Laptop Battery Chemistry 101 - Discount Laptop Batteries (Lithium Ion and Nickel Metal Hydride)1
All rechargeable discount laptop batteries create an electrochemical reaction that forces a stream of electrons from one place to another, then repeats the process once an external power source forces the electrons back to their starting point. In discount laptop batteries, the trick is to find an electrochemical reaction that provides the right mix of stability, safety, sustainability, physical size, weight, charge capacity, lifespan, environmental impact, and manufacturing cost.
For the laptop computer industry, two technologies stand head and shoulders above the rest: Lithium Ion (Li-Ion) and Nickel Metal Hydride (Ni-MH). First, we'll look at Li-Ion, which dominates the laptop battery marketplace at the moment.
In Li-Ion batteries, electrons move from Lithium Oxide to Graphite. Each Lithium Ion cell carries 3.6V, and anywhere from 6 to 12 are packed inside discount laptop batteries. Because of the way the cells are wired inside the laptop battery, the voltage is an even multiple of 3.6 - usually 10.8 or 14.4.
Lithium discount laptop batteries offer higher energy density than any other metal, and the chemical reaction carries no "memory effect", meaning that the laptop battery does not need to be fully discharged to maintain its peak level of recharge. In addition, Li-Ion discount laptop batteries experience lower levels of self-discharging compared to Ni-MH and other chemistries.
On the downside, the Li-Ion electrochemical reaction needs to monitored more closely than with other chemistries. In particular, all Li-Ion laptop batteries must have a microprocessor inside their case to control the charge and discharge rate, and to monitor the temperature and capacity status. This adds to the cost of the laptop battery and can make troubleshooting a faulty laptop battery more complicated. Fortunately, battery manufacturers have developed inexpensive and highly effective methods to ensure the safety of cheap laptop batteries.
Prior to Li-Ion, Ni-MH laptop batteries were the standard used by all notebook manufacturers. In a Ni-MH battery, the electrical current moves from Nickel oxy-hydroxide to a metal alloy, and the cells carry 1.2 Volts each.
Ni-MH was a vast improvement over its predecessor technology, Nickel Cadmium (Ni-Cd), because it suffers no memory effect, has a larger capacity, and was non-toxic to the environment. (Cadmium is a heavy metal.) On the down side, NiCd loses about 10% of its capacity within 1 day of being charged, and it has a much shorter lifespan than either Ni-Cd or Li-Ion.
For the most part, a laptop user has little choice in the matter of which laptop battery chemistry to choose. Some models are designed to accept either chemistry, but the notebook manufacturer must design this capability into their model in order for the user to have a choice. (In many cases, we carry both chemistries so that you have a choice.)