Sorry if this is in the wrong sub-forum
MaineSail'sMaineSail'sMusing Sub is only for him to start new threads?
not really propulsion-specific but at 48V I guess here's best. . . (thanks mod)
I'd rather the discussion **please** not get derailed on the design-level "big picture", maybe in another thread; this is for a very specific issue I'm confused about. Note I am yes a noobie virgin on much electrickery basics, especially AC, and yes, I will at some point hire a pro "sparkie" to help assure safety #1.
I am looking to create a powerful high-current - but safe - charging setup on the cheap, and have decided to use 48Vdc "rectified" from shore / AC gensets,
to feed big loads like aircon, charging freezer eutectic holding plates, high-gph watermakers, and to charge the main LFP battery bank, ideally all at the same time, if / when the upstream power supply is sufficient.
Looking to start at 3kW, but higher would be better in future, also for use on an expedition truck rig, or an off-grid "shack", or perhaps for an EV / propulsion bank.
Using DC voltage conversion as needed, for e.g. normal House 12V distribution circuits, 24V bowthruster / windlasses etc.
Two source niche markets where such gear is **very** reasonably priced (even NOS!) are rack server power supplies from IBM/HP/Dell etc, and the telecoms industry.
With the latter, I am confused by their standard " -48Vdc " output (note the negative,) as opposed to the usual "regular" 48Vdc
I know in mobile use cases like cars and airplanes, no true Earth ground exists on either AC nor for DC circuits, and I "assume" the same is true on many / most / all boats, especially when charging is fed by a portable inverter generator.
Therefore, batteries' and consumer loads' negative return conductors are only all tied together to, here to be called "Vehicle Common", unless someone gives me a better term.
From googling, I read terms like
energized conductor (usually positive, "high side")
as opposed to the
current return path (negative / low side), and that
The power supply (charger / Rectifier's) output DC circuit may be completely Floating, aka disconnected from all the input AC circuits, or on the other hand, may be connected to Vehicle Common.
The input AC circuit Return conductor may or may not connect to Vehicle Common
The Rectifier's Chassis may or may not connect to Vehicle Common, and
finally, the Rectifier's internal components may be isolated from its own chassis?
I have seen people write the energized / positive output conductor from the Rectifier gets "grounded", i.e. connected to Vehicle Common, rather than its negative return, but I can't imagine that's right?
Is another device needed to change the -48Vdc output to "regular" 48Vdc? or
is it just a matter of carefully wiring things correctly for Ungrounded operations, using RCD / GFCI / ELCB protection and ground fault / leak detection gear to compensate?
MaineSail'sMaineSail'sMusing Sub is only for him to start new threads?
not really propulsion-specific but at 48V I guess here's best. . . (thanks mod)
I'd rather the discussion **please** not get derailed on the design-level "big picture", maybe in another thread; this is for a very specific issue I'm confused about. Note I am yes a noobie virgin on much electrickery basics, especially AC, and yes, I will at some point hire a pro "sparkie" to help assure safety #1.
I am looking to create a powerful high-current - but safe - charging setup on the cheap, and have decided to use 48Vdc "rectified" from shore / AC gensets,
to feed big loads like aircon, charging freezer eutectic holding plates, high-gph watermakers, and to charge the main LFP battery bank, ideally all at the same time, if / when the upstream power supply is sufficient.
Looking to start at 3kW, but higher would be better in future, also for use on an expedition truck rig, or an off-grid "shack", or perhaps for an EV / propulsion bank.
Using DC voltage conversion as needed, for e.g. normal House 12V distribution circuits, 24V bowthruster / windlasses etc.
Two source niche markets where such gear is **very** reasonably priced (even NOS!) are rack server power supplies from IBM/HP/Dell etc, and the telecoms industry.
With the latter, I am confused by their standard " -48Vdc " output (note the negative,) as opposed to the usual "regular" 48Vdc
I know in mobile use cases like cars and airplanes, no true Earth ground exists on either AC nor for DC circuits, and I "assume" the same is true on many / most / all boats, especially when charging is fed by a portable inverter generator.
Therefore, batteries' and consumer loads' negative return conductors are only all tied together to, here to be called "Vehicle Common", unless someone gives me a better term.
From googling, I read terms like
energized conductor (usually positive, "high side")
as opposed to the
current return path (negative / low side), and that
The power supply (charger / Rectifier's) output DC circuit may be completely Floating, aka disconnected from all the input AC circuits, or on the other hand, may be connected to Vehicle Common.
The input AC circuit Return conductor may or may not connect to Vehicle Common
The Rectifier's Chassis may or may not connect to Vehicle Common, and
finally, the Rectifier's internal components may be isolated from its own chassis?
I have seen people write the energized / positive output conductor from the Rectifier gets "grounded", i.e. connected to Vehicle Common, rather than its negative return, but I can't imagine that's right?
Is another device needed to change the -48Vdc output to "regular" 48Vdc? or
is it just a matter of carefully wiring things correctly for Ungrounded operations, using RCD / GFCI / ELCB protection and ground fault / leak detection gear to compensate?
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