The charging current of fast charge is large, so the charging time will be much shorter; The charging current of slow charge is small, so the charging time is long.
For example, if you buy a nickel-metal hydride charger, which is marked with output current of 1.5A, this is fast charging, because the current 5 nickel-metal hydride battery capacity is more than 2500mAh (2.5Ah), with 1.5A current charging, about two hours will be full; If the charger you buy is marked with output current of 100mA or 200mA, it is slow charging, and it will take about twenty or thirty hours to charge the 2500mAh battery, and it may not turn the lamp after full (the current is too small to detect). As for the damage of the fast charge to the battery, it theoretically exists, because the large current charging heat is large, and the chemical material composition in the battery has the possibility of accelerating the life consumption.
However, in order to save efficiency, this effect can generally be ignored (the battery cycle is generally 300-500 times, which can be used for so long is very energy-saving and emission reduction).
The principle is that the speed of the current varies per unit time. The so-called home AC slow charge, is on the basis of the existing residential power supply system (using single-phase 220V or three-phase 380V), the use of 5-10kW power level charger (in fact, it is an AC to DC, the output voltage is not necessarily low), converted into DC, the car battery charge. In this, the key is:
1, the use of electricity trough as much as possible, can reduce the impact on the grid, can also reduce the cost of users through the preferential price of peak and valley: this can be solved by timers.
2, the power can not be too large, charging speed does not need to be fast. Five to eight hours is enough. The capacity of residential lines should be considered. This charger, generally in the user here, can be placed on the car, can also be installed in the user's home.