The terminology used by by Amper time for suitable charge voltages is a strange mix of terms and confusing.
Convension for terminology for chargers developed for lead acid is for the three stages of the charge process.
The first stage where the majority of energy is forced into the battery is the bulk stage. The voltage at the battery during this period will be higher than the battery resting voltage and will rise as the state of charge increases.
The bulk stage will finish when the target voltage set in the charger is reached. This is termed the absorbtion voltage, some chargers based on Epever designs term this boost voltage.
Once the target voltage is reached the charger will hold this voltage constant for a predetermined time or until the charge current falls below a predetermined level. This is the absorption period where the the battery is 'topped up' to full. This period may be called boost duration. For lead batteries this absorbtion period ( boost duration) could be for a significant period, 2 to 8 hours. For lithium batteries this period for most applications can be short, less than 30 minutes. Idealy the absorbtion period should be terminated when the current falls to a predetermined level, some chargers have this feature.
Once the absorbtion period (boost duration) is over most chargers reduce the voltage to a float value, this is a lower voltage than the absorbtion voltage. Lead batteries need this to keep the battery fully charged, lithium batteries do not need this, as the self discharge is low. Since most chargers have a setting for float volts, for lithium using a value equal to the resting voltage is common practice.
Some lead batteries need an equalisation stage to maintain them in best condition. This an Infrequent period were a higher than normal 'target' voltage is applied. For lithium batteries this is not required . If the charger cannot be configured to delete this equalisation, then set the voltage equal to the absorbtion volts and period to zero .
The charge voltages recommended by many battery suppliers and manufactures are related to available chargers . Since all chargers are derived from lead acid chargers, the lithium manufactures have adopted similar charge voltages .
These charge voltages are not ideal and may cause system issues where the battery BMS shuts down the charge path due to high cell volts. Long term high charge voltages may damage the battery. ( this may help to sell more batteries!)
For any charger with a timer based charge termination these are the important values for lithium that determine charge.
For a 12v nominal battery.
Absorbtion volts boost volts = 14.0 or 14.2
Absorbtion period = 30 minutes
Float voltage = 13.4 to 13.6 ( use the higher value if solar is powering loads)
Solar chargers have a 'boost reconnect, or bulk reconnect' voltage, set this to 0.1 volt lower than float volts.
Equalisation set to disable or same as boost volts with zero period.
Temperature compensation set to disable.
Mike