The BMV 700 installed on my narrow boat responds correctly when charging from solar power or shoreline/generator and shows correct volts,amps and watts. When charging from the engines 175amp alternator the volts read correctly at around 14.3 ish but the amps and watts stay in the negative, everything is wired correctly on the right side of the shunt so I'm a little lost although I do have a niggling feeling that the problem could be due to the earth connection linking to the engine starter battery which is obviously being charged at the same time from a separate alternator.
Can anyone confirm (or not) if this could be possible. Many thanks Eddie