Keysight U1252B - Figure 5-4 Charging Mode; Figure 5-5 Charge End and Trickle State

5 Maintenance
136 Keysight U1251B and U1252B User’s and Service Guide
Figure 5-4 Charging mode
7 The charge end message (C–End) appears on the secondary display once
charging is completed. The trickle charging current is provided to maintain the
battery capacity. The flashing signs of and appear to show the trickle state.
8 Remove the DC adapter when the C–End message appears on the secondary
display. Do not turn the rotary switch before removing the adapter from the
terminals.
Figure 5-5 Charge end and trickle state