last minute electrical questions!

[Davoid]

Forgive me if I've missed this info elsewhere on this board; I'm faced with a quick decision and am overwhelmed by the info I've slogged through here and on the web.

I need to power a 117v plug-in strobe light in portable fashion. It seems the inverters I can get before leaving are all of the cigarette-lighter variety. Can I make a basic hardwiring adjustment so that I can rig one of these inverters directly to a 12-v battery?

Also, this application is only needed for 2-3 hours at most. I can get a regular 12-v battery, and not need to go deep-cycle, yes? Or...?

[b00m3rang]

Electronic stores such as Radio Shack should have a female lighter receptacle with two wires attached. Just put ring terminals on them and screw them to the battery terminals.

Or, you could just cut the wire that connects to the cigarette lighter plug and wire that to the batter. Just make sure you get the polarity right.

[Davoid]

The Radio Shack clerk couldn't really help me with these questions, and of course I saw no appropriate female adapter. So if I'm just gonna snip the wire, is it obvious which is pos. and which is neg? Wish I had one in front of me, so I could determine if that's a dumb-ass q. or not...

(and thanks for the speedy reply!)

[b00m3rang]

Just disassemble the original plug, and follow the wire to figure out where it goes. The center conductor at the tip is positive, the one on the sleeve is negative. Usually there's a stripe or ridge on the negative, but it's good to doublecheck.

[b00m3rang]

I just remembered, the shack should definitely carry a Y adapter (for hooking up two devices to one receptacle). You could get one of those and just cut off one of the two female connectors and use that, if you're interested in salvaging the original connector.

[Gravity Mike]

Also, this application is only needed for 2-3 hours at most. I can get a regular 12-v battery, and not need to go deep-cycle, yes? Or...?

You don't *need* to go deep cycle, but if you expect the battery to last you should. I use an old car battery that still has life in it as a deep cycle, but I'm technically abusing it. Our camp just got 2 deep cycles for powering our dome lights and 'beacon' at night with the genny off.

If you're buying a battery, just get the deep cycle. If you have an old car battery lying around - go ahead and use it if you don't plan on putting it back into a car.

Also, the integrated load is something to consider if you're buying a battery (or to see if the old one lying around will do the job). Consider what the load and time of usage will be. If your strobe is 240W (let's say), that's 2 Amps at 120V, or 20A at 12V (and this does not consider that the inverter itself eats power, 10-15% anyhow). If you plan on running the lights for 4 hours/night, that 80 Amp-hours. The deep cycles our camp just bought are 85 Amp/hour batteries. For this load/usage, I would recommend 2 batteries connected as a bank. Even deep cycle batteries should not be fully discharged (again, if you expect life out of them), so the system needs to be oversized. BTW, you won't find an 'amp-hour' rating for car batteries because they are not intended for that use. I would guess 50-70 is typical, though.

How we messed up our old batteries - they should be stored the other 51 weeks of the year charged. You can get these micro-chargers that maintain batteries in storage. We only got one year out of our old deep cycles because we did not do this.

Gravity

[dinosaurwilly]

Best Buy has power inverters that come with clips so you can attach it to your car battery. This is the ideal situation if you are planning on drawing high current. I suspect a strobe light might blow the fuse on the cigarette lighter.

http://www.bestbuy.com/site/olspage.jsp ... 2287374780

"The Captain"

[Davoid]

Thanks for the suggestions. The problem with a car battery is that my application is part of a costume, so I need something I can carry around with me. It's also not a costume I plan on using more than one night, in transit about the playa only, though I may use it again next year or elsewhere.

I was looking at some of the smaller deep cycle batteries at Fry's, where I also happened to get one of the smaller inverters (with car adapter extrusion) and a female-car-plug-to-battery-clips adapter. I was eyeing one of the inverters that had the battery attachment built in, but I'm on a tighter budget this close to rent being due, and they're pricier. Anyway, tomorrow I buy the battery, either at Radio Shack or Fry's, so we'll see if it blows the fuse and y'all will see my costume in 2006 instead. Unless my GF feels like covering me for a few more ducats.

[phil]

The problem with a car battery is that my application is part of a costume, so I need something I can carry around with me. It's also not a costume I plan on using more than one night, in transit about the playa only, though I may use it again next year or elsewhere.

How many amphours do you need for your couple of hours? Carrying around a car battery doesn't sound like a lot of fun unless you have a trailer or travois or something. There are lots of Sealed Lead Acid Batteries around that won't start a car but that have 2 to 7 Ahs of 12VDC in them. No worry about spilling the acid in a SLAB.

I have some blinking LEDs that are 120VAC, but that feeds into a brick that converts to 5VDC, so I bought some 4.8V batteries, cut the power cord between the lights and the brick, and spliced the batteries in to feed 4.8V to the lights. They work fine, but not quite as long as when plugged into the wall. :-) Is this an option for you?

I carry around a 12V SLAB to power my ELP display at night. I get a couple of nights use out of each 2Ah battery. I wear a WWII-style webbed pistol belt with the battery in the ammo pouch. A perfect fit.

[Davoid]

That's what I was looking at, Phil, although I think the one I was gonna get was 4Ahs instead of 2, and still very doable in terms of weight. Still didn't buy (or test, obviously), 'cause I couldn't get an answer out of any of the Fry's or Radio Shack staff as to the best way to charge initially. I guess I shouldn't expect them be electricians; I'm sure they're quite knowledgeable about cell phones and the rest of their more common wares.

Anyway, I bought a little ciggy-lighter-to-bare-wire adapter with the thought of charging from the car batt. during the 10-hour drive to BRC. Now I'm gonna re-slog through all the deep cycle posts to see what my options are there, and how to keep it alive once I get back. It's either that or spend a similar amount on a regular 12-v alkaline battery.

Thanks again for the replies! Slowly, slowly, I emerge from my ignorance...

[HughMungus]

What are you powering? Maybe I missed it. If it's just some lights, I have a solution.

[phil]

Anyway, I bought a little ciggy-lighter-to-bare-wire adapter with the thought of charging from the car batt. during the 10-hour drive to BRC. Now I'm gonna re-slog through all the deep cycle posts to see what my options are there, and how to keep it alive once I get back.

Radio Shack is your friend. You can buy cigar plug rechargers and wall wart rechargers to use at home. If the battery has small tabs for charging, you can buy little spades that crimp onto your wire and fit snugly over the tabs -- spades on both the chargers and the lights.

[Davoid]

Dallas- yes, I'm powering just one strobe light: 117v, 60HZ, max .2amps. Not the serious kind, just a very small one.

[HughMungus]

Dallas- yes, I'm powering just one strobe light: 117v, 60HZ, max .2amps. Not the serious kind, just a very small one.

Oh, OK. If you said christmas lights I was going to suggest the kind that are already battery operated. No idea how to power a strobe, sorry.