Verify Battery Voltage of a CB-Series Buoy
The battery voltage of a CB-Series data buoy can be measured using a DC volt/multimeter on the UW-6 (6-pin) SOLAR port on the data well top plate. This method works for both user-supplied battery systems with CB-PTL pass-through lid and NexSens-supplied CB-A01 and CB-A05 SLA battery systems.
Measure the voltage between pins 3 (V+) and 4 (GND) on the SOLAR port. Healthy SLA battery voltage is 12.0-14.9V.

Figure 1: UW-6 SOLAR port receptacle pinout for X2-CB data loggers and CB-PTL pass-through lids.
SLA batteries which have fallen below ~10V should be replaced, while batteries between 10-12V should be charged with a float charger or by connecting the buoy solar top and placing the buoy in the sun. Note that the system will be powered on when a cable is connected to the SOLAR port, and if batteries are charged during long-term storage, be sure to review the Data Buoy Storage Requirements.