Flexible charger setup 24/48Vdc / 100-240Vac, 2200+W

Reco's requested, requirements in priority order, fantasy "ideally"s at the bottom.

Top quality regulated stable voltage DC output from possibly dirty mains input,

Capable of running safely in an off-grid no-true-ground context like marine- or wheeled-vehicle-based generators. Ground may simply not be available, even a 2m rod into dry desert earth is not great. Middle of the Great Lakes dunno, not a sparkie, would rather a design assuming no true Earthing available.

Safety features, to be operated by noob idjits (even more so than me), so use of ground leakage circuit breakers, ELCB's, or residual current devices, RCD's, etc?

Reliability, long-term heavy use in the field.

2200W continuous output, or close anyway.

Between 35V minimum and max is 49V

Sometimes only 10A USA 110V available, sometimes 220/240 up to 3-phase industrial whatever that means. Ideally worldwide compatible, include Euro, S.America, Japan.

Really ideally could power from two separate gennies or 10A 110 circuits. Willing to go to two separate 1100+W PSUs paralleled or in series to get this?

The output could be 24V nominal, if series'd able to get to 48V. Apparently only 2 in series is the limit, not true for paralleling?

Or ideally just one big unit can be fed from 2 separate AC sources, which can get to 55.2V, but is adjustable down to get to 49V, and/or even 13.8 / 27.6 as well (4s/8s/16s LFP)

But willing to use DC-DC buck boost conversion to get to those low ones if necessary.

Compact, cool and quiet as possible would be nice.

As would cheap!

Have so far come across:
ELTEK Flatpack2 (some only 2000W?)
Cherokee CAR2548
ES120
Mean Well RSPs
Eaton APR

Fallback plan is a couple of "IBM 835W" PSUs series'd, plus also carrying an ESP120 as well 8-( , a kludge I'd really rather avoid.

3 configurations depending on upstream available:

A. One 835W PSU on its own, converter-boosted up to 13.8V output @60.5A, will run off 110AC pulling under 8A.

B. A pair in series @24V native, converter-boosted to 27.6V, same 60.5A, runs off a "normal" 15A 110AC circuit if you carefully limit current drawn.

If 2 series'd for 24V really is the limit,

C. To get up over 2200W, carry a separate HP ESP120, for use off 220/240 only.

All are world power compatible, 50/60Hz

Plus, each source can be used for day-to-day charging of assembled LFP banks on its own, 

A for 4S, B for 8S, C for 16S converter-boosted to 55.2V.

Talking to myself here, did I violate a rule or something?

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?

OK got some answers elsewhere, but these posts have more detail, so will continue posting even if only FFR

Apparently, so long as there is **no** other connection between the input and output sides,

I can simply connect the negative voltage output line of the PSU, aka "energized conductor" to the negative "ground" input line of the load device, and connect the "current return path" (nominally local "ground" reference) output line of the PSU to the positive line of the device.

Does that all appear correct and proper to y'all?

_______
Next question: I have found instructions for isolating the individual modular rectifiers ( which can each operate standalone ) in the enclosure from their outer "chassis common".

But it seems this is not actually necessary?

By default each module shares a common reference via that "chassis ground".

I could enclose the case in insulation (liquid tape?), put huge safety-orange Shock Danger stickers on it?

That is, if there is any downside to my isolating the rectifiers from the outer chassis.

Is there?

Which way is safer?

Also FFR

$500 for a top notch telecom-class PSU, brand new NOS

Up to 7kva output ( ! ),

adjustable 44-58Vdc output, world power inputs, from 90-280Vac, 50/60Hz, very compact and quiet.

Each rectifier module can be used independently or if toed together on output, fed on the input side independently ( ! ),

e.g. 5x household US 10A circuits to get to 5kva, or multiple Honda inverter gensets.

The included control module on its own, often sells for higher than that $500

So, y'all think sounds like a good deal?

56.5V is my 100% Full cutoff for 16S LFP at high amps.

I will limit current manually, depending on size of LFP bank, certainly not exceeding .3C unless in a real hurry for some reason, very rarely, maybe up to 1C sometimes. And of course only if the upstream supply is big enough.

Plus of course fuses upstream appropriate for the source, and downstream sized for the target bank.

Safety First!