We recommend going straight to the battery, if at all possible. Try that first, if you are still having problems, proceed to check the items mentioned below.
If you turn your RF power down on the radio, does the problem still occur? Are you using the factory coax? Stray RF is causing issues with the gauges, and this can occur because of high SWR, or poor quality coax cable. If your SWR is low and you are using good quality coax, we recommend that you install a low pass filter inline with your radio and coax. There are many good models available, search Google for "Low Pass Filter" to find them.