Fully Charge RT

[J515OP]

I'm pretty sure the source is good. They simply state that "polymer" has been used as hype (which it has). Of course these conversations have a way of taking on their own life just like oil, you will get people that passionately argue that the "old rules of thumb" still prevail. Of course on both topics there is plenty of information out there.

This type has technologically evolved from lithium-ion batteries. The primary difference is that the lithium-salt electrolyte is not held in an organic solvent but in a solid polymer composite such as polyethylene oxide or polyacrylonitrile. The advantages of Li-ion polymer over the lithium-ion design include ″potentially″ lower cost of manufacture,[citation needed] adaptability to a wide variety of packaging shapes, reliability, and ruggedness, with the disadvantage of holding less charge. Lithium-ion polymer batteries started appearing in consumer electronics around 1995.

Risks and limitations

Overcharging a Li-poly battery can cause an explosion or fire.

During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 V per cell (used in a series combination), or else the battery will subsequently no longer accept a full charge and may experience problems holding voltage under load. Li-poly batteries can be protected by circuitry that prevents over-charge and deep-discharge.

Compared to the lithium-ion battery, Li-poly has a greater life cycle degradation rate.

Lithium polymer-specific chargers are required in order to avoid fire and explosion.

Explosions can also occur if the battery is short-circuited, as tremendous current passes through the cell in an instant.

Charging

LiPoly batteries must be charged carefully. The basic process is to charge at constant current until each cell reaches 4.2 V; the charger must then gradually reduce the charge current while holding the cell voltage at 4.2 V until the charge current has dropped to a small percentage of the initial charge rate, at which point the battery is considered fully charged. Some manufacturers specify 2%, others 3%, but other values are also possible. The difference in achieved capacity is minute.

Storage

Unlike certain other types of batteries, lithium polymer batteries can be stored for one or two months without significantly losing charge. They also prefer to be stored around 40-65% charge (i.e.: 3.75~3.90 V/cell).[citation needed]

Source: Lithium polymer battery - Wikipedia, the free encyclopedia

Lithium polymer batteries are an adaptation of the familiar lithium-ion batteries used in laptop computers and other devices. However, "lipo" batteries, as they are often called, are encased in a flexible polymer casing, making them lighter and suitable for use in small devices like cellphones. It's critical to use the proper method to charge a lithium polymer battery, since overcharging can cause a fire or even an explosion.

Purchase a battery charger specifically designed for lithium-ion batteries. Whether it's a regular or a polymer type, a lithium battery has a characteristic voltage drop when it reaches full charge. Lithium battery chargers have a sensor built in that detects this voltage drop and terminates the charging process, preventing a dangerous overcharge. You can purchase lithium battery chargers starting at about $20 at most electronics stores (price as of 2010).

Tips & Warnings
Lipo batteries have an internal sensor that measures the amount of stored energy available. However, this sensor becomes inaccurate over time. About once a month, use the battery until it is completely discharged and then charge it to 100 percent capacity. This resets the internal sensor. The device using the battery will then get correct data and provide you with an accurate estimate of remaining charge, thereby avoiding unexpected shutdowns.

If you need to store a lipo battery for long periods, charge or discharge it to 40 percent capacity. This will prevent stored batteries from degrading and will maximize their useful life.

Source: The Method to Charge a Lithium Polymer Battery | eHow.com

That is a total of 3 separate sources all with virtually the same information. The bottom line is that devices are smart enough to take care of themselves and no special care is required by the user under normal circumstances.

If you start trying to defeat the charging circuits or plan on storing a devices for months then you may want to use some of the tips mentioned.

 

[thix84]

thank you Arnold and J5250P.. your information are all helpful theoretically But for the sake of all Surface user knowing that the charger and device doesn't have capabilities on disabling when it is already full charge and shutting down when battery is low.. (like on modern laptops), what it the ideal way to keep our battery last for long?

 

[Romp]

Lithium ion chemistry prefers partial discharge to deep discharge, so it's best to avoid taking the battery all the way down to zero. Since lithium-ion chemistry does not have a "memory", you do not harm the battery pack with a partial discharge. If the voltage of a lithium-ion cell drops below a certain level, it's ruined.

HowStuffWorks "Lithium-ion Battery Life and Death"

 

[J515OP]

thank you Arnold and J5250P.. your information are all helpful theoretically But for the sake of all Surface user knowing that the charger and device doesn't have capabilities on disabling when it is already full charge and shutting down when battery is low.. (like on modern laptops), what it the ideal way to keep our battery last for long?

The Surface and all modern devices do have the disable charge feature built into them. They have to for safety reasons. It also turns off when the battery is low just like a laptop.

If they didn't the batteries would swell and catch fire under continuous charge. This will only happen if you defeat the protective circuit or clip direct power to the battery leads or something else not intended. Otherwise you might only run into issues with devices that are not regulated like Chinese knock offs or on rare occasions manufacture defects (which you can't control). There is nothing you need to do to keep your battery lasting a long time except perhaps avoid deep cycling it on a regular basis. That means do not run the battery all the way down every time before your recharge it.