I did two 8 day voltage tests on my 2018 Cadillac CTS. I used a battery tender to bring the battery up to full charge prior to each test – 12.96 volts.
I took my voltage readings using the under hood jumper terminals – the first test with the RA003 plugged in, and the second test with the RA003 removed.
The first day in each test, the battery voltage dropped to 12.65 volts.
Days 2 thru 8 in each test, battery voltage dropped by 0.02 volts each day. My conclusion is that with the ignition off on a 2018 Cadillac CTS, the RA003 (version 9.0) has little or no impact on the battery.