Charging according to UI characteristic curve:

Voltage and current are regulated, making “automatic” charging perfect for lead acid battery packs. Until reaching the preset end-of-charge voltage, current will be limited. After that, the charging current decreases continuously until there is only a trickle charge going into the battery. The charger can be permanently connected with no loss of power to the battery. This procedure is also referred to as parallel standby.

Charging according to IU0U characteristic curve:

This charging technique allows a battery to be charged safely and in a short period of time with current and 2-stage voltage control. The rechargeable battery is first charged to obtain a high voltage value (e.g. 14,5V at a 12V battery). If the battery achieves this value, the end-of-charge voltage will reduce to a lower and safer value (e.g. 13,8V at a 12V battery). The charger is now in the recharging phase.

Consequently, charging time is shorter but without overcharging your batteries. The charger can be permanently connected in order to keep the battery charged. In order to achieve careful charging of lead acid batteries you can set formation charging with a low charging current.

Parallel standby is also possible.