Re: Battery power television
- From: r2000swler@xxxxxxxxxxx
- Date: 29 Sep 2005 05:20:43 -0700
Clint
snip
Also for efficiency I would assume that it would make sense to charge
the cell phones using the chargers that are intended to be plugged
into the car battery via the cigarette ligher socket as they are doing
DC to DC. Same for the frs radios and the cb.
snip
Also for the computer (a Mac powerbook of my wife's) would it make
sense to get the accessory that allows it to plug into cigarette
lighter, bypassing the power converter? Would it be significantly
more efficient? Do you lose a lot of heat in the DC to AC to DC
conversion when you use a power converter?
\Clint
++++++++++++++++++++++++++++++++++++++++++++++++++++++
Yes
Very few inverters are more then ~60% efficent and then only at some
singl "magic" load. Dircect operation of electrical devices at 12V is
a very good way to not wate power.
One of the leasons I learned on April 3, 1974, the day and night the
eastern US was stomped by a series of tornados, was that important
electrical and electronic equipment needed to perate from +12V.
I was a college student living with my parents. I had a nice radio
setup,
but it requried 120V 60Hz AC. I had never thought the ligths could go
out for more then an hour or so. ~40Hr later when the lights came back
on I could once again listen to the world. I did not enjoy sitting in
the dark.
And I enjoyed the next day even less. Within 2 months I had my first
ham license, I hadn't seen aneed before, and I had added a mil suprlus
SW that would operate form 24V, or 2 car battereis in series. Over the
next few years I replaced my equipment, and added new equiptment,
that operated on 12V. During the years we have had power outages of
up to 48 hours and becaue my important gear operates from 12V
I was able to listen and talk to the world. My current "main battle
PC",
joke, is a mains operated Dell optiplex PIII/866. I have just bought a
"new"
PIII/1.4GHz laptop and plan to retire the Optiplex.
Any heat produced by your inverter is wasted energy. In the winter, if
you
have anough 12V, such as solar or wind, generated 12V this might not be
that big a deal. But if you are operating from a battery then any waste
is
bad.
Be sure to fuse at least the positive connection to the battery. A
charged
automotive lead acid battery has enough energy to burn #8 wire. This
will
be exciting and all too likely start a fire. BTDT and I still have the
scars!
I prefer gell cells, lead acid bateries that have the electrolyte in a
gell
so the risk of leaks is minized, but not completely removed. Good gell
cells can often be obtained form local alarm companies. The back up
batteries for high value assetss m,ust be chanege at 12~18 month
intervals, and these batteries still have years of life. You can't
charge
gell cells witht he cheapy automotive battery cahrges,t he will swell
and
burst, BTDT too.
Fro devices that operate on less tehn 12V there are "step" down
converters
that will give you 9/7.5/6/4.5/3/1.5V available and they are not at all
difficult
to build. Since ne of my main reasons for having stand by power is to
listenl,
and sometimes talk, via radio, I need as much RF quite as I canget. The
cheapist step down regulators are linaer, very RF quite but somewhat
wastfull. Fro instance if you have a 6V 6W device., 6V @ 1A =6W, the
downn
converter will waste an addtional 6W,(12V at 1 amp = 12W), since most
of my
less then 12V loads are either very light, my DX398 SW is 6V at ~100mA
with
the audio blasting wide open, ot intermitant like battery chargers, I
needed
RF quite over the slight gains in efficency. I haven't looked so I
don't know if
switdch mode 12V>9~1.5V down converters are even common. They do exist
because I have a few, but they completly jam radio recption.
Since comms are an important part of my life, and becuase my wife and I
like
to go on deep woods picnics where we take our 6V SW's I have several
smaller
6V gell cells that will each run a DX398, a set of LED light "wands",
and a
cassette recorder(intermitantly) for over 12Hrs. And advantage is that
in a real emergency I could connect these 6V gell cells and have 12V
to run the main equipment.
As to DSL versus dialup, I would have a dial up for backup but when we
loose
our lights, the phone is also almost always out. ICE storms take out
the poles
that support EVERYTHING!
As too keeping a car battery chargebreak it down in to steps.
1)Get a car battery and a small smart keep alive charger.
Most outages are going to be for a few minutes ot a few hours.
If the lihgts are out for mor then a 5 hours around here it means
things are real bad and it might be days before it is back on.
2)Buy a PV charger.
Or 1) call the local alarm companies and explain what you are doing.
I and several friends have had no trouble getting good, used batteries
I have a 20Amp/hour, a rating of how much capactiy a battery has,
running in hot standyby, ie when the mains fail my primary comm gear
kepep on working as though nothing happened. I have 3 more 20A/Hr
gell cells on constant standby but they will have to be connected to
the 12V "power grid" to come online. IT sounds a lot fancier then it
is.
Terry
.
- References:
- Battery power television
- From: brotherjohn
- Battery power television
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