My comments are based on how the converter Mfg intended the unit to be connected to the system
In actuality we are both correct.
A) The internal "red" wire (output of charger circuit) does get filtered by the battery for any loads that are connected off of that leg. [ie: Sensitive TV's and electronics.] The battery itself acts to smooth out the AC ripple.
B) The internal "blue" wire is an unfiltered output with AC ripple riding on it.
Please note: You DO NOT want to connect a battery directly to the "blue" wire circuit as it can create an excessive unregulated current flow (ie your 17.0VDC reading). This converter was not designed to be connected that way.
The output of the Full Wave Bridge rectifier (Diodes D1-D4) will energize the 2 relays and is then applied directly to the unfiltered output (internal blue wire). The battery should not effect this output. If either relay did not energize, then yes the battery will affect this output. The unfiltered blue wire output level is affected by the 120VAC input level. The blue wire output (no loads attached) should range from 12.5VDC (@ 115VAC) to 13.3VDC (@125AC).
The output of the Full Wave Bridge rectifier (Diodes D1-D4) is also applied to the charger printed circuit board (PCB). The PCB output (red wire) varies (12.0 - 14.1VDC) based on the charge state condition of the battery. (http://www.parallaxpower.com/6300/Li...sBatOvrChg.PDF