This new replacement UNISYS 11J8639 laptop battery is 100% compatible with your 11J8639. Power-supplier.co.uk laptop batteries all come with a three years warranty and will meet or exceed the original 11J8639 specifications because they are manufactured for high performance in our factories using the best quality cells and most up to date safety and engineering control standards:

There are several steps you can take to insure that you get maximum performance from your UNISYS 11J8639 battery:

Breaking In New UNISYS 11J8639 Batteries - new batteries come in a discharged condition and must be fully charged before use. It is recommended that you fully charge and discharge your new battery two to four times to allow it to reach its maximum rated capacity.
Preventing the Memory Effect - Keep your UNISYS 11J8639 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 Your UNISYS 11J8639 Batteries 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 your portable device.
Exercise Your UNISYS 11J8639 Battery - Do not leave your battery dormant for long periods of time. We recommend using the battery at least once every two to three weeks. If a 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 battery for a month or more, we recommend storing 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 break them in before use.
For Notebook Users - To get maximum performance from your battery, fully optimize the notebook's power management features prior to use. Power management is a trade off: better power conservation in exchange for lesser computer performance. The power management system conserves battery power by setting the processor to run at a slower speed, dimming the screen, spinning down the hard drive when it's not in use and causing the machine to go into sleep mode when inactive. Your notebook user's guide will provide information relating to specific power management features.

Overview

Always on the go? No more worries for running out of battery power! You can back yourself up with this Ni-MH UNISYS 11J8639 Laptop Battery for your Laptop. Lithium-Ion batteries are longer lived than conventional batteries and do not require replacement as often. There is no battery memory effect with this Lithium-Ion battery — you can charge the battery whenever you like without fear of reducing its charge capacity. Moreover, you do not need to drain the battery completely before recharging it. This product has been tested on Power Supplier systems. It is supported by Power Supplier Support when used.