what is your advice for the best usage of the battery?

thanks a lot for your advice

I disagree with the Dell response. Leave the battery in all the time, as it gives you power outage protection. The battery SHOULD NOT be discharges completely UNLESS the projected use time becomes short or the charging circuity can not determine the charge state, and the circuity needs to be recalibrated.. Always check the battery state using the test buttons on the battery. 

It is not good to discharge the battery completely. Each time you do so, the projected use time will get smaller as will the total lifetime. Lithium ion batteries should not routinely be discharges below 20-35% of maximum charge if you desire a long life time. The new hybrid cars using Lithium batteries are not allowed to go below 35-50% charge, as they are required to last 100,000 miles. The Chevy Volt is at 35% because it uses a new modified battery structure which is more durable than the normal Lithium (which you have in your laptop) used in the Prius.

Hi KirkD

I appreciate the arguement. You are right when it comes to car batteries as they do require the power enough to start in the first place although its not entirely true when it comes to laptop batteries. There are various arguements when it comes to maintaining batteries. Well its alright in a Laptop battery to drain it below 20% atleast once in a while. I do agree with the fact that a Lithium battery need not be discharged completely thank you for pointing that out. Its not going to cause any problems if you do so, its just not a necessity when compared to NiCd batteries.

Just a correction, i think i did mention that the battery needs to be left in all the time. If not let me rephrase,  You can leave the battery in the computer for as long as you like. The battery's internal circuitry prevents the battery from overcharging.

Let me state its NOT a necessity to drain the battery completely, but to maintain a longer span the battery HAS to be drained to atleast 5% once a week.

People do have various theories, personally i do have a 9-cell Lithium-ion battery and decided to give it a try, have been discharging the battery atleast to 5-10% once atleast every 1-2weeks. Usually a 9Cell battery gives a backup of 6hrs, again that depends on the usage after 2.5yrs my battery lasts for atleast 5hrs.

PM me and i would be more than happy to discuss this further :), this topic is always open for discussion.

in the meantime do have a look at these

http://guides.macrumors.com/Laptop_Battery_Guide

Do I Need to Discharge the Battery in My Latitude LM to Prevent Battery Memory? - Dell Technical Tip - 132388

http://www.articlesbase.com/information-technology-articles/the-careful-maintenance-of-li-ion-laptop-battery-2418060.html

Telson

That was very useful.

Thanks again.

My reference to car batteries is NOT for startup, but for battery lifetime in hybrids. If deep discharging was OK, then why would the shutoff point be set so high; you could advertise longer run times if you allowed a complete discharge. I too, have experimented with periodic deep discharges with my M1530. Each time I did one, my projected battery life, using three different battery monitoring utilities, DECREASED. I have seen references to this effect more than once (however, can't put mt fingers on one now). My 6 cell battery is three years old, and has 70% of new capacity left. My wife's 9 cell died after 2.5 years, and she most always discharged below 10%.