I was going over a request for a solar battery charger, and one of the points was a Low Voltage alarm (possibly meaning a LVD) to be triggered at -48VDC. This is a bit confusing as, to the best of my knowledge, most battery chargers and banks are rated at positive voltage such as +48VDC.
I know that +/- is mostly a matter of where you consider the ground to be, so does this mean that their battery bank is grounded at the positive pole? Or what is the usual way of connecting a battery bank of 48V to equipment that is working with -48V?
I am trying to figure out why they require a negative voltage for the LVD, basically.