[DNK76]

Sorry but you do not know the microprocessor chargers,
is a current limiting example you set for 20A for 90Ah
At high discharge the voltage is lowered
but after some time it is set to 14.8V and is fixed at a low charge
battery life (generally 6-8 hours) the current decreases to about 15A, 10A but always has 14.8V or less depending on the brand charger generally 14.5V to 14.8V
  And as it drops to 4A then the charger will turn off to standby mode
13.8V and so can be connected for a year, good chargers for AGM can be plugged into the car without disconnecting from the installation
I like this study and I have always connected a voltmeter