12 Volt DC Battery as Power Source for Camping

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I'm a total newbie to amps, volts, wattage.

I'm going on a camping trip into the desert for 2 weeks, so I've
purchased a Gel Sealed Lead Acid battery rated for 35 AH.  This will
power a combination of DC and AC devices -- mostly fun 12 volt LED
lights, my girlfriend's curling iron and music.

 My plan is to attach a cigarette socket with alligator clips to the
battery.  From there I will be able to attach a variety of things
including a DC/AC inverter.  I understand that the inverter will draw
extra power from my battery, so I'll keep that to a minimum.

I want to connect my small IPOD boombox (LANSING IM7).  This is a
small device that can run on batteries OR I can connect it's power
supply/cable to a 120 volt power source.  The input on the device says
17 volts == 2.3 amps.  I'd rather not invert this device because I
we'll be listening to a lot of music.   I'd rather be able to take
advantage of the DC capabilities.  The connector on the device is
small and round -- typical for an AC/DC adapter.

Can I purchase converters that will allow me to safely connect this
device to the cigarette socket adapter connected to the 12 volt
battery?  Or is this just not safe?

Any help is appreciated.


Re: 12 Volt DC Battery as Power Source for Camping



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The battery will not last very long, especially with the curling iron.
LED lites, maybe a while but with the loads you mentioned you will be
lugging around a dead batter in short time.

Tom


Re: 12 Volt DC Battery as Power Source for Camping


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Ok, without considering the loads I mentioned.  (The curiling iron is
only 45 watts and will only be used for 15 minutes), does anyone have
any advice about the boombox and inverting the power on that?

 want to connect my small IPOD boombox (LANSING IM7).  This is a
small device that can run on batteries OR I can connect it's power
supply/cable to a 120 volt power source.  The input on the device
says
17 volts == 2.3 amps.  I'd rather not invert this device because I
we'll be listening to a lot of music.   I'd rather be able to take
advantage of the DC capabilities.  The connector on the device is
small and round -- typical for an AC/DC adapter.


Re: 12 Volt DC Battery as Power Source for Camping



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It sounds as if you don't REALLY want to go camping ...
Perhaps a camp ground featuring screened cabins and
AC power as a compromise.




Re: 12 Volt DC Battery as Power Source for Camping




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17 volts seems like a rather strange input voltage... does it
perhaps charge up an internal battery?  If so, what is the
battery voltage?  If it's 12V you might be able to remove
it and rig a jumper straight to the cigar lighter connector.
In fact, even if the 17V input goes straight to powering the
device, my guess would be that it further regulates this
down to lower voltages for most of the circuitry, and only
uses the full 17V to power the output amp.  In that case,
you may get satisfactory results by connecting the 17V
input straight to the car's 12V cigar lighter connector;
you'd just have a slight reduction in maximum volume
from the power amp, but otherwise everything else
would work normally.

Or, just forget all that and go out and enjoy nature!

Best regards,


Bob Masta
 
            D A Q A R T A
Data AcQuisition And Real-Time Analysis
           www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!

Re: 12 Volt DC Battery as Power Source for Camping



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Try it and see.  You are unlikely to damage it unless it is a DC
adapter and you accidentally reverse the polarity.  It may work fine
on 12 volts.

If the adapter is an AC type it may still work with DC in - since most
use a full wave bridge to convert the AC to DC and the FWB will steer
the polarity so it gets to the amp in the right polarity.
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Re: 12 Volt DC Battery as Power Source for Camping



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Do you have any idea what a 12 volt 35AH battery weighs?  The
Universal Battery UB12350 is listed as 25 pounds.  Spec sheet here:
http://www.batterywholesale.com/battery-store/proddetail.html?prodID38%0
Do you really want to put that on your back for hours?  Maybe just
have the "gotta have a curling iron" person walk around with that
weight of books in a backpack for a couple of hours?  Then add  food,
water and other essentials...

I'd suggest a smaller battery and a decent solar charger panel
instead.  If you're walking more than stopping during the day, two
small batteries and two solar panels (one on each person, with the
panel turned to the sun) might work better.  If you'll be spending
more time in place than walking, a larger panel that is selfsupporting
can be set up to charge the battery during the day.

17 volts at 2.3 amps is easy, just get a universal laptop DC-DC
converter ($30-$70), select the correct voltage, and put on the
matching power plug.  These are usually 80%-90% efficient, which is
better than the DC-AC inverter.

If you must have electric curls, go to a camping/RV supply store and
get a 12 volt curling iron. Then you won't need the DC-AC inverter
with its extra weight and inefficiency (i.e., the battery will last
longer).  While you're at the store, ask for some help on packing -
you're taking WAY too much stuff.
My wife and I spent 3 weeks in the UK with one piece of carry-on
luggage and one small backpack each - we had room to pack our
souvenirs (Scottish wool sweaters aren't small) and the things we
brought back for other people.

John


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here:http://www.batterywholesale.com/battery-store/proddetail.html?prodID38%0
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There's more than one way to camp, people!  This is sort of a special
camping situation.

http://www.burningman.com

Thanks for the helpful replies.


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You mean that you and your girlfriend are going to get oiled up and set fire
to each other?

I have the solution to the curling tongs problem.  A hat.

No but seriously, have a good time.  As has been suggested, a solar panel
would charge that battery.  I think one of those gas fuelled Braun tongs
would be more practical really.  Or a hat.  :-)



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Yes, we're going to the Nevada desert to get oiled up and set fires in
the company of 45,000 other people doing similar things....but we need
music to make the experience really meaningful.  How can I make my
boombox run for 5 days for 4 hours per day using the battery that I
have?  Is this possible?


Re: 12 Volt DC Battery as Power Source for Camping


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No. At 2.3 amps, running 20 hours, that's 46 amp hours even
if you modify the boom box to run on 12 volts, and your battery
falls short at 35 amp hours. If we use the numbers you posted
(17 volts, 2.3 amps) it needs 39.1 watts. To provide power
to it through an inverter, figuring inverter efficiency at 85%,
it needs 46 watts, which translates to 3.833+ amps. Running that
for 20 hours requires 76.66+ amp-hours.

That said, it is highly doubtful that the boombox actually
_uses_ the 2.3 amps and 17 volts you mentioned. If it uses
significantly lower current and if you can modify it to run
directly off of 12 volts, then it _may_ be possible.

As others have mentioned, you need to add a charger and a source
of power to run the charger, and you need to lose the curling iron.

Ed

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Thank you, Ed, for answering my question.  If I promise to lose the
curling iron, will you tell me how to "modify it (the boombox) to run
directly off of 12 volts?"


Re: 12 Volt DC Battery as Power Source for Camping


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Sure - two methods:

The unit will play from 8 D cells, which equals 12 volts.
You can open the boombox up and solder a red wire to the
existing wire that goes to the positive battery terminal,
and solder a black wire to the existing wire that goes to
the negative battery terminal. You will need to find a way
to route the wires out of the boombox - through the battery
compartment is your best bet. The D cells must not be in the
box when you use this method.

The risk of this method is that you could screw something
up, and the downside is that you *must* remove the wires
before playing the boom box from the AC adapter or from
8 D cells.

There is another way, that is safer, but requires more work.
What you can do is make phoney D cells from wooden dowels.
2 of the phoney cells need to have a contact at one end that
mates with the contact in the boombox battery compartment.

Use measurements from a D cell to get the proper size.  The
purpose of six of the dummy cells is just to take up space in
the battery compartment so that the two dummy cells that have
a contact will be pressed against the mating contact in the
battery compartment.

Solder a red wire to the positive contact on one phoney D cell,
and a black wire to the negative contact on the other phoney
cell. Use stranded 18 gauge wire.  You will need to find a way
to route the wires out of the boombox. Best would be if you can
leave the cover to the battery compartment off and devise a way
to hold the dummy batteries in place - maybe with a cloth "sling"
that fastens with velcro straps that go all the way around the
boombox.

Whichever way you choose, it is *absolutely imperative* that you
get the polarity right. Get it wrong and you'll kiss your boombox goodbye.

With either method, the new red wire will get connected to the +
terminal on your 35 amp-hour battery, and the new black wire will
get connected to the negative terminal.  Use an inline fuse holder
like Radio Shack Catalog #: 270-1281 with a 3 amp fuse (Radio Shack
Catalog #: 270-1009) in the red wire near the battery, and an
on/off switch.

Ed

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I see, well when you put it like that I feel quite enthusiastic about a
solution.

Electricity unfortunately just isn't a reliable means of energy here.  If
you're looking for a beat then how about a drum?  No seriously.  A harmonica
perhaps.

The beauty of asking these questions here is that not everyone automatically
gets up and runs about screaming electricity-electricity, it must rule.

What would they have done 100 years ago?



Re: 12 Volt DC Battery as Power Source for Camping


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Then take the battery back to the store and get your money back, and go
buy a small Honda (or so) generator, and don't worry about what you plug
into it, as long as you don't go over its rating. You might even have
enough leftover watts to share with your neighbors. ;-)

Heck, you could even run a little fridge to keep the beers cold! ;-)
(be sure to bring generator fuel. ;-) )

Good Luck!
Rich



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you could try it on 12V, it might still work, and if not is unlikely
to be damaged by 12V.  otherwise get some cheap pc speakers that will
accept a 12V DC supply.

Bye.
   Jasen

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You're going camping!!  In the desert!!  With curling tongs!!  :-))))))

If I were you I'd put a stop this malarky straight away, and that's coming
from a techie female.  She can't take her toys else she'll have to stay at
home.

Anyway, the tongs.  Let's assume they draw 250w at 12volts.   250/12 = 20.8
amp/h.  If they draw 500w then that's 41.6 amp/h.

If she needs tongs then get her one of the little Braun gas ones, personally
I don't like them though, the heat is too dry.

Actually..  If you're in the desert then there'll be plenty of sun.  How
about one of those suitcase solar panels to charge the battery?



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Uh, don't you mean 20.8 AMPS?  Would last about 1.7 hours on a 35 A-hr
battery, or in reality less then that once the inverter losses are
factored in. (Not sure where you got these funny "amps per hour"
units.)

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Re: 12 Volt DC Battery as Power Source for Camping


Beth is leading you guys on...... curling irons in the desert off a 12 volt
battery.  You all ought to be ashamed of yourselves falling for this.  Hey
Beth... what are you doing the first two weeks of September?


Re: 12 Volt DC Battery as Power Source for Camping



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I have to agree with the other responders, you aren't about camping.
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