My small mains plug in 12v charger for lead acid batteries but puts out 18v, at supposedly 350ma but reads 1.9amps on my volt meter, fubu?

No, as the amps go up, the volts go down. If you put the appropriate load on it to draw 350ma, the voltage should be 18v. At 1.9 amps the voltage may drop to around 2v. You have a misunderstanding of what the power rating actually means.