Don't forget that, if he's using a 9V battery the voltage will quickly decay to below 8V so I wouldn't worry about the 12mW of extra power dissipation for very long.

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Then four 2V red LEDs in series won't be lighted for long.

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Uncle $crooge

 

A 9V battery usually has around 300ma of power, so I generally only use them for single LED displays, or for large ones for brief uses. I would stick to AA or even AAA. A single NIMH AAA Battery has up to 900ma of power, so technically you could grab a few of them and make your own 7.2V battery.

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MechTronics

World of Warcraft is a disease

 

No it doesn't. A 9V alkaline battery can deliver a current od 6.7A for a few moments when it is fresh. So its power is 9V x 6.7A= 60.3W.
It can deliver 25mA for 20 hours when its voltage has dropped to 6V so its capacity is 500mAh.

The capacity of AAA cells are double the capacity of a 9V battery.
The capacity of AA cells are 5 times the capacity of a 9V battery.

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Uncle $crooge

 

Wow then I am getting ripped off on my 9V!

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MechTronics

World of Warcraft is a disease

 

Quote:

A 9V alkaline battery can deliver a current od 6.7A for a few moments when it is fresh.

It'll deliver 9V or 6.7A, not both. Available power is more like 10-15W.

 

That is correct. It gives 6.7A into a very low resistance load or into a short.

Energizer have datasheets for all their batteries. Their 9V alkaline battery has six AAAA cells inside. Their internal resistance is 0.225 ohms each when new. So the 9V battery has an internal resistance of 1.35 ohms.
9V/1.35 ohms= 6.7A. The power is 9V x 6.7A= 60.3W. The power into a 1.35 ohm resistor is 15W for a moment.
Energizer's White Paper says that some little 9V batteries have an output of 10A.

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Uncle $crooge

 

We all got a notification of a reply to this thread from hckr69.
His latest reply explained that he has a masters degree in Electrical Engineering for 20 years and has 15 years of experience working with integrated circuits and LEDs.
Then he deleted all his replies in this thread!

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Uncle $crooge

 

Goodbye to him then!

__________________
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Are you saying he posted this notification in this thread, and then deleted it? Damn strange!
He seemed like a bright guy, but he came across as a little arrogant, and that combined with his erroneous info pretty much shot his credibility to hell. Too bad.

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Ron (aka Rube)

 

I read it too.

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Publish your web page

 

It is amazing that we can read a person's thoughts (hckr69) on an e-mail then it is deleted from the forum.

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Uncle $crooge

 

I got no e-mail notification, but I read it on this thread.

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