Ok,I tested this but couldn't get it to work. Presumably I didn't follow the instructions properly.
When you do changes on HTML additional headers, you have to reload the browser. I hope you did this.
With some work it could be better, so for example, I lose the hover information, I had trouble getting two of these plots on one dashboard with different bins.
For hover information, I do nit get any clue. As I never worked directly with the D3 chart.
For the multiple of charts on same dashboard issue, you might have chart id issue.
Maybe because of this one,
@jkandasa I'm using the 0.0.3.Final-SNAPSHOT - does this mean I dont need to create a script like above but find a rule/condition about battery levels of nodes? If so, I cannot find that, but I am currently using your script example, which works, but is of course a little cumbersome compared to another option of using a node's battery level directly somewhere in the rules panel...