[happytiger]

Modern battery chargers seem to be fitted with moving coil meters,which are only correct on pure DC, older and more proffesional chargers are fitted with a moving iron meter which reads RMS,which I feel is more appropriate to work with.
If you measure the voltage with a MC meter it will read low ie 11.5v yet still charge a 12v battery. The limiting factor will be the peak voltage,and a large cap across the output will enable this to be read with a multimeter (set to DC) you dont want more than 14.7v for a fast charge or 13.8v for prolonged connection,(float condition.)
Another point, older battery chargers were often in excess of 16V,maybe to get around the extra drop with the metal rectifier,however these can ruin a battery if left connected after full charge.
The waveform makes little difference when the RMS figures are used.I have also found that lead acid cells have longer life when charged from a smooth DC supply,although some claims are made about pulse charging,(desulphaters) extensive testing does not confirm much useful results.