On Thu, 22 Feb 2018 15:06:32 -0500, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
.. .
On Wed, 21 Feb 2018 11:22:46 -0500, "Jim Wilkins"
wrote:


If I can't find an AC/DC powered compact refrigerator priced as
reasonably as the AC-only ones I may be able to make the fridge
thermostat turn the inverter on and off. The real issue is the
APC1400
UPS inverter's 1.5A idle current, which consumes more battery
capacity
than the fridge does.

Your fridge takes less than 20w?

It draws 80W but not continuously. The average is close to 20W
although it depends too strongly on room temperature and how much I
open the door to give one definitive answer. On the last 12 hour run
the fridge used 230 Watt-Hours overnight, after supper to before
breakfast, while room temp fell from 60F to 55F. The APC which was on
wall power used 695W-h, 465 for itself plus the 230 to the fridge. It
appears to draw the same ~40W idle power whether on 120V or 24V.

Yeah, those things are always warm, even if the computer is asleep or
off. (feels TrippLite Internet Office UPS) Hmm, this one isn't. My
APCs and CyberPowers were always 90F+.


There had been several short power dropouts and I ran the fridge from
the APC UPS overnight as a precaution, not a careful test.

My present simple answer is add more batteries and let the APC and
fridge operate the way they were designed to. That's looking like it
might be the safest and lowest cost solution too. The APC's default
float voltage setting for sealed batteries also works for flooded
deep
cycle ones. It's below the hydrogen generation level though they
recharge rather slowly.

It's time for all of us to upgrade to LIPO (or better), huh? LA is
just not worth the effort and hassle. But 14kW goes for $6200
installed. I hope that price drops dramatically when the Giga
Factory
opens and gets up to speed, or when new tech hits the markets. My
single kilowatt will likely not be enough to satiate it, though.

Flooded lead-acid easily beats everything else for initial cost per
KWH and if treated right competes well on lifespan. I don't see the
life from older Li laptop batteries that I can get from LAs.

Your (and probably my) definition of lifetime is likely considerably
looser than that of others, who would consider a battery producing
only 70% of new capacity to be a throw-away item.


Here is an example of a salvaged EV Lithium that's 4x the cost of a
12V 105A-h SLI31MDC
https://www.ebay.com/i/112562977502?chn=ps

A "new" battery from 2015 Chevy Volt? Yes, expensive.
https://is.gd/Pspy7V Trojan T105RE (made for solar/wind) are about
$200/ea (6v) but are 225Ah, same relative cost as that lithium.


The APC1400 can be turned on or off by serial port commands, except
that it refuses ("NO") to turn on without AC present. Startup on
battery is an abnormal condition that requires pressing and holding
the On button until the buzzer sounds. I could probably wire to the
switch and buzzer to do that with an Arduino controller if simpler,
less intrusive methods fail.

I'm guessing that you want to retain the computer control rather
than
just hotwirin' logic to the SOB?

Whatever works. I have a lot of experience designing industrial relay
and digital logic control hardware, and writing control software.

Ayup.


Despite all the proclaimed concern about CO2 and alternate/renewable
energy it doesn't seem like many people are DOING anything about
them.

Some are volunteering to pay more to the electric company for power
which is supposedly produced with alternative energy supplies. Wind,
solar, geothermal, biomass (which burns something/adds to warming. I
still don't get why the alarmists go with that.)


Yeah, I've noticed that, too. 12v products are few and far between
while being ghastly expensive. Ditto point-of-use inverters.
For now, going 100% solar is really expensive and far too many
places
either won't let you on the grid, won't let you put up solar, or
they
REQUIRE you to be on grid with your panels. It's a mess.


Alternate energy is great to impose on others, as long as you don't
have to put up with the inconvenience of it yourself.

Done right, it's almost invisible rather than inconvenient.

--
However beautiful the strategy, you should occasionally look at the results.
-- Sir Winston Churchill