Question for Electronic Wizard

[zorgon]

Question for Electronic Wizard

If I take 2 60 watt light bulbs that run on 12 volts and have a 50 amp regular fully charged car battery

How long would those bulbs light?

Thanks

[deuem]

12v * 50 a = 600 watts  / 120 watts = 5 hours.
But the last hour wil be getting dimmer and dimmer

Change the bulbs to LEDS if you want staying power.

[robomont]

I agree with deuem.usually though.unplug the battery after five hours and let it set a while.there will be some residual to use .

[astr0144]

Its some time since I thought about Electrical....working out of Power, Volt Current Formula's.

Would this be correct

Power (P) (Watts) = Voltage (Volts) (V) X Current (Amps) (I)

P = V X I     or    P  = ( Volts X Amps )

600     (Watts)     = 12 V   X   50 Amps

Each Light Bulb = 60 Watts

Total Power of Bulbs If in series  = 2 x 60 Watts = 120 Watts.

Total Power of Battery = 600 watts / power used in 2 bulbs = 120 Watts

Time Bulbs will last =  Total Power Of Battery / Power used in 2 bulbs.

5 hrs                      =         600 Watts             /      120 watts



From Ohms Law ...

where R = Resistance in Ohms...

V = IXR

I = V/R

R = V/I

[robomont]

I dont mess w ohms law much but i think thats correct.the power stuff  is correct.

[ArMaP]

If I take 2 60 watt light bulbs that run on 12 volts and have a 50 amp regular fully charged car battery

Is that 50 A/h?

[PLAYSWITHMACHINES]

5 hours, correct, probably 10 if both your bateries are 50AH each.

You can multiply that 5 times using a switching circuit like the 'overunity cap' circuit i posted.
There will be more on that later, soon as i finish up a few things

[zorgon]

Change the bulbs to LEDS if you want staying power.

5 hours  crap  I guess I will have to go LED but they are harsh white  Maybe I can put a filter over top  to diffuse the light

So lemme ask ya this....

what would I need in LEDs to get the equivalent lighting of two 60 watt bulbs?

I need to light a tent at night for shoppers and don't want to mess with propane this time

[PLAYSWITHMACHINES]

I would use compact 12v CFL's like they use in campers & emergency exit signs.

I dig them out of old scanners all the time, tube, circuit, that's it. Most of them are 6-18v so they work fine

[zorgon]

DC 12V 15W CFL Light Bulb Lamp 2700k Solar Boat Marine RV Compact Fluorescent

- 90 Lumens - Equivalent to 50W incandescent bulb

- Color Temperature - 2700k - Warm White

- Works with any DC 12V Battery or DC 12V power source

- Great for Use with Solar panels and Systems



Those may work   There is power at the food vendor area so I could run a charger during the day. I only need the light for about 3 hours a day

I have a week to figure it out

[sky otter]

what about camping laterns?....batteries, lamp oil , etc..

or those led thingies you can stick in closets ..

just thinking

[Norval]

A small quiet generator? 

[deuem]

z, no matter what lights you use, just remember you have 600 watts sitting in the battery, how you spend that 600 is up to you, 12v * 50 a = 600Watts

On your new 12 v 15w bulb   use 600w/15w = 40 hours,, 2 bulbs 20 hours ,  3 bulbs 13 hours,  4 bulbs 10 hours.  So 4 bulbs at equal to 50w = lux of 200watts vs 2 @ 60w or 120 w. Like adding a third bulb for free and more left over.

I say go with 4 bulbs and you should be happy and last all day, 10 hours. If it is too bright in the day time, unscrew a few and wait for night time, Afterall 1 should go 40 hours or almost 2 days non-stop./

[robomont]

The leds are the best and safest.you dont want a cfl busting by accident.leds are way more efficient than anything else on the market.i have an led headlamp that i use almost every night for one hour and i only charge the thre triple a's like once a month.if the lite is too harsh then point it at the tent surface and it will diffuse and give a warm glow.or get a multi colored one.like with a few blues and reds mixed in with it .like the plant types.
You could run a whole week probably on a car battery.