Getting Power from an outlet to a Police light bar?

Jim Brennan

Jim Brennan

VHS Member Old Skool
We are shooting a sequence tonight where we will be having a somewhat complex steadicam shot during a shoot out. We have a police light bar on top of one of the vehicles that hooks directly up to the battery. We don't want the car running because of potential audio problems, but we are afraid that the lights will run down the battery if it stays on.

We can turn the car on and off or disconnect the lights between shots. But if anyone has ideas for a converter to run the light bar (it has 2 little clips that go on to the battery like little jumper cables) to a grounded outlet, that would be great.

Thanks
 
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Impossible to say without knowing the current draw of the lightbar. This is normally on a tag affixed to the lightbar. Would guess a charged battery would give at least 30 minutes - most likely 2+ hours. Other thoughts -

Turn off lightbar and Start car (charge battery) between takes - cheapest.

Have a spare battery. (jumper cables from second car)

Borrow a automotive battery charger , place in parallel with the battery (warning - they often have a low level audible transformer hum). Will need to be large enough to handle current load of light bar. (20 amp should be safe - no guarantees).

Most AC to DC converters like those mentioned above are designed to run portable/auto 2-way radios as a base station. Power rating would likely be too low for a light bar.

Must post clips & b-roll !
 
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I don't know how actual cop cars are wired, but I rented a light bar from a prop house in town (Ellis - but they are no longer in business) and clipped it to the battery of the car I was using. Within 5 minutes, the wire almost melted. (Got the shot, though.) I know this isn't germane to your question, but a little side story.
 
(I had to spell check it. First guess was "germaine". Shows you how often I get to use it ANYWHERE!)
 
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