If you're dealing with one of the low-current chargers with a maximum output of 20-30 amps or so, a shorted battery will act like a dead short and overload it. I'm accustomed to using professional-type chargers capable of delivering 75-100 amps or so, with charging leads the size of 6 volt battery cables. They simply don't overheat, even at maximum current delivery.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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