Balmar makes several regulators, I guess you are considering the ARS-5  or the MC-612    The also make some plain regulators, that don't have the advanced charge controller features.  Just being picky to make sure you get the right thing.

And I assume the specialty alternator shop understands you will be holding full load for hours while charging, and not the 6 minutes typical in a car or truck.  And the pulley size is the right ratio for your engine RPM & flywheel size.  Sounds good to me.  Keep us posted.

Mike
  (may look into this as an alternative to AC generator for 48V battery bank)

Carl, how many kw hrs per year do you get from a "1 kw" rated panel?

I'm not Carl, but with 5KW of panels, in a west orientation, in Los Angeles, I got 8MW output last year.
5/8 =  625KW per 1KW of panels/year

Your mileage may vary.

...lots of big radial engines...

Pictures start on page 5:

http://www.oldengine.org/members/diesel/Nov07USA/PimaMenu5.htm

Too cool, thanks. !

KIM-1 with hex display, built into a 3 ring binder.  Might have been the first notebook.

Roman Concrete would be my choice.  Barbarians trashed that knowledge.

A very dry mix, and pounded / packed into place, not the wet sloppy pumpable & pourable mixes used today.

I guess in fresh concrete, the PH is suitable for keeping steel from rusting, however with age,  CO2 diffuses into the cement, and lowers the PH, and then steel begins to rust, and the oxide flakes expand, cracking the cement.
 Polypropylene fibers, while not as strong initially as steel is, are fairly impervious.  Armaid fibers (and I suppose Kevlar too) are stronger, but at higher cost.   Even stainless steel fibers, seem like a better choice, but I'll tell ya, I don't want to mess with any cement with metal fibers in it - polypropylene looks like a couple of cats fell in the mixer, and all this "fur" is in the concrete, trying to work with that makes me itch.    Homemade - I guess you could take some SS cable, and chop it up into inch long lengths, pound it a bit with a hammer, and break the lay of the cable apart and add the "fibers".  The poly fibers were mixed in at the "factory" and were commercially made as additive.  The cement mix can also change the strength, between a 6 or 7 sack mix.
 So sandblast your rusty steel frame clean, zinc plate it or epoxy paint, and fill with cement.  (but cement  won't stick to a glossy painted flat plate, thats why rebar has the bumps and ridges in it , so it gets trapped in the mix.  Maybe tack weld rebar along the long flat members, give the concrete something to stick to.

  Instead of fiberglass strands, I will mix 1" carbon steel strands @ a ratio of 5-7% per volume as
recomended by the manufacturer, to give re-enforcement in virtually all angles.

How long will carbon steel last in concrete ?  I've seen rebar rust and expand, and completely destroy concrete.  I'd be concerned the steel (thin) will not last.   I've used chopped polypropylene fiber in concrete, and it's held together fine.

There are basically 2 types of batteries,  Flooded lead acid ( marine/deep cycle/forklift ) style, and the AGM "gel" cell type.

neither likes being left less than fully charged for any length of time, the deeper the discharge, or the longer at less than full charge, begins the irreversible "Sulphation Process" where crystals form on the lead plates, diminishing the capacity of the cell.  At some point, the cell generally fails from no useable capacity.

Flooded batteries can take a lot of overcharge abuse, as long as you water them.

AGM cells need very precise charge control, or else you boil off irreplaceable water.

  AGM has a bit of an edge in re-charge efficiency, near 90%   Flooded are only about 80% recharge efficient.

Each brand has it's own suggested recharge voltage, which varies with the temperature of the cell, so using a charger with remote thermal sensing is important