The lead acid charger has an LED status indicator to inform the user of its status.  

Once the charger is attached to a sealed lead acid battery and plugged in, the charging process will begin. The charger will subject the lead acid battery to three steps of charging.

In the first step, the charger will enter into fast charge mode. During this step, the charger is in constant current mode with the current rate remaining at its maximum value.

In step two, the battery will be nominally 80-95% charged, and the charger will switch into constant voltage mode (current is no longer being provided at its maximum rate). The charger will continue to provide a constant voltage until the charge current decreases to the charge termination level.

The third and final step will place the charger in float charge mode, after charge full, remove the battery from the charger. If the float is needed for operational readiness, lower the charger voltage to about 13.8V/cell or 14.5V/cell, the chargers perform this function automatically, the float charge compensates for the self-discharge, the battery can be applied for an unlimited time, connect other battery, the charger can return to rapid charging (step 1)

lead acid battery chargers