Connect with us

So, how many "watts" is a 9-volt battery?

Discussion in 'Power Electronics' started by Flurng, Aug 4, 2015.

Thread Status:
Not open for further replies.
Scroll to continue with content
  1. Flurng

    Flurng

    21
    0
    Dec 29, 2012
    Every 9-volt battery I've seen has the voltage rating printed right on it, yet none seem to list the wattage, or even amperage rating - so what gives, here?
     
  2. Minder

    Minder

    3,044
    644
    Apr 24, 2015
    Last edited by a moderator: Aug 6, 2015
    Flurng likes this.
  3. BobK

    BobK

    7,682
    1,687
    Jan 5, 2010
    The current that a battery can supply to a short circuit is not well controlled and drops rapidly with use. In other words, you might initially get 2 or 3 amps from a 9V battery, but only for a few minutes.

    The capacity rating of a battery tells you how long you can pull a given current from the battery. A typical rating for a 9V is 450mAH. Which means you can pull 450mA for one hour or 50mA for 5 hours, which is the same amount of energy.

    But even that is misleading. At higher current draws, a battery cannot supply the same amount of energy as it can at lower currents.

    Typically, an ordinary battery should not be used at higher current than the capacity, but there are exceptions. The rating is usually given to a usage of much more than one hour, often 20 hours is used.

    Bob
     
    Flurng likes this.
  4. Alec_t

    Alec_t

    2,927
    797
    Jul 7, 2015
    For 5 hours read 9 hours.
     
    Flurng likes this.
  5. Ratch

    Ratch

    1,091
    333
    Mar 10, 2013
    Watts are not a quantity that you can put into a battery. Wattage is a rate of energy transference. If you want to know how much energy is in a battery, don't ask for its wattage.

    Ratch
     
    Flurng and davenn like this.
  6. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    if its a PP3 type 9V battery, they are just a low current battery up to around 350mA continuous till voltage starts dropping
     
    Flurng likes this.
  7. Flurng

    Flurng

    21
    0
    Dec 29, 2012
  8. Flurng

    Flurng

    21
    0
    Dec 29, 2012
    Hello again, BobK! Thanks for the helpful Info, although I guess what I should have asked is, supposing a device ( transistor, LED, motor, etc...) requires 1 watt; could a typical 9 volt battery power it, and if so, for how long? In the past, I have come across "30 watt" speakers, "5 watt" motors, "1/4 watt" resistors, and so forth - I guess I'm just wondering about the maximum wattage a battery can handle.
     
  9. Flurng

    Flurng

    21
    0
    Dec 29, 2012
    Thanks, Alec_t - good catch!
     
  10. Flurng

    Flurng

    21
    0
    Dec 29, 2012
    Thank you, Ratch, for the info. I do understand the distinction, but I'm still unclear as to exactly how much "power" or energy a battery can provide. Typically, I work with standard, common 9 volt "transistor" style batteries, and I'm just wondering about the maximum power such a source can supply. For instance, I've no delusions that a 9 volt battery could power a jumbo jet, but what about a "10 watt" speaker, or a "5 watt" motor, etc....?
     
  11. Flurng

    Flurng

    21
    0
    Dec 29, 2012
    Thanks, davenn - this is exactly the type of info I'm looking for! Unfortunately, I have no idea what a PP3 battery is, or what type I'm working with - typically, I'll just grab a common alkaline 9 volt, such as a Duracell or Energizer....
     
  12. Martaine2005

    Martaine2005

    3,217
    883
    May 12, 2015
    Hi Flurng,
    The link 'minder' supplied is a PP3 9V battery. Although Duracell don't seem to say 'PP3'.

    Martin
     
    davenn likes this.
  13. Ratch

    Ratch

    1,091
    333
    Mar 10, 2013
    The amount of energy that can be obtained from any battery is determined by the rate it is de-energized. If de-energized slowly, then more energy can be extracted. There are battery manuals that give the specs of various batteries.

    Ratch
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Thread Status:
Not open for further replies.
Electronics Point Logo
Continue to site
Quote of the day

-