Key light mod 2 vs 3 battery
03-08-2003, 09:36 AM
#1
Burning Brakes
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Key light mod 2 vs 3 battery
To all that have done this mod,,,,,,,,,,,,,,,,,,,(I used 2 batteries with the white 1100 mcd)Please post the led you used, and if 2 or 3 batteries? What are the brightest led avail that will work ? If you used 3 are they working ok? Not too hot by giving them 9v? I wonder if they will hold up over a peroiod of time. Let us know.
Thanks
Thanks
03-08-2003, 11:55 AM
#3
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OK...Just checked with our electronics engs. at work as they are much smarter than me when it comes to this stuff. The LEDs have a max amperage where any more current will actually mean less light, I think they said that was near 40mA. The LED can saustain bursts of up to 1A, but it is not needed and will just drain the batteries faster.
Use the 2 batteries with a resistor to limit the current to 35mA and you will be fine. Since this was only finished on my key this week, I have no actual battery life data. The CR1220 is rated @ 40mAh. My set up is drawing roughly 35mA so the battery should last 1.14hrs of continuous use.
HTH
Use the 2 batteries with a resistor to limit the current to 35mA and you will be fine. Since this was only finished on my key this week, I have no actual battery life data. The CR1220 is rated @ 40mAh. My set up is drawing roughly 35mA so the battery should last 1.14hrs of continuous use.
HTH
03-09-2003, 01:15 AM
#6
Three Wheelin'
Will having the resistor make the led (not me) less bright? I also have 3 batteries but didn't see as much improvement from adding the 3rd one as I did when I used 2 vs 1.
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03-09-2003, 01:46 AM
#8
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To determine the proper resistance for an LED with a given ANY battery voltage.
E=I/R
R=E/I
R= (Vled -Vbattery)/ I Led
Lets say you know the following from the spec sheets.
V LED typ = 3.0 V
I Led max = 30 Ma
So to stay under the max we set I LED =20Ma=0.02A
And you want to supply a battery voltage of say 6 Volts.
R= (Vled-V battey)/0.02A
R= (6-3)/0,02
R= 150 ohms
And watch the units in the specs. 9000 mcd in one spec is the same as 9.0 cd in another.
E=I/R
R=E/I
R= (Vled -Vbattery)/ I Led
Lets say you know the following from the spec sheets.
V LED typ = 3.0 V
I Led max = 30 Ma
So to stay under the max we set I LED =20Ma=0.02A
And you want to supply a battery voltage of say 6 Volts.
R= (Vled-V battey)/0.02A
R= (6-3)/0,02
R= 150 ohms
And watch the units in the specs. 9000 mcd in one spec is the same as 9.0 cd in another.
03-09-2003, 01:55 AM
#9
Nordschleife Master
Look, I'm no electrical engi-muh-neer or nuttin'
but I hooked up one of them there 3.6v LEDs, to a pair of 3.0V lithium batteries, and they was brighter than when I used a resistor with 'em. (The LED package said to use a resistor, but I tried without, and it was brighter...)
So there... take from that what you will.
BTW, I've been using the thing constantly for the past week, and it's still bright as the sun.
but I hooked up one of them there 3.6v LEDs, to a pair of 3.0V lithium batteries, and they was brighter than when I used a resistor with 'em. (The LED package said to use a resistor, but I tried without, and it was brighter...)
So there... take from that what you will.
BTW, I've been using the thing constantly for the past week, and it's still bright as the sun.
03-09-2003, 01:57 AM
#10
Nordschleife Master
just found this hooey on that there website:
LEDs do not have resistance like a resistor does. LEDs have a dynamic resistance, that is their resistance changes depending on how much current passes through them. But it's easiest to think of them as having NO resistance. This means that if you just connect an LED to a battery, you'll have a short circuit. That's bad. You would probably ruin your LED.
I'll let ya'll know when my LED dies...
LEDs do not have resistance like a resistor does. LEDs have a dynamic resistance, that is their resistance changes depending on how much current passes through them. But it's easiest to think of them as having NO resistance. This means that if you just connect an LED to a battery, you'll have a short circuit. That's bad. You would probably ruin your LED.
I'll let ya'll know when my LED dies...
03-09-2003, 02:03 AM
#11
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I connected a 3.6V led to a 9v batteries before. I think lasted about a minute and a half before burning itself out. In comparison I think most leds are rated with a mean time to failure measured in years, not minutes.
edit: wow... yea... I found one led with a MTBF rate of 121,358 years. Well, if I calculated it right. Its failure rate was 0.00047 per 1,000,000 hours (114 years).
edit: wow... yea... I found one led with a MTBF rate of 121,358 years. Well, if I calculated it right. Its failure rate was 0.00047 per 1,000,000 hours (114 years).
03-10-2003, 09:41 AM
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Hows this for an under-edumacated question. If LEDs are 3v min, and 4.5v max - why not stack a 3v with a 1.5v? I got to thinking about all the series cells I've ever seen though, and couldn't find a single instance where all cells weren't the same so there's probably an issue.
I'm going to hit a Batteries Plus this afternoon to see what they can help me work out. Since noone's posted a 3v battery the fits the key - I imagine one doesn't exist, but I'm going to look.
I'm going to hit a Batteries Plus this afternoon to see what they can help me work out. Since noone's posted a 3v battery the fits the key - I imagine one doesn't exist, but I'm going to look.