The original battery of N6230I cell phone is 970AH lithium battery. Nominal voltage of Lithium battery is 3.6V,full voltage is 4.2V. In fact, the standard rate of discharge (0.2C, C is the lithium battery capacity) lithium battery discharge plateau is generally at 3.7V. There is also a protection panel inside the lithium battery pack,whose main function is to prevent overcharge,over discharge and short circuit. Although battery marked can’t use metal to short-circuit the battery, it does not matter. Because the protection board will cut off the discharge circuit automatically.
For the chemical properties of lithium batteries, if over-discharge, the battery may be damaged, so need to design protection circuits to prevent excessive discharge. The general designed protection voltage of over-discharge is 2.4 – 2.6V. In the applications of cell phones, cell phones will have power management circuitry inside. The cell phone will show lack of electricity when detect the battery is depleted. In connect with voltage test, cell phone will shut down automatically before released. Lithium battery overcharging voltage set 4.35V, because IC value is more in this overcharging voltage. In fact, if the battery voltage charge to 4.25V is already a bit too filling, it is best to stop charging in 4.25V.
Charging process of Lithium battery charger is like this: First, detect the voltage voltage, if exceed 2V,it shows the battery has not completely lost discharge capacity, and began to charge in constant current . The standard charge rate is 0.2C, i.e. 970mAH of battery will charge with 194MA or 200MA current. Until 4.2V, then turn to constant voltage charging. The constant voltage is 4.2V. The current will be smaller and smaller, until the charge current is less than 0.01C, which is about 10mA. The instructions shows charge is full. At this point you can stop charging, or continue to charge, but the power will not increase too much. In fact, every time the battery is not completely depleted, there are nearly 30% of the electricity, so the charging time is generally 2 hours.
For this feature, we can do a simulation circuit to test the charger performance. We must first prepare a 1W-2W 100 ohm variable resistor(electronic market has, you can buy around 3 yuan), and then prepare a voltage meter. Set the midpoint of the resistor (C point in the figure) to 1/8 whole range from the B point(about 12.5 ohms),connect to the +- end of the charger (cell phone cases wholesale).
Measure the voltage of A and B by voltmeter, it should be around 2.5V, then adjust slowly C toward point A to gradually increase the resistance of adjustable resistor. While the voltage across AB should be increased slowly (in conditions, can measure the current of the charging circuit, the current should be constant. As mobile player merely has current meter. Lithium Battery (cell phone battery charger) is more sensitive to voltage.Here I say no more). When the voltage across AB reaches 4.23V or so it should not be increased. If the voltage still not stopped when up to 4.35V. Then it is not recommended to continue using the charger.because it is easy to over-charge,which is very damaging to the lithium battery. From: cell phone accessories