Your converter is not working and the voltage is SO WRONG. Need to fix it or your good battery will be a bad one very soon.
If you check the circuit breaker and it is ON, then you can check the converter, wherever it is and look for external fuses on it. But in reality you may be better to replace it with a better one like a Progressive Dynamics unit of the same Amphours capacity as your current one.
If still under warranty then just take it back and have the dealer replace it.
2007 Chevy 2500HD Classic LBZ Duramax/Allison (Stock)
2005 Bigfoot 1500C8.2 AWESOME