A lamp needs
current to warm it's
filament. It does not care if it's
alternating current or
direct current. As long as you have
voltage sufficient to run the lamp, it's not going to care if it's AC or DC. There are some
filament notching issues on the subject of DC
current and your
halogen effect might not work sufficiently to extend the life of the lamp (buy extra because the lamps are more likely to blow given their high output and temperature in this condition). Otherwise, running a light off a battery should be just fine. If you can dim it, I would recommend starting it on a low
dimmer setting if not starting it before the show and leaving it powered up and on a low
dimmer setting
thru the show so as to ensure both the
filament is warm and if it's going to blow it's more likely that would be during start up. Sort of a soft start to it.
Osram makes a
HPL lamp that is 550w/64v, it's part number 54813. Otherwise the rest of the
dimmer duplexing lamps operate at 77v. Voltages available are 64, 77, 100, 115, 120, 230, 240 on
HPL lamps currently. As long as you can get into the range of the desired
voltage such as five batteries at 60v, than you should have sufficient light output with some
color correction. Since the wattage is over what you desired you would have to compensate for that in amp hours, but it would be a brighter beam of light which would compensate for the
gel thus your lamps can either be dimmed or as intense given the
color media in front of it. /Unfortunately at this time there is no
dimmer duplexing lower
voltage lamps available for the
Altman line of
fixture so the best you could do would be a 115v lamp on a 120v
circuit. There is also yet to be introduced a 375w lamp in the
dimmer duplexing range of
voltage.
Use of these lower
voltage lamps especially the 64v one would allow less
voltage on a battery thus a cost savings in both materials and amp hours. The lower
voltage lamps under battery might also not have as much a problem with the DC
current where
filament notching is in
effect also. (Basically the
current from one direction wears away at the
filament from the direction faster under DC
current than
AC current.)
Yes, by the end of the run, if you did not re-charge the batteries they would grow progressively
dimmer. That
voltage from a battery starts from the moment you
plug it in and every hour used it gets
dimmer. It's like a flash light, you don't notice it's getting
dimmer but it is every minute it's on it does. I would recommend buying batteries that are sufficient for the expected usage plus about half to double than re-charging them every night. This would assure your
intensity is constant every night and the same. It would also be cheaper to do.
Otherwise I believe if the last conversation on the subject was here, there were other options for
power transfer on a moving surface given
line voltage on a rotating
platform, if not just enough cable to twist as needed or manually
fed and twisted as it rotates. This might be a good idea to look back at since teaming together a bunch of batteries to boost their
voltage could be considered very dangerous to be around, not to mention that you than need to hide the batteries.
Be very careful about
safety on such a thing because a screw
driver thrown across a car battery will arc and weld if not start a fire. Such things are very dangerous and if possible especially even at 60v, much less 120v attempt if at all possible to figure something else out. In addition to all of that, be sure to compensate for the extra
fixture and battery weight on the turn table.
The lower the
voltage you go with the more safe the feature and more cost effective it will be. If you go battery, I would give serious effort to the lower
voltage lamps, also given the lower
voltage that dimming with battery
power will be much easier to compensate for.
When it's done, be sure and write up a paper for us on what you did and how it worked out. Such things are of interest to note and log for others in the future. Detailed information if not even pictures are very helpful. Just remember if not safe for others to use don't do it much less post it. Be careful. I get paid to do such things after years in the industry and an open budget for parts. If in doubt on doing it safely or on the cheap, don't. Otherwise hire a professional to do this for you. There is no excuse for ego over common sense and liability when it comes to doing things you have not done before. It very much might be more cost effective to have someone
build such a thing for you and let it be on their liability insurance than your's.
Primary source for such a thing I would recommend for you is Movable
Power as a company. The owner/manager knows what the heck he is doing and while expensive you would get what you pay for and he might just rent such a thing for you instead of you needing to
purchase the materials that are of limited value afterwards. Otherwise there must be at least 10 lighting companies in the Chicago area with sufficient skills to construct such a thing for you. Don't know if we have time but I would probably be on the list. If your
call list is in lighting companies includes where I work and my boss thinks it worth my effort I might end up constructing such a thing. Otherwise at least, Carl at Design Lab can probably construct such a thing if he still works there.
DMX tools if he wanted the liability could probably also construct such a thing. Let's leave it as chance as to figuring out where I am because doing so is not something I would really look forward to much less have time for. Plus I don't do business on
line.
A final option is to contact The Mayor's Office of Special events if your school is part of Chicago. Actually you will want the scene shop as contact Ralph, Jim or Jay. John Trick would be the person to talk to at the front office if you want results otherwise. A few years ago, I took apart a spinning snow man float and what ran them and the X-Mass lights was a huge one ton 120v
power transfer plate possibly even having the
spinner motors on them you would need for the
platform. (Been a few years thus I don't remember if the motors were saved but it's likely.) The things were probably rated for at least 30 amps in load and there was at least two in good condition plus one for spare parts otherwise needing work.
Curse myself for leaving them when I left there because nobody else would know what to do with them and they were
swag for the most part in being heavy and useless. Thus it might be possible that if you are in the Chicago school
system you can get such
power transfer plates for free, otherwise if not rent them. Ravenswood Special Events AKA, Ralph or Brian would be the contacts on rental or otherwise managing the scene shop. (Good summer work by the way, but about a month too late to apply.) In this way, you would get some huge center of your
platform pivot points with 120v
power transfer, and possibly more than one
circuit. Sufficient to both hold some extremely heavy spinning 8' tall spinning steel framed Snow Men and light them up. I saved the parts and remember at least two such units plus one needing work, otherwise in perfect condition. I kind of doubt such things will have been thrown out. Just a thought as to the best option I would look into were I doing this. At this
point, all the weight is centered and all you need to do is add floor outlets for
power. Plus you could control them from the light board.
[How many amps on a 750w lamp operated at 115v even if you use a 120v rating usually given a normal 118v power source? Might want to re-check the math. A 600w load at 120v is 5 amps should be a good thing to remember. Thus any 575w lamp is going to be 5 Amps with a safety factor. The less the voltage the more the amperage thus that safety factor.]