Andy wrote:
On Oct 3, 5:35 am, "Bill" wrote:
THIS DOES'NT MAKE MUCH SENSE
IT IS DOABLE BUT WHY ?
In my case, basically for higher reliability of some electronic gizmos. Also
to have pretty much maintenance free electronic gizmos so far as battery
replacement goes.

I live in a rural area and the electricity goes out at least twice a
month...

And I've had problems with phone answering machines which need to have the
time reset each time the power goes out. Or other models the batteries wear
out quickly during a power outage. So my phone answering machine needs
constant attention!

Then I have about 7 battery operated clocks (due to power outages), 6
battery electronic thermometers for temperature monitoring because I have a
wood stove and want to keep an eye on the temperatures when I am in other
rooms of the house, then about 6 battery smoke detectors / CO detectors
everywhere (again for wood stove monitoring).

Basically I frequently need to replace a battery in something. It would be
nice to have just one central battery and not worry about it except once
every several years!

Many items in the home can run off of DC; some can't. The big problem
with DC systems is excessive current draw and the corresponding
voltage drop. In order to use existing house wiring (12 and 14 ga),
the DC voltage would have to be much higher than 48V. At 48 volts the
current draw for any AC device would be more than double. Watts =
volts times amps. If your toaster draws 1000W and your voltage supply
s 48VDC, then you need over 20 amps to run the toaster. Standard
outlets are rated for 15A. Then theres the problem of motors (fans,
heater blower, refrigerator compressor, jacuzzi pump, etc). An AC
motor can not work on DC. However, many motors in the home are what
are called "universal" motors. These motors work for AC and DC. Most
power tools and small kitchen appliances use universal motors. For
example, a coffee grinder will run on DC, although it needs about
40-50V to get started.

And yet there is another problem of electric generation, and that's
another can of worms altogether. 100 years ago this country struggled
over the AC/DC concept for the electrical grid. Edison was a
proponent of the DC system, and Westinghouse was a proponent of the AC
system. There's a great book called "The Empires of Light" which
describes the technological and political wars related to this
struggle.

Having said all this, if I lived in a rural area, far from services, I
would have a DC battery storage system in my house/garage.

AG

At last someone who gets it. There have been others critical of
a separate DC power system and they have good point about why
you should not reinvent the wheel. Inverter technology has come
a long way in recent years and what would you think of a central
high capacity inverter coming off your battery bank. Many of the
backup generator systems I've installed over the years have not
been designed to take care of the whole electrical load of a
home or business but to supply power to the essentials through
a transfer switch and sub-panel. The same thing can be done with
an inverter system. By the way, Tesla is more of a hero to me
than Edison. I think Edison just had a better publicity machine.

TDD