要获取 BLE 设备的电池电量，不一定非要使用 Gatt 协议。可以使用 GAP（Generic Access Profile）协议来获取设备的广播数据，然后从广播数据中提取出电池电量信息。

以下是一个使用 GAP 协议获取 BLE 设备电池电量的代码示例（使用 Python 语言）：

import bluepy.btle as btle

class BatteryDelegate(btle.DefaultDelegate):
    def __init__(self):
        btle.DefaultDelegate.__init__(self)

    def handleNotification(self, cHandle, data):
        battery_level = int(data[0])
        print("Battery Level: ", battery_level)

def get_battery_level(mac_address):
    peripheral = btle.Peripheral(mac_address)
    peripheral.withDelegate(BatteryDelegate())

    battery_service_uuid = btle.UUID(0x180F)
    battery_service = peripheral.getServiceByUUID(battery_service_uuid)

    battery_level_uuid = btle.UUID(0x2A19)
    battery_level = battery_service.getCharacteristics(battery_level_uuid)[0]
    battery_level_handle = battery_level.getHandle()

    ccc_uuid = btle.UUID(0x2902)
    ccc = battery_level.getDescriptors(ccc_uuid)[0]
    ccc.write(b"\x01\x00")

    peripheral.waitForNotifications(1)
    peripheral.disconnect()

# 使用示例
if __name__ == "__main__":
    mac_address = "00:11:22:33:44:55"  # 替换成你的 BLE 设备的 Mac 地址
    get_battery_level(mac_address)

注意，以上示例代码使用了 bluepy 库来与 BLE 设备进行通信，因此需要先安装该库。你可以通过 pip install bluepy 命令来安装。

此外，要成功获取 BLE 设备的电池电量信息，需要确保设备支持 GAP 广播电量信息，并且正确设置了电量信息的广播数据。