1970s dodge colt keeps frying battery you can see the acid coming out the battery
1970s dodge colt keeps frying battery you can see the acid coming out the battery
That means the alternator is overcharging the battery, and it's an explosion hazard. Get a multimeter, set it to volts DC and test the battery with the engine running. If it's more than 14.5 volts and it's cold outside, the alternator is toast.
Too high a voltage from your alternator, as @justin-shepherd said. Not only is it frying your battery but if not fixed it may burn out your instruments. If the voltage regulator is separate from the alternator you can probably just replace that. Or, the regulator may be bolted on the alternator and easily replaceable as it is on some Bosch alternators.
As you are proably aware the Colt actually a rebadged Mitsubishi. You didn't state the exact year or engine, but per the rockauto.com database for a 1974 Colt with 1.6 engine there is a separate voltage regulator and judging by appearance it appears to be the old electromechanical type. Those are adjustable but if you have the original 50-year-old regulator probably best to replace it. (This regulator is listed to fit 1971-1979 models.)
