AngryPlum from my limited use of the device, it remains in pulse/repair mode until the nominal voltage is raised above 12.8v or there about. it then switches to charge mode until full (full displayed) after which it switches to trickle mode keeping the voltage somewhere between 12.8 and 13.6 (the recommended floating voltage, depending on temperature). the problem is with a damaged battery it will never reach 12.8 and will literally pulse it dry, even quicker with one or more dead cells.

AngryPlum in the standard charge mode this charger limits the voltage to 14.8v by current limiting. smaller capacity batteries have a lower internal resistance and will therefore reach the aforementioned voltage "easier/sooner" thus restricting the max current sooner. case in point charged a 14ah lead acid from near flat. max current never exceeded 2.2A. this is still too high for small batteries, causing accelerated evaporation so keep an eye on electrolyte levels. especially when using repair.