A battery dictates how much amperage it will accept at the voltage at the battery terminals.
A charger rated at 1.5 amps, will only produce 1.5 amps, when the battery is still depleted and ther eis enough of a difference between the battery voltage and the max voltage the charging source will allow.
A 1.5 amp charger mught just be a maintainer and never allow voltage to go above 13.6v.
While a 95% charged battery might require 1.5 amps to be held at 14.5v, the same battery at the same state of charge, but at 13.6v, might only require 0.6 amps of that 1.5 amp maximum capability.
Each and every lead acid battery out there would prefer to be 100% charged, rather than anything less.
Actually achieving 100% state of charge, especially on an older battery, is not just a matter of hooking up the latest and greatest smart charger whose marketing department spent the most, but it is certainly better than leaving the alternator to do the task that it cannot, and will not. It is not allowed, by its voltage regulator, to produce enough amperage to hold the higher voltages for the duration needed to actually get the battery to a true 100%. Getting from 80% to 100% state of charge, takes no LEss than 3.5 hours, no matter how powerful the charging source might be.
Always recharge any Lead acid battery to as close as possible to 100%, for best battery longevity, and performance and reliability during that lifespan.
How many amps are flowing at the voltage at the battery terminals? If the voltage is higha nd the amps are low, the battery is nearly fully charged, if the vltage is still below the mid 14's and the amperage is still high, the battery is no where near fully charged.
Those with ultimate condfidence in their smart chrgers would be disappointed if they were to see how much amperage was still flowing when the charger reverted to float voltage, especially on an older battery unintentionally deeply discharged.
No ammeter to see how much amperage is flowing a the voltage at battery terminals, means one is blind and running on faith in the marketing department of their charger manufacturer.