Get device battery level (zwave)

I would like to get the battery level of my zwave device weekly. But I couldn't find the exact command for this.

Here the JSON:

{
	"topic":"???",
	"payload": {
		"nodeid":4,
		"cmdclass":128
	}
}

which topic I have to use? I didn't found in OpenZWave::Manager...
cmdclass "128" = COMMAND_CLASS_BATTERY

Maybe anyone got the solution for this.
thx.