The growing portable electronics products developed rechargeable battery capacity and cycle life performance such as the increasingly high demand. At present there are four commonly used categories, nickel-cadmium batteries and lead-acid maintenance-free batteries (referred to as SLA) in the last century, these two types of the sixties has been popularized, nickel-metal hydride batteries and lithium-ion batteries (including lithium polymer batteries) these two categories in the last decade, a large number of commercial use only. these four type of batteries have their own strengths, the following table gives the a basic reference, different battery manufacturers may have a greater difference between the specific values used to consult the manufacturer, for purposes of comparison data in the table for reference (table C for the nominal capacity of the battery unit for the AH (AH) , A said that constant current charging current.)
 

Comparison Program	Lead Acid Battery	Ni-Cd Battery(NICD)	Ni-Cd Battery(NIMH)	Lithium-ion battery(LI-ION)
Energy density(Wh/kg)	30	40	60	100
Cycle life(times)	300	800	500	800
Temperature (°C)	0~35	0~45	0~40	0~50
Max charger current    (A)	0.25C	2C	1C	1C
Charging	After the constant voltage constant current	Constant	Constant	After the constant voltage constant current
Charge Time (Hours)	C/A + 2 hours	C/A + 20%	C/A + 20%	C/A × 2

 

It certainly hope that the charger can charge in a short time to complete, but due to current is large and difficult to control, which in terms of cost and technology have a certain degree of price to pay. If conditions permit, use of about 10 ~ 14 hours charging end of the charger will be slow at night Filling low price, small size and so on.        For online and even the use of SLA batteries, charging method suggested the use of 2.27V / cell (corresponding to 12V battery 13.7V) constant-voltage charging, such programs will neither overcharge the battery, but also help stabilize voltage equipment. For and often off-line SLA battery charge and discharge using the occasion should be used first 0.2C constant current, then 2.45V / cell constant voltage, battery charge is getting better immediate access to 2.27V / cell constant pressure of the "three-stage" charging method. the whole charging time is about 8-10 hours.        NICD battery to allow a certain overcharge current, so the simple selection of 0.1C constant current source battery charger can be described as affordable.        NIMH batteries are more sensitive to overcharge, that the use of 0.1C current, if the charge more than 14 hours or that have rechargeable batteries and then continue to charge a good few hours on the battery life has a greater harm. Should charge their batteries Shutdown current time or reduced to 0.02C below the charge current is very important, even for the night-time slow-0.1C filling NIMH charger as well.        Maximum charge current to about 2C intelligent rapid charger has a lot of success stories. Such chargers usually have to be in the charge process can be closely monitored at all stages of the battery voltage, temperature and other parameters, when the battery is fully charged is about to automatically reduce the charge current when the magnification, this can be caused by over-charging the battery over-temperature to minimize the risk of over-voltage.        NICD and NIMH battery charging characteristics of two very similar, but NIMH battery charging process in heat some more, the peak voltage is even more obvious some. These two types of battery fast charging when they use one of several conditions following as a fast charge termination conditions: including the voltage rise slope (dV / dt), voltage of negative growth (-dV) and the battery temperature rise slope (dT / dt) . There are three conditions are set to protect under the conditions of abnormal movements: the maximum battery temperature, the maximum battery voltage and charger built-in timer. To achieve these monitoring and intelligent switching action, it must bring charger costs, but without these measures, the battery capacity will be faced with declining life cycle to reduce leakage and explosions and even security implications.        LI-ION and the SLA battery charging method is similar to, require the first constant current and then constant voltage, the difference is a lithium-ion batteries on the charging voltage of constant voltage phase of the precision is high ( "1%). As the safety of lithium batteries is a fatal risks, thus requiring the end of the charge control and protection should be particularly careful. For different applications, lithium-ion battery packs will be built there is a corresponding charge and discharge protection circuit in order to more secure than the protection of the battery does not occur.