Forrest, Thanks for this info. That makes sense as to what was happening to us (as described by Bill Prince).
The charge controller is a Midnite Solar KID and it has the warning you mentioned all over the manual (isolate negative in/out). We didnt realize the site monitor base share a common - We hooked the load up to pwr1 and the batteries to pwr2 to try and diagnose an earlier problem with the battery circuit breaker popping (with only pwr1 connected to load). As now expected it popped the breaker immediately. We disconnected pwr2 and increased the battery breaker from 20A to 30A breaker. No further problems since that change. -Rob On Wed, May 10, 2017 at 4:27 PM, Forrest Christian (List Account) < [email protected]> wrote: > On the base unit, the - side of both DC inputs are tied together. It is > designed that way, since it was designed to be powered from two positive > sources. > > If you are connecting two -48VDC busses to the base unit by connecting > 'common or return' to the + input on each, and the -48VDC bus to the - > input on each, the base unit will internally connect both of those buses. > As I described, this is by design because the unit was designed for + > voltages, not negative ones. > > The next iteration of the base unit will handle this much more gracefully. > I am not yet sure about whether the device will simply just support > either +48VDC or -48VDC, or if you'll have to select it in some way (at > ordering, with a jumper, etc....) > > > >
