Lithium (ion) Battery
The application, the design, and charging and discharging.
Li-ion batteries are mostly used in today's technology and are being used in laptops, PDAs, cell phones, and IPods. The popularity of the batteries is simply because it is the most energetic rechargeable batteries available. You must be cautious in using Li-ion batteries, for they can burst into flames occasionally. Though the probability of these batteries to burst into flames is three in a million, the danger still exists, and when that happens it goes to extremes. Li-ion batteries have been known to fail in masses, and when that happens all the batteries are called back world-wide.
In view of all these, the question is what makes these batteries so energetic and so popular and what makes these batteries burst into flames?
As regards the popularity of Li-ion batteries, they have some specific advantages, which make this battery so competitive. Li-ion batteries are much lighter and have comparatively smaller size compared to other batteries. The electrodes of the battery are made of lightweight lithium and carbon. Lithium being a highly reactive element, huge energy could be stored in its atomic bonds, which provides the Li-ion battery with high energy density. For example a Li-ion battery stores up to 150 watt-hours per Kg, although 60 to 70 watt-hours might be more typical. On the other hand, a lead-acetate battery stores up to 25 watt-hours per Kg. This type of batteries, built with lead-acetate design, takes 6 Kgs to store the same energy as that of a 1 Kg Li-ion battery.
Li-ion batteries lose about 5% of their charge per month if not used after full charging. Compared to this a NiMH battery loses 20% of its charge in the same period. The batteries do not have any memory effect. This means that you do not need to deplete the battery completely before re-charging. Li-ion batteries can withstand several charge and discharge cycles.
But these batteries are not flawless, and have their disadvantages also. The most notable disadvantage is that, the battery starts to degrade as soon as it leaves the factory. The life-time of these batteries is between 2 to 3 years, whether you use it or not. Li-ion batteries are extremely sensitive to high temperatures, and they degrade faster in high temperature environment. Li-ion battery should not be discharged completely, and if you do that it will get completely ruined. It requires an on-board computer to manage the battery pack, and this makes a Li-ion battery to be more expensive than the others.
Li-ion batteries come in various shapes and sizes. However they look all the same inside. Though you should not take apart a Li-ion battery, if you happen to have a look inside, you would find the Lithium cells to be of cylindrical shape, and looks very much like the AA cells. The cells could also look like prisms. The on-board computer would comprise of:
- One or more temperature sensors to monitor the battery temperature.
- A voltage converter and regulator circuit to maintain safe levels of voltage and current.
- A shielded notebook connector that lets power and information flow in and out of the battery pack.
- A voltage tap, which monitors the energy capacity of individual cells in the battery pack.
- A battery charge state monitor, which is a small computer that handles the whole charging process to make sure the batteries charge as quickly and fully as possible.
As you charge your Li-ion battery, the battery may get heated up and the computer shuts down the current flow to cool down the battery. Same way, if you leave your laptop in your car in a extremely hot weather, the laptop would not switch on, and would only do so after it has cooled down to a specified temperature. If you have completely depleted the cells of your Li-ion battery, your battery might have got damaged and would not re-charge.
|
|
|
Recommended
Battery Stores:
|
|
|
|
