What is the voltage rating of lamps on a parallel circuit with a 12 volt battery?

Answer 1

If the lamps (the technical term for light bulbs) are the "correct" ones, the 12 volt battery is all there is and all the lamps are connected in parallel, the lamps are rated at 12 volts. There are a flock of assumptions, but why not pick an easy example to make a case? The average vehicle has a 12 volt electrical system. Car people throw that number around all the time. But the actual voltage on the power buss when the engine is running is in excess of 13 volts because of the alternator that keeps the battery pumped up and runs the electrics. All the lights on the rig (and they're all connected in parallel) are run off the 12 volt buss. Ask an auto person what a light bult for a car is rated at and the answer may very well be "12 volts" (the normal expression of the buss voltage). Could it be said the lights are rated at 13 volts (or 14 volts) because that's the actual working voltage of the system with the engine running? Sure. Why not. Whatever works. The lights will work at a higher voltage (15 volts) , but they will be far more susceptable to damage by vibration and shock. And they will certainly have a shorter life if the voltage is ramped up. Keep it simple and say that lamps designed to work in a 12 volt system are rated at 12 volts. Don't go into an auto parts store and ask for a lamp rated at 14 volts. You'll probably just confuse the parts helper. The folks who make the light bulbs know the drill, know the normal range of voltages over which the light will be working. They'll optimize their designs to produce fairly priced but well-performing pieces that stand up nicely over a modest range of voltages. And that includes some voltages a bit above the actual "rating" of the lamp.