Charging Methods and Battery Charger's-Electrostatic

Charging Methods and Battery Charger's-Electrostatic

List of Charging Schemes are given below:
The charger has three key functions as follows:

• Charging-Getting the charge into the battery 
• Stabilizing-Optimizing the charging rate 
• Terminating-Knowing when to stop

What is charging scheme? 
-Combination of the charging and termination methods is called Charging Scheme.

Charging-Termination:

When battery is fully charged, the charging current has to be dissipated somehow. The resultant is the generation of heat and gasses both of which are bad for batteries. The essence of good charging is be able to detect when the reconstitution of active chemicals is complete and to stop the charging process before any damage is done. while at all times maintaining the cell temperature within it's safe limits. Detecting this cut off point and terminating the charge is critical in Saving the battery life. In the simplest of chargers this is when predetermined upper voltage limit, often called the voltage termination  has been reached. This is particularly important for fast chargers where the danger of overcharging is greater.

Safe-Charging:
There is always a risk of over charging the battery, either in determining the cut off point or from abuse this will normally be accompanied by rise in temperature. Internally fault conditions within the battery or high temperatures can also take a battery beyond its safe operating temperature limit. Elevated temperatures accelerate the death of batteries and monitoring the cell temperature is a good way of detecting signs of trouble from a different causes. The temperature signal, or a reset table fuse can be used to turn off the charger when danger signs appear to avoid damaging of the battery.Additional safety precaution is important for high power batteries where the consequences of failure can be both serious and expensive.

Charging-Time:
During fast charging, it's possible to pump the electrical energy into the battery faster than the chemical process can react to it, with damaging results. The chemical action can not take place immediately and there will be a reaction incline in the bulk of the electrolyte between the electrodes with the electrolyte nearest to the electrodes being converted or "charged" before the electrolyte further away. This is perceptible noticeable in high capacity cells which contain a large volume of electrolyte.

fig 1.1:Charge transfer& time Interval

fig 1.2 :Charging Methods by Chemical Process