Measuring Voltage from this battery can be a bit tricky. Along with a multimeter you will need something to short out the SHORTING PINS as seen in the first image.

Read voltage as seen in the Second Image. Do this by shorting together the Shorting pins and then reading the voltage from the Outer Pins with your multimeter
Read voltage as seen in the Third Image. Do this by taking a Voltage Reading from the Inner Pins with your multimeter.

The two readings should be the same and will be the accurate battery voltage reading. Refer to the table below depending on the type of your battery.

Battery Nominal Volts	Expected Voltage Readout Range
36V	35-42V
48V	44-54V
52V	46-58V

Debugging Battery & Charger