Computer battery life, and RAM memory choosing a new computer

Off the shelf retailer portable equipment battery life is given in how long the battery lasts from fully charged in hours. Manufactures have go ten into the habit of supplying some notes books batteries can't be replacement.
Unless a sales rep is familiar with the technical side of computer equipment they are at a loss at how many recharges computer batteries can take before they can't be recharged effectively any more. Electric bicycle batteries are said have a drive life of up to a 100 miles on one charge with a battery life of 5 years before needing replacement. You should enquire buying any protectable electronic equipment on the same on the same basis. With non replacement batter computers ask how many recharges before the computer can't be charged any more. Even enquire equipment batteries before they need replacement.
The most important information you should be well versed with when buying a new computer is on the bases of how much memory you require. This information is given by sales as a random access memory called RAM. It is not hard drive memory but temporary memory reserved  in the computer's mother board circuitry. Think of it as a flash drive memory stick memory when the power is on.
Drawing over the maximum the computer runs out of memory resorting to use the hard drive for compensation which is what makes your programs so slow in responding. Operating system have tools telling how RAM in use and how much is available.
In Windows 8 for example in the control panel click performance and information tools. The rate and improve your computer's performance page opens. Top right corner click advanced tools. The advanced tools page opens. Click open Task manager.  The task manager page opens. Click the performance tab. Click memory.

This page is a part of windows performance monitor of Microsoft's general Management Console (MMC). This page provides useful information on how much memory RAM you have in reserve.  In this page observe the bottom right corner in use and available. The term slots used is the number of RAM modulus slotted in the motherboard RAM slots.
You can monitor the memory drain in real time. You can customize the data you want to collect in logs, define thresholds for alerts in taxing RAM  and automatic actions, generate reports, and view past performance data in a variety of ways.