Battery is small. Only way to measure the charging system is with a volt meter. Across the battery while it is running. About 7 volts would indicate it is charging. Might take a few minutes to recharge after starting. Lots of current pulled from a battery that small. There has to be some sort of Tractor battery available even in Italy I would think. Pulling the negative from the battery won't hurt anything. You just removed the load from the circuit.
