Design Issues and Solutions Running G40-bulb-style string lights on a battery

R45glasses

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Sep 12, 2014
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Washington, DC
Hi all,

A show I'm working on wants "makeup-mirrors," ringed by lightbulbs, on vanities that move around onstage during scenes. The pre-made led-on-a-battery-pack options I have presented have been vetoed, so I'm looking at powering a short string of globe lights off of a 12v battery. A cursory glance at how to do this often brings up the use of inverters, but there's not a lot of space to hide things on these vanities. My questions: How would you do it? Do I need an inverter between the battery and the string lights? If so, why? I haven't done a lot of battery powered practicals, and don't want to waste time (or money) in putting these together...

Many thanks!
 

sk8rsdad

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There are 12V and 24V incandescent light bulbs that can wired directly to the battery, preferably with a fuse in the circuit. Lots of selections for automotive bulbs but there's also a good chance they will be too bright for a stage practical.

It's a shame the LED string idea has been vetoed. We made a great looking sign for High School Musical using LED strings and ping pong balls.
 

danTt

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Aug 24, 2011
Location
NY
I'd also second thinking about 12volt lamps. It will be much cleaner than trying to source an inverter, disable any beeping, scale your batteries to handle it's inefficiencies.. etc

Now, I'm having trouble finding 12volt globes. You can get 25watt frosted or 50watt clear on 1000bulbs, and I suspect with a call in to them they can probably source a bit more of a range. Keep in mind that amperage at 12volts is going to be much more of a factor as you string things, and your wire gauge should scale to match.

A solution with leds inside of globes might be a better option depending on the specific needs of the production and specific skills of the production team, though a lot more DIYey
 

RonHebbard

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Waterdown, ON, CA
@R45glasses Been there, done that, sometime back in the 1960's. Back then 12 volt incandescent lamps were comparatively easy to source as they were being used in some farms, rural communities and mobile homes.
As everyone has wisely pointed out, watch the gauge and current ratings of your wiring and any switches used.
I found 12 volt lamps on 12 volt automotive batteries were FAR TOO BRIGHT. (Our director and designers preferred clear rather than frosted lamps although the frosted lamps were more flattering to cast members) I found running an even number of them in series connected pairs reduced their screaming WHITE color temperature to something more suitable for our production's purposes, reduced current consumption and increased battery life as well. Trickle charge your batteries between shows and check fluid levels if you're using non-sealed units. The weight of the car batteries located on a low shelf proved a bonus when it came to stabilizing the rolling makeup mirrors on their casters.
Toodleoo!
Ron Hebbard.
 
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Crisp image

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Jun 18, 2017
Location
Eastern Victoria Australia
@R45glasses
I found 12 volt lamps on 12 volt automotive batteries were FAR TOO BRIGHT.
What wattage globes were they. A 5w tail lamp should not be too bright I would have thought where as a 18w indicator lamp would have been.
Anyway I would use LED lights but as that is off the table Running 12v globes on a 6v battery or 24v globes on 12v would also allow a lower light output. If you are clever then you could use a DMX relay and a wireless system to turn them on and off.
Regards
Geoff
 

RonHebbard

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Waterdown, ON, CA
What wattage globes were they. A 5w tail lamp should not be too bright I would have thought where as a 18w indicator lamp would have been.
Anyway I would use LED lights but as that is off the table Running 12v globes on a 6v battery or 24v globes on 12v would also allow a lower light output. If you are clever then you could use a DMX relay and a wireless system to turn them on and off.
Regards
Geoff
@Crisp image IN HIS TITLE, the OP began by speaking of G40 (5") clear glass globes, 'Fat Alberts' as they were often termed, with their appreciably larger filament structures, NOT tiny automotive indicators.
Toodleoo!
Ron Hebbard.
 

Crisp image

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Location
Eastern Victoria Australia
@Crisp image IN HIS TITLE, the OP began by speaking of G40 (5") clear glass globes, 'Fat Alberts' as they were often termed, with their appreciably larger filament structures, NOT tiny automotive indicators.
Toodleoo!
Ron Hebbard.
Yes you are quite correct. (as most times) giving alternatives to try and solve a problem. :)
 

ship

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Mar 29, 2003
Location
Illinois
How I would start the R&D for project:
-What is the mind's Eye wattage of the makeup table lamp wattage/output? - This will get you to a comparable luminous output should you go low voltage or LED. Off source lighting as a start in finding perhaps there are some low voltage G-lamps.
-How long do the lamps need to be on per show in adding at least 1/4 to that. - This will get you towards the answer of amp hours = battery.
-How many lamps/makeup table section (assuming one battery per table)? - Above
-Budget & time? If you don't have budget or time - plugging or trailing the cord to a set piece has been for over a hundred years is the norm as a stage hand thing to do.
-Length of show run verses budget? If the show is only going to be up a few weeks, is R&D, than solution worth the time and expense?
-Dimming or control? Assuming dimming and control won't be needed - one will have to turn them off or on - sort of the same thing as plugging them in and a lot less effort than charging the batteries especially if you have a matinee performance before a night show.
-What size globes?

Assuming A G-16 thru G-30 size in globe light, and CRI isn't important, I recently "dotted a I" with a polypropylene ball cored out to mount a LED node. You can get side mount IP65 LED nodes, or nodes in general & specify the o.c. spacing between them, than drill a say McMaster #3748k35 ball to glue to the node. Other options would be to insert something like this: https://www.superbrightleds.com/mor...5-smd-led-tower-ba9s-retrofit-96-lumens/2543/ into the plastic gobe in a lot of choices for dialing in luminous output. Such lamps also don't need special unique power supplies and are often very compensating and forgiving for supplied voltage.

Believe I used epoxy gun 3M #DP605 epoxy to mount the ball, along with some drill press and Dremmel time in small project not taking up CNC time - though there is a lot of epoxy or even hot glue that could do this in applying globe to lamp, you still have to include time to fabricate this concept.

Hope it helps.