Battery voltage

I am running the 36V battery. When I have charged to full capacity and checking with a volt meter across pins 2 & 4 of the battery charging terminal I read 41.9 volts. When the control console read 50% and I read the voltage it reads 41.3 volts. Should the voltage reading drop to to 50% of what it read at full charge in correspondence to the console reading or should the voltage stay the same as it was at full charge? I hope you can understand my question !