I bought a Victron power system supplied narrowboat and I have a problem between the input and output of my 12v input (starter battery) to 24v output (house battery) Buck Boost (BB) 50A DC DC Converter. Each time I connect the 12v BB input to my 12v starter battery, the 50A fuse blows. Not only that, even with nothing connected to the input of the BB, with the output of the BB connected to the 24V house battery, the input reads ~24V on the TSConfig software (and on multimeter). See image.
Is it possible that the ground connection to the buck boost should be isolated from the starter battery (as opposed to non-isolated)? I do have a Victron Smart Shunt but not sure if it is working properly. If the ground for the two batteries are linked directly, is it impossible for the BB to convert 12V to 24V? Logically I think the 24V house battery ground should be isolated from the 12V starter battery ground. Is that correct?
