Thursday, April 15, 2010

''Discharge the battery fully before re-charge'' Again ''Do NOT fully discharge before re-charge, for battery will be ruined''

Confusion is the rule of the game,  for poor me,  where batteries are concerned.

 Am told,  ''Discharge the battery completely before re-charge,  for longer life.''
Yet again am told,  ''Do NOT completely discharge battery before re-charge,  for battery will be ruined''.

Is this strange phenomenon applies only to me --  an old man among modern-day-electronic-geeks ?

Or is confusion common but kept smothered inside,  for fear of behind-the-back-ridicule ?

Now we find both maxims are correct,  only applies to different batteries.

Rest of this posting will only interest uninitiated old people who were suddenly introduced to new novel gadgets by their loved ones.

So,  modern geeks please remove yourself. 

The basic idea behind the rechargeable battery is simple: when electrical energy is applied to the battery, the electron flow from negative to positive that occurs during discharge is reversed and power is restored.

Basically there are,  commonly,  two kinds of batteries we happen to use.

One,  Nickel--Cadmium rechargeable batteries.   Two,  Lithium-ion battery.

Fully discharge the Nickel--Cadmium battery before recharge.

Lithium battery will be ruined if discharged fully.

There it is clearly stated,  for the non--geeks only please,  what is what in general on ''Rechargeable Batteries''.

Now let us,  non--geeks,  see  'what is what in this and that',   just as good old நாய் நடேசன், would have put it. 

Nickel-cadmium rechargeable batteries have the ''memory effect''.  

When battery recharged before it has discharged more than 50 percent of its power,  it forgets that it could fully discharge and recharge to the maximum.

And when it forgets its maximum potential it will naturally function just below the 50 percent of its power.

 Memory effect is caused by the formation of hard-to-dissolve cadmium crystals deep within the battery.

Cadmium crystals are an unavoidable by-product of discharge; the trick is to keep them small enough to be reformed as cadmium during the charging process.

When a battery is not fully discharged, the crystals deep within the battery are not affected by the influx of electrical current, so they are not reformed as cadmium and can grow into the troublesome larger cadmium crystals.

The battery will still function normally, but is maxed out at 50 percent.

The memory effect can be avoided by fully discharging the battery once every two to three weeks.

Allow it to discharge completely, and then fully recharge.

It's important to remember that no battery, rechargeable or otherwise, will last forever.

All batteries suffer from aging cells --  just we old fogies do. 

Lithium-ion batteries start degrading as soon as they leave the factory.

They will only last two or three years from the date of manufacture whether you use them or not.

If you completely discharge a lithium-ion battery, it is ruined.

Lithium-ion Cells have an outer case made of metal which is pressurized and has pressure-sensitive vent hole.
If the battery ever gets so hot that it risks exploding from over-pressure, this vent will release the extra pressure.
The battery will probably be useless afterward.

Lithium-ion batteries age. They only last two to three years, even if they are sitting on a shelf unused.

Battery University is an on-line resource that provides practical battery knowledge for engineers, educators, students and battery users  battery choices and ways to make your battery last longer.

 Read full articles here.

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