Code to allow changes to the display of an SVG image, based on the value of a variable being passed

I want to be able to take an SVG image (referenced directly from the stored location), and based on the outcome of a search be able to change features of that image. For example, a battery life indicator with an external boundary and internal bars. I want to run a search, get a 3 and "light up 3 bars" (example included) I need a piece of xml that will support this and allow a standard approach to uploading additional images. I'd also like to be able to easily pass numbers into the SVG image so that they can be easily rendered. See attached.