Perhaps one cannot just parallel generators willy-nilly.
From Honda:
EU2200i and EU2000i Parallel Operation
The EU2200i are only compatible with EU2000i or EU2000i Companion models within a specific serial number range:
EAAJ-2017305 through EAAJ-9999999
EACT-1000001 through EACT-9999999
Connecting an EU2200i with an EU2000i or EU2000i Companion that is not within the compatible serial range above may cause a low voltage output, which can damage tools and appliances powered by the generators. Units outside the compatible serial number range should only be paralleled with another EU2000i.
