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battery powered light bulbs? Answered

Will a 12 v battery power a 12 v bulb (23A alkaline batteries, 6S6?12V - 6 Watt bulb), and for how long? Also same question w/a (6 Volt - 5.0 Amps - S8 Bulb, Alkaline Battery 6V A544 4LR44 PX28A battery)?

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AlbertP54

2 years ago

You should try Xenons4U.co.UK, Super bright LED bulbs best for your car.

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MichelleH160

2 years ago

Ok, I should have given details about what I am trying to do. I am making some steam punk copper candle holders but at the last minute the fire marshall said no candles. So, I thought light bulbs would be great but I am not stringing cords all over the event space so they would have to be battery powered. I've tinkered with wiring led bulbs to batteries before but clearly do not have a good understanding of electricity. I want a traditional edison type bulb (but could be any size or shape - the copper pipe is 1/2 inch and 3/4 inch) and need to wire each bulb to a battery. I'm making a lot (between 24-30 bulbs and batteries) so obviously, the cost must be very low (like $1-$2 max a piece). Any ides/solutions?

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kelseymhMichelleH160

Answer 2 years ago

Look at "LED tea light" on Amazon. The first hit was for a dozen of them for $13, and a couple of lines down was two dozen for $10. You should be able to easily strip the bulb/battery combo out of the stupid plastic mold, and put them into your own candle holders. Good luck!

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rickharrisMichelleH160

Answer 2 years ago

Your going to have a real difficulty getting low voltage bulbs suitable for battery use. pretty much the only source is going to be bicycle light bulbs, or even motor bike or car bulbs.

The motor bike or car bulbs expect 6 or 12 volts and will be 4 to 8 watts so watts = Amps x volts so 4/12=0.3 amps 8/12=0.6 amps. You will be able to run these from an RC lipo or a set of 8 D type cells to get a reasonable battery life. The RC lipo battery will give you the biggest energy density ie. it will be the smallest for the amps it can supply.

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Jack A Lopez

2 years ago

Wikipedia has a list of battery sizes, in an article titled, uh, "List of battery sizes"

and most of the batteries you mention are in this list, in the table for
https://en.wikipedia.org/wiki/List_of_battery_size...


Every bulb+battery match you have suggested seems like a bad match to me.

The reason why I think what you have suggested won't work is based on a simple two-step formula.

(1) First I divide the current capacity (in ampere*hours) by the expected load current (in amperes), to get an estimate for battery life (in hours).

(2) I compare that amount of time to 1 hour. If the lifetime estimate is less than 1 hour, then I conclude this bulb and battery are a bad match. The reasoning behind this comparison is the quote given for current capacity, usually assumes a discharge time much longer than one hour. In other words, I am guessing any discharge rate faster than the 1 hour rate is way too much current for that size battery.


Example 1: The A23, a nominal 12-volt battery, has current capacity 55 mA*h. A 6 watt bulb wants 500 mA. So the battery life estimalte is (55 mA*h)/(500 mA) = 0.11 h. This number is a lot less than 1 hour, so this is a bad match.

Example 2: The 4LR44, a nominal 6-volt battery, has current capacity of about 150 mA*h. If the bulb wats 5 A = 5000 mA, then the battery life estimate is (150 mA*h)/(5000 mA) = 0.03 h, so this is a bad match too.

You know, if you want to make an itty-bitty flashlight, there exist white-LED flashlight bulb modules. Usually these are made to run from one or two alkaline cells, with power consumption around 0.5 W. E.g. (2.5 V)*(200 mA) = 500 mW

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iceng

2 years ago

How Dim will you accept the Bulb to be under power ??

It may be a surprise, but alkaline batteries drop in voltage as they discharge..

Ergo, the bulb intensity will diminish with time...

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rickharris

2 years ago

Your batteries should be marked with an Amper/hour rating this is how much current the can supply for an hour.


Watts is Amps x Volts so you can work out the current a 6 watt bulb draws at 12 volts.

As a general guide I know a car battery - often around 50 to 70 Amper hours will power an 80 watt car headlight bulb for about 5/6 hours reasonably brightly and for a few more hours with decreasing brightness.

My 1,000,000 candle power halogen lamp will rum off a 6 volt 4.5 A/hr lead acid cell for about half an hour. It's about 50 watts.