The ThinkPad Battery 40Y6797 battery from IBM-Lenovo is an extended capacity 9-cell rechargeable lithium ion battery with over-discharge protection that is also compatible with the ThinkPad External Battery Charger, available from IBM. Direct from IBM-Lenovo, this component comes with a one year limited customer carry-in exchange warranty which is pretty much the standard for accessory.

Compatible with a number of devices in the ThinkPad R60 and T60 line, this battery weighs in at just over a pound, and measures 0.8 x 8.9 x 3.1 inches. This battery does extend out from the rear of the machine farther than the original 6 Cell Battery pack, but it does not interfere with access to any ports. This component is however not compatible with the ThinkPad R61, R61i, and T61 14-inch Widescreen models.

As with any lithium ion battery, you can expect to get anywhere between 300 and 500 charge/discharge cycles from this battery, or approximately two to three years. These batteries perform best under partial discharges only, rather than fully emptying the battery before recharging it. However to avoid a condition known as “digital memory” which can cause your battery not to charge to its full potential, you should fully discharge and recharge the battery once every 30 cycles.

If you are purchasing this battery as a secondary power source, i.e. as a backup battery, it should be stored with a 40% charge, and switched with your main battery routinely. This will keep both your batteries in top working order. Also, be sure to keep any lithium batteries in dry, temperature controlled environments away from excessive heat or direct sunlight, as this can also impair the function of your batteries. This is a common issue that can arise when users leave their batteries in a hot car as well.

When able, it is best to remove the battery from your machine when fully charged and running on fixed power, such as that from your AC adapter. This helps air out the connections to prevent accumulation of dust or moisture in the battery casing, as well as preventing your battery from getting too hot in your machine.