Over-charging protective device for rechargeable battery

Abstract

The invention discloses an over-charging protective device for a rechargeable battery, which comprises a detection circuit, a charge control circuit, a balance control circuit and a protection chip. Input ends of the detection circuit and the protection chip are respectively connected with the battery so as to detect a voltage of the battery and respectively output different detection signals. An input end of the charge control circuit is connected with an output end of the protection chip and carries out low-speed charging operation according to the corresponding detection signal. The balance control circuit is connected with an output end of the detection circuit and starts and carries out balanced charging operation according to the corresponding detection signal. By the over-charging protective device, the conversion from large-current high-speed charging to small-current low-speed charging of the battery is realized, meanwhile, the voltages and the capacities among a plurality of batteries are balanced, and the battery is prevented from being overcharged, so that the service life of the battery is prolonged and the safety and reliability of the battery are improved.

Description

technical field [0001] The invention relates to a control circuit for a rechargeable battery pack, in particular to an overcharge protection device for a rechargeable battery. Background technique [0002] Lithium-ion batteries, which are currently high-capacity rechargeable batteries, are ideal rechargeable batteries because they have no memory effect. When lithium-ion batteries are used in power products such as electronic products, motors or vehicles, it is often necessary to use multiple lithium-ion batteries in series to achieve the voltage required by the power products. For example, on a notebook computer, 3 to 4 lithium-ion batteries are usually connected in series to form a battery system of 11.1V or 14.8V. However, due to the differences in the voltage and electrical characteristics of the battery cells, there will inevitably be differences in the voltage and capacity of each battery in each group of series-connected batteries, and this difference will become larg...

AI Technical Summary

Problems solved by technology

Specifically, if it is found that the voltage of one of the cells is too high, the switch connected in parallel with the cell will be closed, and a part of the charging current will be bypassed through the corresponding resistor, thereby slowing down the charging speed of the cell.

[0005] This kind of passive balancing method can achieve a certain balancing effect, however, its excess energy (the excess energy stored in the high-voltage cell) is consumed in the form of heat energy through the balancing resistor, which is not effective, and it is easy to cause excessive balancing resistors. Heat generation, causing the battery to overheat during use, and the safety is not good

Images