Please get a volt meter and check your genset first.
208 is 3-phase in the US and is used in business and light commerce. 240 is split-phase household. Stay away from 480. That's
touch it and die voltage used in the US as an intermediate between the 21kv line on the pole to power bus stop and parking lot lighting.
220v is single line hot European voltage used in homes and light commerce.
3-phase can be Y or delta.
http://en.wikipedia.org/wiki/Three-phase_electric_powerIf your genset is over 5KW nameplate and has 2 hot wires then it supplies split-phase 240v for the usual US household connection. If your genset has 3 hot wires then it is 3-phase like the chargers you were looking at. 220v 3-phase is used for high current European appliances.
Big lift battery chargers for flooded cells are usually ferroresonant. If you do not supply the correct voltage and freq they will not charge correctly but may appear to be working. We had a lift charger at work with 208v connected to the charger's 240v lead. It would appear to charge and finish but the battery was still half-dead. We thought it was the battery until the service tech opened the charger cover to check connections.
European frequency is 50Hz. The US is 60Hz. That needs to match or you will have to derate the charger quite a bit.