Battery powered headlights for prop car

[claw88]

Hi, 

I am involved in a production of The Wedding Singer this year, which involves a prop Delorean, from a front perspective. 

Keen to have some working headlights within the build of the car, but ideally something battery powered that can be operated by stage crew.

Interested in any ideas to achieve this, with a set of old headlights maybe, or any other ideas.

Thanks

Chris

[DrV]

Depending on how long they have to be on, you'll probably want to use LEDs rather than incandescent lamps. There are some nice LED indicator lamps which are surprisingly bright but use only 100mA or so, so you can run them all week off a 12v 7Ah battery. If they're pointing straight at the audience you won't want them to be the same brightness as real headlights!

[KevinE]

I did somethihg similar a few years ago where a client wanted 'cordless' par64 cans. (for effect, not for lighting a subject!). 

I fitted some 12V led lamps in place of the original holders, added a boost converter pcb (readily available from the usual sources) and ran them off a USB powerbank. This way they could be recharged quickly and safely with a system that the layman could understand.

Edited September 7, 2023 by KevinE

[Robin D]

Four of these or similar fitted with suitable BC LED would look fairly convincing from the front. They would also look the part even when off. 

[J Pearce]

LED is nice, but not really necessary if it becomes complicated. If the truck is a full size car front then it'll easily accommodate a golf cart or leisure battery (and probably benefit from the weight). Add some suitably shaped car headlights from a scrap yard. If you want the lamps to run dimmer wire them in series. Add a crew operated switch.

Halogen car headlights are only 55W. A pair is 110W, which is just shy of 10A. You wouldn't need a particularly large battery to run them for an hour.

[sunray]

9 hours ago, J Pearce said:

LED is nice, but not really necessary if it becomes complicated. If the truck is a full size car front then it'll easily accommodate a golf cart or leisure battery (and probably benefit from the weight). Add some suitably shaped car headlights from a scrap yard. If you want the lamps to run dimmer wire them in series. Add a crew operated switch.

Halogen car headlights are only 55W. A pair is 110W, which is just shy of 10A. You wouldn't need a particularly large battery to run them for an hour.

Depends on how many shows and how often, in theory a 12AH would run that but BUT fully discharging that fast is not good, lead acid batteries are usuallysized at 20 hour rate so Personally I'd look at 100AH as a minimum. (10 hour rate). I learnt the hard way with 600W of 50V lights on a carnival float and 4x 40AH standard car batteries didn't run for 2 hours or last a whole season.

However without knowing if 'full power' is required for the effect, I'd be thinking to replace the 55W bulbs with something smaller, 21W brake light springs to mind and suddenly 1/3 of the current and 40AH battery, 6/21W springs to mind if the effect of dipping the lights is required.

But quite honestly some 3-7W 12V LED G4's seems better to me and a 12AH will run a weeks shows.

Edited September 8, 2023 by sunray

[J Pearce]

18 minutes ago, sunray said:

Personally I'd look at 100AH as a minimum.

All depends how long it's lit for per-show. For most cases a 30Ah golf cart battery would be fine. But a 90Ah leisure battery would have some spare and maybe have a happier life. 

I've actually done this. For real. In an actual show. Several times. It was all fine.

[cedd]

How much to hire a case of battery powered LED uplighters as used in marquees for weddings etc? Wireless DMX, built in batteries, and if they came as a package of 6 as they usually do, you could use the others elsewhere for the set. 

[the kid]

4 hours ago, cedd said:

How much to hire a case of battery powered LED uplighters as used in marquees for weddings etc? Wireless DMX, built in batteries, and if they came as a package of 6 as they usually do, you could use the others elsewhere for the set. 

was just thinking that. 

Depending how precious you are about looks something like AX3 would be perfect , print a small holder and slot them in job done. 

[claw88]

Thanks all for your responses, all really helpful. The lights only need to be on for one scene of the show (10 mins max) and a run of 5 shows plus Tech and Dress. 

I'll have a look into all of the suggestions above, and see where I get to.