Re: LEDs - Simple Wireing Questions

From: Roger Johansson (no-email_at_home.se)
Date: 11/04/04 

Date: 4 Nov 2004 01:43:41 GMT

John Popelish <jpopelish@rica.net> wrote:

> Saying that the batteries are 3 amps each is a bit nonsensical.

Maybe a fire extinguisher could be a good analogy for a battery.

It can deliver a certain amount of liquid and the pressure is high if it
newly filled.

If it contains 10 liter of water it can deliver a current of 1 liter per
second for 10 seconds. But the flow is not constant through these 10
seconds, the pressure and the current is a little higher in the beginning
and slows down as it becomes emptier.

There is a certain flow resistans in the output tubes and stuff, and that
limits the flow somewhat.

A battery has a capacity rating, like the amount of water in the fire
extinguisher, it is measured in AmpereHours (Ah) or mAh for smaller
batteries.

A battery with a capacity of 3000mAh can deliver 3000mA for one hour, or
1000mA for 3 hours, or 100mA for 30 hours.

Batteries also have a voltage rating, like the water pressure in the fire
extinguisher, it is measured in Volt.

The amount of work a battery can deliver is the capacity times the
voltage. A 3 Volt battery with 3000mAh capacity can do a work of 3*3 VAh,
or 9 Watthours.

That is what you pay for when you pay the electricity bill, the work you
have bought, measured in VoltAmperehours, or Watthours, or kiloWatthours.

The effekt is how much work is performed per time unit, like Watthours
per hour, or simply Watt. 

-- 
Roger J.

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