If you consider the large percentage of office workers using DECT wireless office headsets, such as Plantronics Savi W700 series, a few tips on extending the life of your battery can pay off.  The following applies to rechargeable Lithium Ion Polymer (Li-Ion) batteries.

1. The biggest thing is heat. Heat will reduce headset battery life. If it gets hot every day, sits in front of a window, sits in a hot car, etc., this can negatively affect how long the battery will last. Store it at room temperature.
2. Completely discharging the battery continually will reduce its life. Believe it or not. It is happiest when it is re-charged at between 1/3 and 2/3 capacity.
3. Avoid discharging or leaving it discharged for extended periods of time. The battery loses the ability to hold a complete charge.
4. Since it is a lithium ion polymer battery, it does not develop a memory like Ni-cad batteries did. (With Ni-cad, if you typically charged it when it was still, say, 90% charged, it would eventually need to be recharged when it hit 90%.) It is perfectly OK to dock the headset when not on a call.
5. If storing for an extended period, discharge it to 40-50% charge. Lithium ion oxidizes at its highest rate if the battery is fully charged, which leads to quicker deterioration.

Plantronics Savi W710 wireless office headset has a rechargeable, replaceable battery

Savi W700 series DECT wireless headsets have a replaceable battery at the speaker including W710, W720, W740, and W745. W730 battery is not replaceable.