Energup 18v Li-ion Rechargeable Power Tool Replacement Battery for Milwaukee Battery Type: Li-ion Voltage: 18V Capacity: 4000mAh Color: Black Prevent the Memory Effect - Keep the battery healthy by fully charging and then fully discharging it at least once every two to three weeks. Exceptions to the rule are Li-ion batteries which do not suffer from the memory effect. Keep the Power Tool Battery Clean - It's a good idea to clean dirty battery contacts with a cotton swab and alcohol. This helps maintain a good connection between the battery and the portable device. Exercise the Battery - Do not leave the battery dormant for long periods of time. We recommend using the battery at least once every two to three weeks. If a Power Tool Battery has not been used for a long period of time, perform the new battery break in procedure described above. Battery Storage - If you don't plan on using the Power Tool Battery for a month or more, store it in a clean, dry, cool place away from heat and metal objects. Ni-Cd, Ni-MH and Li-ion batteries will self-discharge during storage; remember to recharge the batteries before use.