I’m looking to have full understanding of the actual charging efficiency of the MPII. I understanding the efficiency of the BMS however there are additional variables needing identification. On average, the VRM dashboard shows 1,600 watts coming from shore power per the MPII, and 1,300 watts going to the batteries per the SmartShunt representing 81% charging efficiency. The specifications for this devices present an efficiency of 94%. What changes are needed to achieve peak charging efficiency.
You will find that the 94% is the maximum efficiency and this is clearly stated on the datasheet. The charging efficiency is not quoted. Maximum efficiency is achieved at low power. As an example, the link below shows the curve for the inverting function of a 3000VA Multiplus and the charger will broadly follow a similar shape. This follows from the basic physics of power loss increasing disproportionately at higher throughput plus the impact of self consumption being seen at low throughput. It is always more efficient to charge at lower rates. Other factors such as the input ac waveform, equipment temperature etc. will also have an impact.
