My DC source (chrager) is 220 VDC, when measure + terminal to Ground, value is arond +110 VDC, Isn't it suppose to be +220VDC?
It will only be +220V DC if the charger has its negative output connected to ground.
There is no reason why this has to be so.  Many DC power supplies are isolated, with no connection between the output terminals and any of the input power terminals.