# Small Bayonet Cap

Discussion in 'The Projects Forum' started by Lightfire, Mar 25, 2011.

1. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
Hello,

May I ask if these lamps/incandescent lamp can be used in homes if there is ever a power shortage? In the Philippines, the 12 volt-type of it was rated as 5 watts so it won't produce much heat and it won't pull the battery down fast. So is it okay to use?

Once again, in the Philippines the rates of these bulbs are 12 volts and 5 watts. In others, it's 24 volts but I don't know the wattage rating of it.

Thank you.

2. ### CDRIVE Senior Member

Jul 1, 2008
2,223
99
The one on the left looks like a typical automobile lamp. If your battery can handle the drain I don't see any issue with using them.

3. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
I think so.

My battery was rated as 12 AH. so means it's producing 12 ampere per hour, right?

5 divided by 12 is 0.416666666. So the battery can lasts running the light at about 28.80000005 hours. Correct me if I were wrong. But I guess, the battery will be full drained and it will be dangerous.

Hmmm, is my ohm's law equation correct? the 5 divded by 12 or watts divided by voltage to get the ampere??? if so, yehey!

Thank you...

4. ### Kermit2 AAC Fanatic!

Feb 5, 2010
3,846
963
The .416666 is the current the lamp will need. 420 mAh PER LAMP.

Always divide the Ah of the battery by 2 to get a SAFE level of discharge. OR divide the time of discharge by 2. Either way.

Your answer was 28 hours for the 12 Ah battery. Divided by 2 it would be 14 hours until the battery was discharged to a minimum SAFE level(50% discharge) for this one lamp.

Using a large deep cycle battery (120Ah) and ten lamps (4.2 amps per hour)

You still get the 28 hour answer. Divided by two and its 14 hours, which protects the battery from excessive discharge.

5. ### Lightfire Thread Starter Well-Known Member

Oct 5, 2010
690
21
OK.

Let's say I turned on my light at about 14 hours continuously. Is the brightness of the light is the same at last as from the beginning?

Thank you!

6. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
5 Watts/12 volts = 417mA.
With one of those lamps, you could probably go 14 hours on the battery without it getting too dim.

Here is a datasheet for a battery of similar type that you have:
http://www.batteryspace.com/prod-specs/LA-12V12.pdf