2400 baud, 8 data bits, no pairity and "A=3.3, W=36.7" does not define how data is being sent, only a small subset of it. You need to see what comes out of the battery monitor in total before you can start taking it apart, programmatically.
Research (translation - Google) what Mike has said about software serial on the Uno and what I said about a USB to serial converter. Those are two of the key pieces you need in order to do what you've asked.
Here's a good assignment for you - draw a schematic of how you connect the battery monitor, the UNO and your PC together. Nothing fancy, paper and pencil will do. Then post a photo or a scan of what you've drawn.