BQ77915均衡问题

user5379718

Prodigy 100 points

Other Parts Discussed in Thread: BQ77915

使用BQ77915给5节18650电池座保护均衡，其中CBI通过0ohm电阻连接到VSS。在充电过程总，有一节电池达到4.2V后CHG悔断开充电回路，均衡电路却没有起作用。

另外咋数据手册中，很多参数是可选的（例如tOVn_DELAY），但实际中没有给出如何设置改参数。

6 年多前

0 Star Xu 6 年多前

TI__Guru*** 130456 points

这个是正常现象, 充电过程中其中一串达到条件就会停止充电. 您可以多跑几个充电cycle观察均衡情况.
参数可选是在工厂端设置的, 客户无法手动修改.

0 user5379718 6 年多前回复 Star Xu

Prodigy 100 points

您好，谢谢解答。
测量中发现5节电池只有一节达到4.2V，其余的只有3.8V左右，根据数据手册描述，此时应该是cell balancing FET开始工作，为什么均衡FET为工作而充电FET工作，这样的话均衡功能就没有其作用吧？
9.3.4 Cell Balancing
Cell balancing is performed by comparing the cell voltages with respect to cell balancing threshold voltages,
evaluating the results of the comparison and controlling the cell balancing FET, which over a period of time will
allow for closer cell voltages, thereby extending battery pack life. The conditions for performing cell balancing
are: CBI is connected to VSS, no device in the stack is in a fault condition, and the pack is charging
CBI is the cell balancing input pin. It enables cell balancing function for the device.
• Leave the CBI pin floating to disable cell balancing. An internal circuit pulls up the CBI pin to AVDD in this
case.
• Connect CBI to VSS to enable cell balancing.
In a single device, cell balancing of all the odd numbered