may swell or rupture.

7. Never charge with an unspecified charger or specified charger that has been modified. This can cause breakdown of the battery or swelling and rupturing.Never attempt to charge a battery which has been physically damaged.

8. Never reverse charge or overcharge with high currents (i.e. higher than rated). Doing so causes rapid gas generation and increased gas pressure, thus causing batteries to swell or rupture. Don't leave the battery in the charger once it is fully charged.

9. Do not pierce, hit, step on, crush or abuse acer extensa 501 series battery.

10. Store the batteries in a cool place and when in use don't allow them to remain in environments which may be subject to overheating.

11. Batteries should always be charged prior to use. Be sure to charge correctly.