# COMMUNITY : FORUMS : TECH

## Battery powered 120V light bulb

I'm trying to build a steam-punk costume and wanted to use a motorcycle battery to power several edison squirrel cage style bulbs. Fortunately these blubs look better if they are dimmed, but what I'm having a problem with is a schematic and what type of transformer to use.

sort by: active | newest | oldest
Toga_Dan1 year ago

running on 1/10th their rated V? I think they'll be quite dim, and waaay below rated amps. You may need an inverter to to get some substantial voltage.

Kiteman6 years ago
You don't need a transformer to use power a bulb with DC.

The question is, do you need a resistor to stop the bulbs blowing from the high current a motorbike battery can deliver?

Anybody know what current such a bulb can take?
1 year ago

I don't know much but I do know that

Watts = Amps x Volts

so technically a average bulb takes 60-100 watts so

60= Amps x 120

60=2a

100= Amps x 120

100=1.2a

or

60= Amps x 12

60=.2a

100= Amps x 12

100=.12a

1 year ago

He's not talking about old-style filament bulbs, but "several edison squirrel cage style bulbs" that are running dimmed.

gmoon6 years ago
The filament of a 120V bulb should glow with a much lower voltage. How much glow will depend on the bulb and the voltage used. A 12V battery might be exactly right for your project.

The bulbs should be wired in parallel to the battery, so they all "see" 12 volts.

If brighter is better, you might need a pair of batteries (in series) to get to 24V...

Transformers won't work with DC. Much more complex electronics (inverter) would be required to boost the battery voltage, and safety would become an issue.

Actually, a motorcycle battery can provide significant current--not high enough voltage for electrocution, but high enough current that a "short" would burn you, or could light a costume on fire.