White Nichia on 3V?

[BillBill]

Has anyone used a single 2032 cell in a 2x2016 coin cell light? If so, is it enough to power a LED? How long will the battery last? I'm planning to use a 2032 in my white Inova Microlight.

 

[drs2000]

I've installed CR2032s in white squeezelights before. Depends on the LED more than anything else, but the two I tried ended up giving about an original Infinity's worth of bright. Haven't left one on a long time yet, tho. I've been using a newer version of a Nichia clone, running as a dime but useable nightlight. It's getting tired now, but it's been running every night for over a month at about 1ma current.

You'll probably get well over 4x the life of 2 cr2016s, and maybe as much as 10x, depending on current/VF/light output.

Can't hurt to try..

Yours, drs the crazed.

 

[BillBill]

How much is an "original Infinity's worth of bright?" I'm a newbie.

 

[drs2000]

Sorry about that. My bad. The Infinity was one of the early 1 AA lights, that ran for days, but wasn't very bright. Again, at those voltages, your best bet is to go ahead and try it with your version of the keychain light. (Check Batterystation CPF supporter for inexpensive CR2032s.)

You could read by the Infinity, or use as a nightlight in a hotel, for example. But your newer squeezelight stomps the snot out of it for brightness on 2 CR2016s. For minutes, anyway. after 1/2 hour or so... The Infinity keeps on, the squeezelight poops out.

If you've only got CR2016s that are still good, you can try the LED on just one of them. It'll give you the brightness of the 2032 for testing.

Good luck and hope you like it here..

Drs the crazed..

 

[BillBill]

I'm sorry for being so abrupt on the reply. Thanx for the opinion. I'll just need a 2032, not ten. So, i'll pick one up one at Frys for $1.29 or something. BTW, the 2016's in my light are not good. I've tried using one of them and the LED puts out a faint glow. Heck, with two bad 2016s, the Microlight isn't too bright. Thanx, I will try a single 2032 because i "use" my lights a lot (instead of standard incandescent lighting).

 

[gwbaltzell]

I ordered some white Nichias a while back and was surprised when I measured the drop voltage at 3.2V. Current draw was almost a perfect 20ma from a fresh lithium cell and was around 5ma and putting out a fair amount of light on a cell I considered at near end of life.

George

 

[Doug Owen]

FWIW, a useful option in trying to drive white LEDs from 3.0 Volts is to drive several LEDs in parallel.

Some time back I was fiddling with four in parallel on a single 123 Li cell. I got some useful results by screening low Vf (a bit under 3.2 Volts at 25 mA IIRC) LEDs from a bag of 100 I bought from Hong Kong.

If long cell life is an issue with coin cell lights, you might consider Red or Yellow (which are designed to run on the 2032 to start with). Run time is *much* longer.

Doug Owen

 

[BillBill]

Re II: White Nichia or Red/Yellow Nichia on 3V?

The responses have made me ask more questions:
Which Microlight would run longer on a single 2032: a white one or a red one? How would their brightness compare(or if they don't compare-different colors)?
I know that these are demanding questions for so simple a problem. /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/banghead.gif
BTW, is changing a subject impolite in this forum? another question /ubbthreads/images/graemlins/banghead.gif

 

[Doug Owen]

Re: Re II: White Nichia or Red/Yellow Nichia on 3V?

The red would be normal brightness while on 3 Volts the white will be very dim (and would therefore be very dim for a very long time).

I don't know the rules, but it's your topic, you shave the guy you're most likely to offend by modifying the subject....I say go for it.

Doug Owen

 

[BillBill]

Re: Re II: White Nichia or Red/Yellow Nichia on 3V?

I finally tested the Inova on a 2032. It is decently bright enough to be useful, but does not compare to other properly driven LED lights. But I like it anyway.

 

[paulr]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

You should get verry long runtime with the white led and 2032, though at that dim output level.

If you use a red or yellow led, you'll get much more brightness, and more runtime than the white with 2x2016, but less than with the dim white and 1x2032.

 

[BillBill]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

Thanks for your expertise, Paulr. /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/grinser2.gif /ubbthreads/images/graemlins/bowdown.gif

 

[BillBill]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

Hey, how did I become a flashaholic?
Double post, sorry.

 

[paulr]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

Heh, flashaholism happens to all of us. My post wasn't clear: while I haven't done measurements, I expect results with different LED's will be something like:

1x2032 white: dim output, very long runtime
1x2032 red or yellow: medium bright output, long runtime
2x2016 white: bright output, short runtime

You might try 1x2032 green for results somewhere between the white and yellow in both brightness and runtime.

One of these days I'll get around to making some actual measurements, though they will vary from led to led.

 

[gadget_lover]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

What is the brightest 5mm white? It looks to be around 7000mcd, but I'm not sure.

Sidenote... I was playing with a 2AA minimag and realized that two L91 (lithium AA cells) were about 3.6 volts. The LED is rated for 20ma, but Draws 28 ma in this direct drive mode. Think I should add a resistor?

Daniel

 

[VMamie]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

gadget_lover,

If you're using Nichia whites, I think 20mA is their Typical Forward Current, but these are rated at 30mA for maximum forward current with maximum brightness. The penalty for running at 30mA is shorter life. The lifetime rating of 100k hours is for 20mA.

 

[paulr]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

28 ma is safe for 5mm led's. You should get around 3.4 volts from that L91 pair. 3.6v may be possible if the cells are brand new but nominally they're 1.7 volts per cell. Supposedly the best Nichias are around 12000 mcd, but who cares. If you're after more brightness, use a Luxeon.

 

[gadget_lover]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

[ QUOTE ]
paulr said:
28 ma is safe for 5mm led's. You should get around 3.4 volts from that L91 pair. 3.6v may be possible if the cells are brand new but nominally they're 1.7 volts per cell. Supposedly the best Nichias are around 12000 mcd, but who cares. If you're after more brightness, use a Luxeon.

[/ QUOTE ]

Sometimes the luxeon is not the answer. /ubbthreads/images/graemlins/smile.gif

My very first LED mod was with the afore mentioned minimag. It has sentimental value. It has run on 3 N cells for several years. It looked kind of puny next to the ARC and even some other small LED lights. Just for fun I upgraded to a "new" 7000 mcd nichia and threw in the lithiums just to see what would happen. It's still not as bright as my ARC AA, but it should last a long, long time with the lithiums. It's more for show than anything else.

On the other hand, it is amazing how much light a luxeon will put out at 30 ma.

Daniel.

 

[BillBill]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

Paulr, is it true that LED's draw less current and are more efficient at lower voltages? /ubbthreads/images/graemlins/blush.gif

 

[paulr]

Re: Re II: White Nichia or Red/Yellow Nichia on 3

I don't know about efficiency, but yes, forward current decreases very rapidly as voltage decreases.