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What mAh value does a standard 9V battery have?

Discussion in 'General Electronics Chat' started by Lac, May 11, 2004.

  1. Lac

    Lac New Member

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    I have got a white/blue LED that draws 100mA, how long would a plain, normal, standard 9V battery be able to supply enough current for the LED to light up brightly?

    And btw, what is the voltage drop over a normal led? Is the drop the same for the type of LED I've got hold of here?

    Cheers!
    Lac.
     
  2. Optikon

    Optikon New Member

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    with regards to battery capacity, you did not specify what type of chemistry your 9V battery is, and it matters.

    Since you said plain and normal, I assume it is alkaline type.

    Expect between 400 and 600 mAh. A good quality panasonic industrial type shows 570 mAh.. low end type probably more like 400.

    You should expect at least 4 hours out of your brightly lit LED.

    Typical forward drops for normal LED (for which a 100mA device is not normal) I am talking a T1 type or SMT type that runs up to around 20mA.

    Green is about 1.9V
    Blue (maybe white also - not sure) more like 2.5 - 3.5V
    Reds, ambers and similar are less than 1.9V I believe

    These are very rough numbers so consult the datasheet to be sure..
     
  3. xenoxion

    xenoxion New Member

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    Here's data based on duracell batteries... their 9V battery is rated at 580mAh.
     
  4. dave

    Dave New Member

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  5. olly_k

    olly_k Member

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    White LED's are infact blue LED's in disquise :shock: They just have a blue-sensitive phospher coating to produce the rest of the spectrum.
     
  6. JFDuval

    JFDuval New Member

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    Hi!

    If a 9V is approximatly 600mAh, can you tell me what for a AA? and for a AAA ? Also, is the difference big between a alkaline 9V and a carbon 9V ? Thanks in advance,
     
  7. Crofty

    Crofty New Member

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    AA's are 2700mAh. AAA's are 1175mAh (assuming Alkaline)

    An alternative for your White LED's drive, try 3x1.2V Nicads/NiMh, this gives 3.6V. which is ideal for white leds ;) NiMh's are available upto 2300mAh.

    Even more sneaky, use One Nicad with one IC. ie: MAX1678. This gives a fixed 3.3V o/p @45mA (one Cell) or, 3.3V @90mA (2 cells)

    Steve
     
  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Zinc carbon batteries are really useless, have a look at these discharge graphs I plotted many years ago using two AA's and a 200mA bulb http://www.lpilsley.com/viewbatt.htm.

    Notice that two Duracell AA's last about 8-9 hours at 200mA.
     
  9. JFDuval

    JFDuval New Member

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    Hi! Your link doesn't work...
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    If you mean my link, I just tried and it worked fine?.

    Try http://www.lpilsley.co.uk/viewbatt.htm and see if that works for you!.
     
  11. JFDuval

    JFDuval New Member

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    Hi! Now it's ok. I suppose that the Panasonic High Power is a carbon one?
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Yes, all it said on the casing was 'High Power', but you can instantly tell from the shape of the discharge graph - useless aren't they!.
     
  13. JFDuval

    JFDuval New Member

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    Yes, they are!
     
  14. JFDuval

    JFDuval New Member

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    Yes, they are!
     
  15. JFDuval

    JFDuval New Member

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    Yeah, It's really useless. No cash to save their.
     
  16. pike

    pike Member

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    those "high power" batteries sicken me!!, it's these kinds of batteries that are falsely marked.

    I wonder how the metal hydride types would match up???
     
  17. spuffock

    spuffock Member

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    And if you think you can get away with it because your project only draws 50ua, then the damned things leak and everything corrodes. :evil:
     
  18. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Yes, always use alkaline batteries! - normal ones just leak and destroy things. I've just had a Sony CD/Radio/Cassette brought into work, under warranty! - he's let the batteries leak everywhere, it's full of nasty corrosive liquid - totally destroyed!. As you can well imagine, this is 'customer misuse' and not covered by warranty!.
     

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