Help Spec'ing A Battery

[Syphilis]

Dear Control Booth,

I've a problem as old as time itself: I'm designing a car-prop, and need some help spec'ing out a battery. The prop is a car bumper bolted to a support plank and some handles. Also bolted on are two 500w Par56 cans, with edison out. The plan is to twofer the cans to a switch, and hook that switch up to a battery. I've done the calculations for the battery, but I'd love a second opinion from you fine folks.

During the show, both 500w lamps will need to be on for about 10 min. During tech I don't expect for them to be on for more than 1 hour between charges.

My price range is 20-50$, and that seems to put me in favor of Lead Acid over Gel Cell.

Any thoughts would be greatly appreciated. Thanks!

 

[JD]

Why not just use good old fashion sealed beam headlight bulbs? 55w 12v [HASHTAG]#6014[/HASHTAG]. Two would be 110 watts, at 12 volts = 9.16 amps, grab a lawn tractor battery (~ $30) at pep boys. Bulbs are about $7 each.
http://www.speedwaymotors.com/12-Vo...&CAGPSPN=pla&gclid=CJj9t-mzjr8CFXMR7AodryoArw

at 7 inches, should drop right into a 56 can.

 

[epimetheus]

Dear Control Booth,

I've a problem as old as time itself: I'm designing a car-prop, and need some help spec'ing out a battery. The prop is a car bumper bolted to a support plank and some handles. Also bolted on are two 500w Par56 cans, with edison out. The plan is to twofer the cans to a switch, and hook that switch up to a battery. I've done the calculations for the battery, but I'd love a second opinion from you fine folks.

During the show, both 500w lamps will need to be on for about 10 min. During tech I don't expect for them to be on for more than 1 hour between charges.

My price range is 20-50$, and that seems to put me in favor of Lead Acid over Gel Cell.

Any thoughts would be greatly appreciated. Thanks!

First issue I see with your plan is that you're missing an inverter. If your prop is using 500W PAR56's with "Edison" plugs, then they're most likely 120V lamps. You would need one heck of a battery system to power those without an inverter. Take JD's suggestion and go with some 12V lamps. I'd try to find some LED ones if possible to save on battery drain. Also, I'd lose the Edison connectors. Even if for a one time prop, that's just asking for someone to plug them into a 120VAC circuit.

 

[Syphilis]

Thanks folks!

Thank you, JD, for the lamp recommendation, they seem like the way to go.

 

[jstandfast]

The lo-vo lamps won't have the mini edison. They'll have screw terminals.

 

[kicknargel]

And in case you're not familiar - to spec the battery (once the voltage of the battery and lamp matches) you calculate the amps of you lamps x the number of hours you need them to burn, and that's how many amp-hours you need on your battery. Leave yourself headroom, as the battery ratings are probably best case scenario in a lab.

 

[WooferHound]

Two 500w lights is 1000 watts which is 8.5 amps at 120vac.
When using an inverter to make 120vac from 12vdc the amp drain on the battery is multiplied 11 times.
So the 8.5 amps to run the lights on 120v becomes 93.5 amps coming out of the 12v battery to power it properly
To run this for one hour is a 100 amphour battery. You would need to take this up to about 200 amphours if you don't want to harm the Lead Acid battery by discharging it below 10.5 volts.
A normal car battery is 35 to 55 amphours