Yeah, substitute it with a Cycleanalyst. Expensive tool, but worth every penny. Justin designed them to be used in the rain too.
You want the stand alone model. Simple to install, it goes into the wiring from the battery to the controller. It will give you waaaaay more good info that anything on a stock bike.
Once you post pics of the wiring, and better still if you can get a wiring diagram for it, we can help you figure out how to remove the crappy bike dashboard, and just wire the battery straight to the controller, with or without adding a CA.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.