Re: Power Supplies, Saving Money, and switching vs. Linear?

["RoughRider" <Post@xxxxxxxxxxxxxxxxx>]

I took your $56/month and divided it by $0.11/kwh (all inclusive sample cost
out of your pocket) = 509 kW/month divided by 24hrs divided by 31 days = 684
Watt continuous load.  This sounds very high.  You would have 2,330 BTU/hr
of heat assuming all this energy was used within your closet.  It would be
very warm/hot without proper ventilation.  This figure does not sound right
for what you are describing.

A linear power supply is most efficient when near fully loaded.  The
transformer core magnetization current is constant no matter what the load.
A switch mode supply is more forgiving when lightly loaded.

As others have stated, check the theory on the difference between VA and W.
You are *not* paying for V x A on the AC side.  You are paying for WATTS
only.  Or measure and calculate V x A on the DC side and multiply by 1.25
for the power supply efficiency to reflect an approximate cost on the AC
side.  A good switch mode supply should be 87 to 94% efficient while
consumer grade switchers will be slightly less (~77%).

Charging a small battery (10 AHr) isn't usually a big deal.  The float
current is sufficiently small (10 to 20 mA = .28W worst case).

Turning off unnecessary parasitic loads will have a more significant impact.

Good luck.