I don't know why it did that but 2 amps is not going to overload a good battery maybe the charger got hot and shut down for it's own protection
if your battery is down by 100 amp hrs it would take 50 hours to charge it back to full
I would use a good 10amp smart charger
it chargers the way a battery likes/needs to be charged ..bulk charges till it hits 80% or so full then drops down
absorption till full charged
then float..to maintain ..
so I would hook up a different charger or meter and see what is going on