A Lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a PARTIAL charge rather than a FULL Discharge. Because of this, frequent full discharges should be AVOIDED as much as possible because it will lessen the life of the battery.
If the laptop will use the main power always, the battery inside will only last for 1-2yrs.
1. Try to keep the laptop battery at 40% charge in lower temperature.
I'm sure all of you will laugh at this, put it in a refrigerator if not in use at 40% charge. This is effective, I already tried it.
2. CONSIDER removing the laptop battery when running on AC power. Problem: transient due to power outage at blackouts. Solution: Use UPS, Uninterruptible Power Supply.
More than a year ago, I bought my Inspiron laptop, after 5-6months almost 18-20% of battery performance was decreased. When I read some research about Lithium-ion (BatteryUniversity.com). I tried to follow the recommended levels. Surprisingly, it reduces the aging of my battery. After one year, still the battery is in good condition. Here's the table they have published. A One-Year Performance Table.
This is all applicable to all Lithium-ion batteries.
I hope this helps!