x2x3x2
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If i have an led with 20mA optimal operating current.
Does is mean it used 20mAh?
Does is mean it used 20mAh?
mAh conversion
- Thread starter x2x3x2
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LedSled
Newly Enlightened
mAh is milliAmp-hours, current multiplied by time. Direct-drive your LED at 20mA for one hour and you've drawn 20mAh from your battery.
billw
Enlightened
LedSled said:
Doesn't "direct drive" usually mean with no current limiting resistors or ANYTHING?
That makes it pretty hard to pick a drive current; you have to be "lucky" to fall into the
region where the LED won't blow up (seems to happen with Li coin cells and 20mA LEDs,
or several battery combos and luxeons.)
Better to say that a 100mAH battery pack, with appropriate current limiting, will drive
a 20mA LED for about 5 hours...
BillW
LedSled
Newly Enlightened
Billw, you're right, of course. The only reason I said "direct-drive" is that switching regulator circuits will feed the LED at a different current level than that being drawn from the battery, sometimes quite different. Since mAh ordinarily applies to the battery, it's the battery current that is of interest.
Direct-drive, direct-drive with series resistors, and (less a small operating overhead) series-pass regulator circuits, will all feed the LED with the same current as drawn from the battery.
Direct-drive, direct-drive with series resistors, and (less a small operating overhead) series-pass regulator circuits, will all feed the LED with the same current as drawn from the battery.
