Power bank's basic function is to provide energy to charge the batteries in mobile devices such as smartphones / mobile phone. But today POWERBANK already equipped with many additional features. Here are some additional features.
Temperature Resistance
POWERBANK in his future will experience the heat when charged / dicas, when it serves as a charger and when stored. The heat comes from the energy lost in the process of change in voltage, both when filling the batteries in the POWERBANK, or when the battery is being emptied POWERBANK. The components in the POWERBANK must heat resistant.
Protection from short circuit
POWERBANK issued 5 volts for charging gadgets. But sometimes short circuit occurs because the pins on the charger cable is not accidentally connect briefly with a small metal, or it could be in the gadget short circuit occurs. If the short circuit is allowed, then a large current will flow, which can damage the POWERBANK, charger cables and gadgets. So if there is a short circuit resulting current is too large, then POWERBANK should immediately stop the flow. Even better if there is a short circuit indicator, so that the user can immediately know that there is a short circuit problem.
Mini USB connector that is commonly used for the charger. Difficult to create a short circuit, but who knows?
Source: http://pinouts.ru/PortableDevices/mini-USB_pinout.shtml
Reset Mechanism
POWERBANK can be disturbed so hang, or stop issuing short-circuit current due to no. To restore POWERBANK to operate the POWERBANK need to be reset to the initial condition.Input Overvoltage Protection
Protecting POWERBANK if the charger voltage exceeds the limit. Normally the charger voltage is 5 volts, but if there is damage to the charger, the voltage can exceed 5 volts and can damage the circuit in POWERBANK.Protection from output overcurrent
Outflow of POWERBANK must be limited, so as not to damage the circuits in POWERBANK. Overcurrent different from the short circuit / short circuit. Overcurrent can occur if the gadgets charged requesting large enough current, exceeding the limit of POWERBANK.
Output overvoltage protection
Maximum output voltage of 5 volts should POWERBANK. However POWERBANK output voltage can exceed normal limits if there is an interruption in the circuit in POWERBANK, so can damage the gadget. For that POWERBANK need to be safeguards so that if the output exceeds 5 volts then the output is disabled automatically, so gadgets charged no damage.Protection from overcharge and over-discharge
POWERBANK batteries can be damaged if you have over-charge / charge excess, ie fixed battery is full charged. Damage occurs generally because the incoming energy is converted into heat, and this heat can be damaging. On the other hand, Li-Ion batteries are often used in POWERBANK also be damaged if too empty, so there needs to be a series of deadly POWERBANK output if the batteries in the POWERBANK was almost empty.PTC Protective Circuit for the Cell
PTC (Positive Thermal Coefficient) is a device that can measure the temperature of the battery (cell). If the temperature is too high, then POWERBANK need to be turned off so that the battery and other components are not damaged.Here are examples of components PTC
Positive Thermal Coefficient of http://www.resistorguide.com/ptc-thermistor/
Some additional notes
Here are some safety factor to be considered at the time to charge the Li-Ion (source)- Cell polarity should not be reversed
- Temperature when charging should not be less than 0 ° C or exceeding 45 ° C.
- Charging current should not be too large, generally below 0.7 C. C is the capacity of the battery.
- Discharge current should not be too big.
- Charging voltage should not be too big
- Charging batteries should not be excessive, charging is stopped when the voltage exceeds 4.30 volts per cell.
- Discharging the battery should not be excessive, discharge should be stopped when the voltage per cell drops below 2.3 volts. Voltage per cell limit may vary depending on the manufacturer.
- Batteries may not work if the temperature exceeds 100 ° C.
Li-Ion battery charging quite complex, as can be seen in the picture below (source):
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| Graph of voltage and current charging Li-Ion battery. |
Voltage and current in charging Li-Ion batteries should be measured and controlled, so that the optimal charging and does not damage the battery. Read more about this subject in http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
