This code would be cleaner if you did all the get() calls in advaance.

var healthy = this.lowbattery.get('healthy');   // etc.

And then, if you don't return right away, you can simplify it more.

```
var level = healthy;
if (value < low.level) 
  level = low;
if (value < verylow.level)
  level = verylow;
if (value < critical.level)
  level = critical;
return level;
```