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,

    [​IMG]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? :D :D

    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
    3,772
    931
    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
    22,182
    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
    You will need Adobe Reader, or other Adobe .PDF viewer to see it.
    On the top of page 2 is shown a plot titled "BP12-12 Battery discharge characteristics"
    With a 600mA load, a light will be about the same brightness for the 1st 2 hours.
    By the time 10 hours has gone by, a 600mA light will start becoming dimmer.

    Since your 5w bulb is only drawing about 69% as much current, you should be able to operate the bulb for 14 hours without damaging the battery. You must re-charge the battery fully as soon as possible.
     
  7. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Perhaps a low power comparator and Sonalert would be prudent to protect the battery from excessive and damaging discharge.
     
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