Lead acid batteries will charge at 75 amps. They'll just get warm, and this will not necessarily hurt them unless they get too warm. However, to charge this fast they need to be discharged to some degree to accept it.
The charging system in our cars is archaic (as it is in most vehicles). The voltage regulator puts out X voltage and lets whatever current will flow go. If the battery is at 11V it'll charge a LOT faster than if its at 12.5V (which is nearly full).
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View my fuel log 2015 Mirage DE 1.2 manual: 47.2 mpg (US) ... 20.1 km/L ... 5.0 L/100 km ... 56.7 mpg (Imp)