I modified the MySensorsBattery device. The old device looked for names in existing devices. If you wanted a different name or you used a multidevice, pimatic couldn’t find a name so it would be empty.
I modified it this way that by default it still looks for an existing device to setup a name, you can override this by adding a name manually.
Once this update is released, your existing battery device must be modified. But pimatic will give you an error 
Example (new):
{
"id": "Battery",
"name": "Batterylevel",
"class": "MySensorsBattery",
"nodes": [
{
"nodeid": 11
},
{
"nodeid": 12
},
{
"name": "weatherstation",
"nodeid" 13
}
]
},