12 Volt DC Battery as Power Source for Camping

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.

Reply to
beth.stover
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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

Reply to
Tom Biasi

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.
Reply to
beth.stover

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.

Reply to
Lord Garth

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?

Reply to
Aly

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

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Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!

Reply to
Bob Masta

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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Reply to
default

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

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Reply to
default

You need all that + a curling iron while camping? Just pitch a tent in your back yard and run an extension cord. :)

Reply to
Meat Plow

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.)

Reply to
redbelly

Do you have any idea what a 12 volt 35AH battery weighs? The Universal Battery UB12350 is listed as 25 pounds. Spec sheet here:

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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

Reply to
John

here:

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There's more than one way to camp, people! This is sort of a special camping situation.

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Thanks for the helpful replies.

Reply to
beth.stover

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. :-)

Reply to
Aly

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?

Reply to
beth.stover

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

Reply to
ehsjr

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?"

Reply to
beth.stover

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

Reply to
Jasen Betts

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?

Reply to
Aly

forget it - sounds like you are about camping as much bin laden is about democracy.

just stop at a motel... I mean... curling tongs as essential camping kit.

Seriuosly, don fsck with the desert, you are a prime candidate to end up as a statisitic, bitten or stung or lost or died of thirst, or worse still - caught without l'oreal :o)

Reply to
feebo

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

Reply to
ehsjr

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