12v and 120v power options

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skippy3k
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12v and 120v power options

Post by skippy3k » Sat Mar 07, 2015 8:46 am

I hesitate to post another question about power choices for lights, but I wanted to take all of the posts I have bookmarked and studied, condense it down, then hopefully you can tell me if I have the basic idea. That would allow me (or anyone else) to later see what their options are. My application here is for our mutant vehicle, but I think the principals are the same for any situation requiring power. Obviously I can't cover all of the pros and cons, but please let me know if I'm missing something big.

What I have to work with
I have a 2000w generator and set of Trojan batteries which together rate at 225AH. Light choices will be either 12v LED's or a combination of 120v LED's and fluorescent. Assumptions are that lights will only be run at night and that the vehicle alternator is being dedicated to basic vehicle functions.

Option 1 -- Generator powers 120v lights directly. (Gen -> 120v power strip -> 120V lights.)

Pros - Efficient use of electricity. Choice of 120v LEDs and flourescent, which are inexpensive and use standard plugs.
Cons - Generator fails, no more lights.


Option 2 -- Generator (re)charges batteries as batteries power 12v lights. (Gen -> 12v batteries -> 12v lights.)

Pros - Generator fails, lights still work for awhile.
Cons - No fluorescent, no standard plugs. (12v LEDs not as efficient...?)


Option 3 -- Generator (re)charges batteries, batteries power inverter, inverter powers 120v light. (Gen -> 12v batteries -> 120v inverter -> 120v lights.)

Pros - Choice of 120v LEDs and florescent
Cons - Inefficient use of electricity, higher cost with purchase of additional inverter

Am I pretty close?
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Roundabout
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Re: 12v and 120v power options

Post by Roundabout » Sat Mar 07, 2015 10:31 am

12V LEDs are highly efficient.
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Re: 12v and 120v power options

Post by digital » Sat Mar 07, 2015 10:33 am

Roundabout wrote:12V LEDs are highly efficient.
This.

And inverters are highly inefficient.

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Re: 12v and 120v power options

Post by Captain Goddammit » Sat Mar 07, 2015 1:36 pm

Been there, done pretty much all that...
Technically, if you are using a 12-volt power source then 12-volt LEDs should be more efficient because you avoid a bit of loss through the inverter.
But, in the real building-a-mutant-on-a-budget world, I think that's not the most important consideration.
I've found that 120VAC LED and fluorescent lighting is a lot cheaper to obtain, and if you're running an alternator or generator, you can afford the slight loss through the inverter. It's no big deal.

The problem with the idea of running on the batteries and keeping them charged with the generator is battery charger capacity. That system will be VERY inefficient and you would need a really large battery charger. The electrical draw on my modest sized, reasonably well lit M/V with all LED and fluorescent 120 volt lights running through an inverter is around 50 amps (at 12 volts) from my batteries. More if I turn on everything I can. You'd need a battery charger that can continuously put out that kind of amperage. That's a damn big charger.

If the generator is your choice, I'd run directly from it, and carry spare maintenance parts to be sure you can keep it running. If you have an inverter I'd say install it anyway. Whatever power you can get from your existing alternator will run at least some of your LEDs and get you by in the event of a generator failure. Some backup is better than none.
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Re: 12v and 120v power options

Post by maladroit » Sat Mar 07, 2015 3:56 pm

The system requirements change depending on how big it is, so it's hard to verify or recommend various solutions without that information. For example...if you have 5 strips of 12V LEDs, run them on your batteries and charge the batteries in camp every few days. But that might not be a viable solution depending on how many lighting fixture you have, how far apart they are, how many hours they need to run, etc.

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Re: 12v and 120v power options

Post by Captain Goddammit » Sat Mar 07, 2015 4:14 pm

Good point, but I think we can assume we're talking about enough lights to get a night time DMV license, and that's hard to do on less than a few hundred watts.
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Re: 12v and 120v power options

Post by skippy3k » Mon Mar 09, 2015 6:19 am

Thanks for the correction on 12v LED efficiency. I'm not sure where I picked that bit of misinformation up.

Captain - great point about the battery charger. That is what I was look for....those things I missed in my overall understanding.

Maladroit - I totally agree, knowing the system requirement would allow others to say "you need an X big inverter to power Y". But I was purposely omitting my power requirements so that I could take a step back and understand the options available to power lights. (Granted, I did omit solar as one of the options.)
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Re: 12v and 120v power options

Post by skippy3k » Mon Jun 29, 2015 9:35 am

So just to circle back on this because I know none of you have been able to sleep, wondering what I ended up doing. As is very common with most grand plans, especially involve BM prep, the solution you end up with is not even close to where you started out. But the journey along the way was very, very educational. In the end, I was able to upgrade to a 90 amp alternator and went almost all 12v LED's. I did add a couple of 120v fluorescent lights running off an inverter to each underside of the MV, mostly because I liked how they dispersed the light. However, the 120V inverter and the 12v LED's are independently switched, so I have the option to run one or the other or both.

With my new found knowledge of electricity, I am running the numbers and the total amp draw of everything running (including the music) is slightly less than half of the alternator output. Ah, but what able the fact I'm crawling at 5 mph? Will the alternator be able to ramp up enough to generate the electricity needed? Early tests are showing yes. By "tests" I mean the alt/gen idiot light that VW provides for Beetles is supposed to illuminate when the alternator is either not able to keep up with the draw from the batteries, or otherwise is in a failed state and is unable to charge properly. When idling in my garage, the light fires up and then goes out as expected. When I force the idle below 500 RPM, the light begins to glow again...which is what I expect when the alternator isn't spinning fast enough. (Proper VW idle is about 900 RPM). Funny how my hopes and dreams of getting a night license is being based on a single, tiny light bulb. I need to do a proper test and actually drive it 5 mph around the neighborhood to verify the charge is enough, but leaky brake cylinders are preventing that for now. Worst case scenario is I can replace the alternator pulley with a Porsche 356 pulley which is smaller and will increase alternator spin at lower RPM's.

But for now it looks good. The MV is a reality, has been pre-approved by the BMorg and assuming it doesn't blow up between now and then, will be on the playa this year.
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Re: 12v and 120v power options

Post by digital » Mon Jun 29, 2015 10:11 am

Nice work! Just finished a similar, albeit smaller, project myself. That is, LEDs on the underside of transportation. Fun project.

Look forward to seeing you out there. Don't forget a few pics. BTW, are you controlling the LEDs with anything?

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Re: 12v and 120v power options

Post by Captain Goddammit » Mon Jun 29, 2015 10:20 am

Whew, thanks for the update!!

As the owner of an MV that uses LED lighting and fluorescent lights on the bottom driven by alternators and an inverter myself, I'll add a few comments.
Do go ahead and put the smaller pulley on your alternator. It's cheap and easy. You'll want all the charge you can get.
You don't need to actually drive it around to see if the electric system will work. Just run it at idle.
Don't base everything on the idiot light, it isn't telling you what you really need to know. Hook up a voltmeter and see if your voltage is slowly dropping or holding steady. Run the thing quite a while and make sure.
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Re: 12v and 120v power options

Post by EspressoDude » Fri Jul 03, 2015 7:03 am

also, automobile generator and alternator output is rated at a fairly high rpm. An older Delco alternator is rated 32 amps at 2000rpm, but 63 amps at 5000rpm.
keep in mind that the generator or alternator field will take 4 - 5 amps.
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Re: 12v and 120v power options

Post by Captain Goddammit » Fri Jul 03, 2015 10:15 am

I really hope you're reading this! The things you've described are sending me red flags, and I don't want you to have trouble on the playa.
Driving around the neighborhood at 5 mph isn't a good test, because you likely won't put that much time into it. And the charging system doesn't care if you're crawling at 5mph or just idling in place.
Your alternator will make a whole lot less current at idle speed, and idle is where you'll be operating.
You really need to get a volt meter, idle the engine, turn on all your stuff, and watch the voltage. It should hold steady. Give it an hour or so,, if it slowly drops while idling with all your electrical stuff turned on, you aren't getting enough current and you'll end up with a dead battery.
I ended up using two alternators because one at idle speed wasn't enough. And they are "105 amp" units.

Forget the theoretical numbers that say you're all good, based on an assumption pulled out of thin air. I've seen many an art car run its battery dead on exactly the setup you're describing.
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Re: 12v and 120v power options

Post by skippy3k » Tue Jul 07, 2015 7:06 am

I am reading and absorbing all of this. And trust me, I haven't slapped the "Solved" label on any of my electrical concerns. The fact of the matter is no matter what I do, I won't be totally at ease with anything until it's day 3 on the playa and everything is still working well. That being said, right now, all I have to work with is theory and assumptions until I am able to test it more. But after being faced with one challenge after another after another in building this art car, I am taking a little solace and joy (otherwise I'll jump out the proverbial window) on the fact that there doesn't seem to be an IMMEDIATE and OBVIOUS lack of charging. Meaning, if I hooked up all the lights and ran the engine and the alternator CLEARLY showed it wasn't up to the task, I would be facing yet another disappointing blow in a long list of disappointing blows that is inherent in any mutant vehicle project. The fact that I didn't see that gave me hope. That's all....hope. And at this point, working on it mostly alone for 6 months, hope is the only thing keeping me going.

I will do the volt meter test, which I have done before but not for an hour. I will test, idle, drive, test, idle, drive and test again. I will worry and add up numbers and test again and worry some more. This will continue until it hits the playa. But at least, for now, the lights work. I am happy. Satisfied? No. But happy, yes.

Oh, and sorry for missing the LED question. No, I am not controlling the LED's with anything. They are just single color LED's split up by multiple toggle switches on a panel I made, allowing me to power on/off various sections as needed. (Driving lights and parking lights, if you will.) I will get some pictures posted soon, once I am not entirely embarrassed by how it looks. Since I'm building it in my garage, I can't have the posts and roof on so right now it looks like I spent 6 months building a platform on wheels.
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Re: 12v and 120v power options

Post by skippy3k » Wed Jul 08, 2015 6:16 am

Ah, so I re-read my previous "update post" and realize in my excitement I left out a very important bit of information. I am not running everything off of the alternator as it may have sounded. I neglected to mention that I have three batteries; a regular starting battery and two 6-volt Trojan T105's wired in series. Rated at 225AH, even if they give me 200AH (or hell, 180AH), I could run just the LED's all night without even starting the MV. But obviously the car will be running. Hopefully. :wink:
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Re: 12v and 120v power options

Post by Captain Goddammit » Wed Jul 08, 2015 7:19 am

You still gotta charge those batteries though.
I've been directing so much attention to your MV because I'm just like you, building by myself 700 miles from BRC, and my setup is strikingly similar, a starting battery, two deep cycle "house" batteries, alternator and inverter running LEDs and fluorescent tubes on the underside.
One other learned-from-years-of-doing-this-shit I'll mention: spare parts! Bring every possible spare everything you can. It sucks to do all that work, trailer the heavy goddamm thing all the way out there, and blow your one chance to play with it because of some part that fails. Spares of all sorts have saved me several times. Even if you only have a used stock alternator, bring it.
I've had flat tires out there and last time I even had the center of a wheel crack out. I've had a starter fail, alternator, various other stuff. Each time, everyone thought I was finished, but I set up lights and wrenched late into the night and was rolling the next morning, because I brought everything I could.
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Re: 12v and 120v power options

Post by skippy3k » Wed Jul 08, 2015 9:59 am

I'm all over the spare parts. It's a 1970 VW engine so fortunately they don't get much simpler than that. Extra points, condenser, distributor cap, belts, fuses, coil, plugs, etc. Fluids, even bringing my enclosed environmentally safe container to store oil in case I need to drain something. And enough tools to employ a fleet of mechanics. Some stored on the car, some at camp. Wiring. Welder. Nuts, bolts, screws, JB Weld (I love that stuff) for inevitable structural repairs. Spare tire. Fix-a-flat. Fire extinguisher. And, like you mentioned, I'm even bringing the original stock alternator. Mechanics is the one part I am comfortable and familiar with. So is overpacking. :D

As I work on this project, I gain more and more admiration and respect for those who do REAL BIG art installations and mutant vehicles.

And thanks Captain for watching this thread. As you probably know, it's nice to bounce idea off of people....and I think my wife is tired of hearing about which bearing I should use for the steering.
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Re: 12v and 120v power options

Post by skippy3k » Mon Aug 24, 2015 8:14 am

Idling for extended period of time with lights on!

:D :D

The smaller diameter Porsche alternator pulley really helped. Now I'm looking forward to spending 1 week enjoying 9 months of work. :roll:

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Re: 12v and 120v power options

Post by Capinator » Mon Sep 21, 2015 5:30 pm

I learned a couple of things this year that were useful, and related enough that I shouldn't start a new thread.

In camp, we had 120v everywhere, and 12v nowhere unless I ran a dedicated 12v line. In places where we only had a few LEDs, it would have saved me a lot of work to have a 12v wall wart instead of running a new 12v line. Yes, it is incredibly inefficient to run an inverter off a 12v battery, only to plug in a wall wart to convert the 120v back to 12v. But - compare that to me having double wires run everywhere (and increase the crap and tripping factor) and I'll take the wall wart.

Where we had a lot of LED 5050 strips, I did run dedicated 12v lines because they start to add up to a lot of current and the efficiency becomes important. We had 15x5m strips running in a tent, which was something north of 20amps at 12v.

Arduino+DMX shield+LED Strip DMX controller = lots of cool stuff that you can do pretty easily. I spent a LOT of time trying to figure out how to control a lot of strips independently - this seems to be the easiest way. The other option calls for a lot more soldering.

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Re: 12v and 120v power options

Post by spacetime » Tue Sep 22, 2015 8:08 pm

Capinator wrote: In camp, we had 120v everywhere, and 12v nowhere unless I ran a dedicated 12v line.
Thanks for the info.

What were the primary uses of the 120v by your camp mates?

Can you go into more detail as to how you used the 5050's around the camp, and some of the cool things you did with the combo you mentioned? (maybe photo or video?)

How did you approach general camp lighting?

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Re: 12v and 120v power options

Post by Capinator » Tue Sep 22, 2015 10:44 pm

those are great questions, and I wish I had better lighting pictures.

for 120v, pretty mundane stuff - fans, pumps for swamp coolers, pumps for greywater to the evapotron, battery chargers, air pumps for air mattresses, stuff like that. We had three structures - so when you have a fan in each one - 120 is already there. And 120 is very easy to distribute via well known extension cord technology ;-) 12v you are custom wiring everything.

For 5050s, I wish I had better pictures, maybe I'll set it up here at home if I get ambitious. I made a box that can control up to 16 strips individually. There are three rotary encoder knobs that control things like hue, saturation, brightness, and speed of a wipe. And LCD screens to tell you what's going on. So, you could set all 16 to one color and brightness for general illumination, or do a trippy wipe through the color wheel at various levels of saturation, speed, and brightness. It's pretty cool! I'm a mechanical engineer cum attorney, not a coder or an electrical engineer, so there was a lot of trial and error for me. Eventually I got it right. I almost got all the way to sound reactive lights. I have all the hardware and code pieces in place, but it became very low priority as we scrambled to the finish line. Next year I'll get that down.

If you are into arduino, this shield,

plus a controller like this (I used two of these, but there are better lower cost options)

i don't know if putting the links in is allowed or not. I'm sorry if not. If you search for DMX shields and 5050 strip DMX controllers you will find what you need.

The point is, if you get the hardware and code in place, it will let you control lots of 5050 strips and you can do some crazy stuff with 5050s, which are inexpensive. I'm an engineer, not an artist, so my lights were pretty linear but still cool. With more input from the artsier members of our camp, I'm sure the lights will be more interesting next year. Current becomes an issue, so you will need to power that many strips straight from a 12v truck battery. We had two group 31 marine batteries. Once you get the pieces in place - imagination is the last barrier!

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Re: 12v and 120v power options

Post by skippy3k » Wed Sep 23, 2015 6:55 am

This reminded me that I should maybe post the finished product, just to show I actually did it. :wink:

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Re: 12v and 120v power options

Post by Captain Goddammit » Wed Sep 23, 2015 6:30 pm

LOL, what the fuck is the switch labelled "EJECT"?! I need that one.
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Re: 12v and 120v power options

Post by skippy3k » Thu Sep 24, 2015 8:29 am

Captain Goddammit wrote:LOL, what the fuck is the switch labelled "EJECT"?! I need that one.
When I was asked on the playa about it, I answered seriously...it ejects. It was fun to see the person smile, and then when they noticed I wasn't smiling, their smile faded, then tried to come back, then faded entirely as the silence grew between us.

My kids asked me what it did during the build, and when they started to touch it, and I yelled "Don't do that!!!". One of those "dad moments" that you gotta do, even though it will incur an additional thousand dollars or so of therapy bills later for me as they get older.
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Re: 12v and 120v power options

Post by Captain Goddammit » Thu Sep 24, 2015 9:45 am

I like it. One of my old art cars had a fire cannon and the switch for it was labelled "NEVER USE"
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