How much current does a 9v battery put out?

[Kelvrick]

Ditto.

I don't have a multimeter, or I'd just test it myself.

Thanks!

 

[masterxfob]

ever stick one on your tongue? hehe, don't lie, i know everyone has tried it before

 

[Kelvrick]

Of course I have. I've also converted a good number to the dark side. Bwahahahaaa

No, but I'm messing with a lighting system and I'd like to not burn out all my leds and such.

 

[masterxfob]

well, i guess you can call me an idiot, but i have no clue to the answer of your question.

just forget about the whole lighting thing and stick the battery on your tongue for old times

 

[Kelvrick]

Sigh, and all these searches on google do nothing.

The searches, they do nothing!

Oh well, guess I'll just have to gestimate it.

 

[GiLtY]

Depending on the resistance of your wire. in a closed DC loop, the Voltage = Resistance * Current. So lower the resistance bigger the current.

 

[Kelvrick]

Originally posted by: GiLtY
Depending on the resistance of your wire. in a closed DC loop, the Voltage = Resistance * Current. So lower the resistance bigger the current.

JESUS!! Physics, I have failed you. V=IR, that was one of the formulas everyone should know. Thanks a lot! And I just went and already emailed energizer asking them what their output was.

 

[Lithium381]

Originally posted by: masterxfob
ever stick one on your tongue? hehe, don't lie, i know everyone has tried it before

i haven't, i'm too scared, i heard you get shocked.......though one time when i was little i grabbed an electric fence with both hands and my mom had to tackle me to get me off......maybe that explains it :Q

 

[Marshallj]

It depends on what kind of battery it is (alkaline, Nicad, NiMH).

 

[masterxfob]

Originally posted by: Kelvrick

Originally posted by: GiLtY
Depending on the resistance of your wire. in a closed DC loop, the Voltage = Resistance * Current. So lower the resistance bigger the current.

JESUS!! Physics, I have failed you. V=IR, that was one of the formulas everyone should know. Thanks a lot! And I just went and already emailed energizer asking them what their output was.

lol, i don't think the csr that received your email would even know that

 

[So]

Originally posted by: Kelvrick

Originally posted by: GiLtY
Depending on the resistance of your wire. in a closed DC loop, the Voltage = Resistance * Current. So lower the resistance bigger the current.

JESUS!! Physics, I have failed you. V=IR, that was one of the formulas everyone should know. Thanks a lot! And I just went and already emailed energizer asking them what their output was.

[nelson]Ha HA![/nelson]

gIlTy...beat me to the punch.

 

[Kelvrick]

Well, it doesn't matter. Guess I'll be picking up some 200ohm resisters tomorrow at radioshack.

Thread got more replies then I thought. Me going to bed now.

 

[masterxfob]

Originally posted by: Lithium381

Originally posted by: masterxfob
ever stick one on your tongue? hehe, don't lie, i know everyone has tried it before

i haven't, i'm too scared, i heard you get shocked.......though one time when i was little i grabbed an electric fence with both hands and my mom had to tackle me to get me off......maybe that explains it :Q

ish....did the skin on your hands melt? my dad, being the handy man that he is, had a similar experience where his skin started to melt. he was kinda cool, he had a purple hand/wrist for a while

 

[masterxfob]

Originally posted by: Kelvrick
Well, it doesn't matter. Guess I'll be picking up some 200ohm resisters tomorrow at radioshack.

Thread got more replies then I thought. Me going to bed now.

g'night son

 

[Marshallj]

Originally posted by: Kelvrick

[/i]
JESUS!! Physics, I have failed you. V=IR, that was one of the formulas everyone should know. Thanks a lot! And I just went and already emailed energizer asking them what their output was.

A battery does not have infinite supply though. Although the electrical equation may make it look like it could draw a lot of amps, the battery may not have the ability to provide that much current with the chemical reaction taking place inside of it.

 

[Marshallj]

Originally posted by: GiLtY
Depending on the resistance of your wire. in a closed DC loop, the Voltage = Resistance * Current. So lower the resistance bigger the current.

That only works up to a certain point. If you do the equation and put in no resistance (such as a short circuit), it would say that the current draw is nearly infinite. But the battery will not be able to put out that much current.

Let's say he's designing a circuit and he does the equation and find out that it will draw 5 amps. When he plugs the 9v in, the circuit won't work right. Why? Because the battery won't produce that much current. Even with a dead short it will have a upper limit of how much current it can provide.

 

[Marshallj]

Originally posted by: Kelvrick
Of course I have. I've also converted a good number to the dark side. Bwahahahaaa

No, but I'm messing with a lighting system and I'd like to not burn out all my leds and such.

Oh, I didn't see this before (damn)

For LED's, they don't draw much juice.

Consult this handy utility:



This comes in handy when designing LED circuits

 

[TuxDave]

If you're looking for maximum output current, I believe it should have a maximum output power spec on the battery, and using P=IV, that should answer your question. But then again, I'm only guessing

 

[So]

Originally posted by: Marshallj

Originally posted by: GiLtY
Depending on the resistance of your wire. in a closed DC loop, the Voltage = Resistance * Current. So lower the resistance bigger the current.

That only works up to a certain point. If you do the equation and put in no resistance (such as a short circuit), it would say that the current draw is nearly infinite. But the battery will not be able to put out that much current.

Let's say he's designing a circuit and he does the equation and find out that it will draw 5 amps. When he plugs the 9v in, the circuit won't work right. Why? Because the battery won't produce that much current. Even with a dead short it will have a upper limit of how much current it can provide.

That's due to the internal resistance of the battery, correct? (or is that just a fiction from high school phys?)

 

[FenrisUlf]

If you regularly read Dan's articles (www.dansdata.com) you will see that he talks about batteries ALOT. A quick search there will probably yield more info about batteries than you ever cared to know. You can probably pull a few hundred mA off of a regular 9v, but remember that they're made up of six smaller cells inside, each only a fraction of the size of a AAA. At that current draw you'll severly compromise its lifespan and might not be able to get the full 9v.

 

[DaWhim]

kiss it and feel it
lol

 

[Marshallj]

Originally posted by: So

That's due to the internal resistance of the battery, correct? (or is that just a fiction from high school phys?)

The internal resistance of the battery is one reason, and the rate that the chemical reaction (that produces the electricity) can occur is another reason. A battery is not like a capacitor where you can short it out and dump the full load, a battery can't release all of its energy at once like that. If you tried you'd probably burn it out or even make it explode. It's meant to produce the electricity slowly and release it slowly.

 

[Marshallj]

Originally posted by: FenrisUlf
If you regularly read Dan's articles (www.dansdata.com) you will see that he talks about batteries ALOT. A quick search there will probably yield more info about batteries than you ever cared to know. You can probably pull a few hundred mA off of a regular 9v, but remember that they're made up of six smaller cells inside, each only a fraction of the size of a AAA. At that current draw you'll severly compromise its lifespan and might not be able to get the full 9v.

Yup, his site has loads of info on it.

I found this in an article about a camera:

"65mA is on the high side for an alkaline 9V to deliver, and 200mA is definitely a bit mean to it. But you still ought to get more than three hours of on-time from each battery, and maybe as much as five, depending on how you use the camera. That's surprisingly good; I was expecting the Dual Cam to be thirstier."

So it's sounding like by 200ma you're really starting to push a 9v battery.

 

[Marshallj]

Originally posted by: So

Originally posted by: Marshallj

Originally posted by: GiLtY

That only works up to a certain point. If you do the equation and put in no resistance (such as a short circuit), it would say that the current draw is nearly infinite. But the battery will not be able to put out that much current.

That's due to the internal resistance of the battery, correct? (or is that just a fiction from high school phys?)

Ok, I found some specs and played with the numbers. An alkaline 9v battery has an internal resistance of about 2 ohms. With a voltage of 9 volts and an internal resistance of 2 ohms, if we were to run a the battery in circuit with an LED on it (around 1 ohm), according to the formula the expected current flowing in the circuit would be 3 amps. But it's doubtful that a 9v will be able to produce that kind of current, for the reasons I mentioned above.

 

[Eli]

You aren't going to be able to run an LED on a 9v without some other circuits to limit voltage/current.