No Name wrote:
Given that much of your hardware is on wall warts I wonder if a simple
car battery and a trickle car battery charger with some LM317Ts or even
some cigar lighter socket to Laptop PSUs set to the various voltages
required might be a more cost effective and electrically simpler and
more reliable option as then you do not have the conversion losses and
all the extra circuitry due to:

I wouldn't use LM317s as they're linear regulators, so waste a lot of energy
as heat. There are cheap DC-DC converter modules on ebay for a few quid
that can make whatever voltage you want, for much better efficiency.

However, if a lot of the gear takes 12V input I suspect it can tolerate the
voltage swings of a car battery (since it'll have an internal SMPSU) so you
might be safe to just wire all your 12V loads across the battery, perhaps
with a low voltage disconnect module (ebay again) to prevent
overdischarge. You'd need a charger that could handle all those
steady-state loads as well as trickling the battery.

That might be more efficient than two additional voltage conversions in the
chain.

Theo