IC Chip LED benefits

[DanielJ]

I am looking at creating a home made wireless lamps using LEDS.

I am debating using IC chips instead of regular LEDS as I think IC chips are brighter and draw less battery.

My questions are the following:

Is if possible to get warm white IC chips that have 10,000-20,000 MCD? I am planning on using 20 LEDS for this lamp.

If so, I am guessing I need to use a battery pack to ensure longer lifer, and am wondering if y'all have any suggestions?

Finally, I am worried about shadows and the angles on the IC chips I have been looking at are at most 60 degrees. I am thinking of creation a 10 sided plastic housing unit so I can disperse the light better and am curious if y'all have any better suggestions or ideas.

Thanks,

DanielJ

 

[SemiMan]

I am looking at creating a home made wireless lamps using LEDS.

I am debating using IC chips instead of regular LEDS as I think IC chips are brighter and draw less battery.

My questions are the following:

Is if possible to get warm white IC chips that have 10,000-20,000 MCD? I am planning on using 20 LEDS for this lamp.

If so, I am guessing I need to use a battery pack to ensure longer lifer, and am wondering if y'all have any suggestions?

Finally, I am worried about shadows and the angles on the IC chips I have been looking at are at most 60 degrees. I am thinking of creation a 10 sided plastic housing unit so I can disperse the light better and am curious if y'all have any better suggestions or ideas.

Thanks,

DanielJ

Daniel,

I am not sure how to respond. I am not sure you are at the knowledge level yet to ask the questions you need to ask to get the right answers. ... wireless, but you "guess you need a battery pack" ... how else were you planning to power it? ... see where I am coming from?

It may help to better describe what you are trying to do as opposed to specific part questions. That may make it easier to get the answers you are looking for.

Semiman

 

[DanielJ]

Hi Semiman,

Thanks for taking the time to reply and willingness to help me out.

Basically, I have an old house (early 20th century) and instead of bringing in an electrician, I'd like to create battery powered LED lamp (thinking 8-10 individual warm white LEDS around a plastic octagon).

Goal is to get 250-400 lumens worth of light (15,000 MCD per LED). I am not sure if you have any suggestions on LEDS or battery size and or any other issues I need to be cognizant of, but I am pretty excited about this project and learning.

Thanks,

DJ

 

[AnAppleSnail]

It's not helpful to convert millicandela to lumens. It's sort of like trying to decipher miles per gallon into feet of elevation. Millicandela represents intensity (Like water pressure), lumens total output (Like water volume). You can have a slow flood (Floody light) or a needle-jet of water (throwy light). "Lux" is your new friend for light planning: Lumens per square meter. Your office is probably around 400 lux

250-400 lumens of light is reasonably bright. Spread very efficiently, it'll get something the size of a living room to about 40 lux. This is about like a living room. The trouble, then, is spreading light efficiently. A tiny point-source of light in the center of the room is unpleasant. Sharp-edged shadows between you and any wall usually mean you'll have shadows where you want to work. The most efficient LEDs you can get that are easy to work with this way get about 150 lumens per watt, so you want 3 to 5 watts of power at the efficient end of this project.

3 watts is pretty easy to store in batteries for an hour of runtime, or even five hours of runtime. But how many do you need? One NiMH AA stores about 2.4 watt*hours (2.4 watts for one hour, or 1 watt for 2.4 hours). One NiMH D cell stores 12 watt*hours, and so on. Car batteries aren't great for this application, but deep-discharge or hybrid lead-acid marine cells can work. They're heavy, though.

Suppose I bought a Fenix TK70 and ran it on Medium (300 lumens, 15 hours) or High (930 lumens, 4.5 hours). This light runs on 4 D cells that I could recharge each day, rotating sets or something. Now I want to spread this around the room.

I can shine the light on the ceiling for a 'ceiling bounce.' This is easy, but not especially efficient. My WAG* is that you lose about 30-40% output that way, but it does diffuse light nicely. Some home lamps waste over 50% output, which is icky to me.

 

[DIWdiver]

Lampshades are used to solve the point-source problem that AnAppleSnail points out. Most are hugely inefficient. Photographers use those silver 'umbrella' reflectors to achieve the same effect with better efficiency. If you look at the typical rectangular fluorescent ceiling light fixtures ubiquitous in office environments, they use a clear plastic textured diffusers to attempt the same result, at still better efficiency. I would think you want something on that order for your lamp. I think there are some high-tech films out now with various degrees of directionality, which can avoid (at lease reduce) wastefully sending light to the ceiling.

 

[DanielJ]

It's not helpful to convert millicandela to lumens. It's sort of like trying to decipher miles per gallon into feet of elevation. Millicandela represents intensity (Like water pressure), lumens total output (Like water volume). You can have a slow flood (Floody light) or a needle-jet of water (throwy light). "Lux" is your new friend for light planning: Lumens per square meter. Your office is probably around 400 lux

250-400 lumens of light is reasonably bright. Spread very efficiently, it'll get something the size of a living room to about 40 lux. This is about like a living room. The trouble, then, is spreading light efficiently. A tiny point-source of light in the center of the room is unpleasant. Sharp-edged shadows between you and any wall usually mean you'll have shadows where you want to work. The most efficient LEDs you can get that are easy to work with this way get about 150 lumens per watt, so you want 3 to 5 watts of power at the efficient end of this project.

3 watts is pretty easy to store in batteries for an hour of runtime, or even five hours of runtime. But how many do you need? One NiMH AA stores about 2.4 watt*hours (2.4 watts for one hour, or 1 watt for 2.4 hours). One NiMH D cell stores 12 watt*hours, and so on. Car batteries aren't great for this application, but deep-discharge or hybrid lead-acid marine cells can work. They're heavy, though.

Suppose I bought a Fenix TK70 and ran it on Medium (300 lumens, 15 hours) or High (930 lumens, 4.5 hours). This light runs on 4 D cells that I could recharge each day, rotating sets or something. Now I want to spread this around the room.

I can shine the light on the ceiling for a 'ceiling bounce.' This is easy, but not especially efficient. My WAG* is that you lose about 30-40% output that way, but it does diffuse light nicely. Some home lamps waste over 50% output, which is icky to me.

Thanks for the feedback!

What is your opinion about using D cell batteries as opposed to a 4-Cell 3.4V 4600 Mah battery pack?

Personally, I prefer the battery pack as it is rechargeable and will last longer in the long run ( I realize it only has 60 watt hrs life vs 75 of 4 D batteries).

Anyways 3 Watt sounds good so far!

Thanks again!

 

[SemiMan]

Thanks for the feedback!

What is your opinion about using D cell batteries as opposed to a 4-Cell 3.4V 4600 Mah battery pack?

Personally, I prefer the battery pack as it is rechargeable and will last longer in the long run ( I realize it only has 60 watt hrs life vs 75 of 4 D batteries).

Anyways 3 Watt sounds good so far!

Thanks again!

What are you trying to light up and what are you trying to do while that space is lit?

250-400 lumens is really not very much. With typical wall reflectivity, absorption, etc. you would be lucky to get a 10'*10' (3m*3m) space to 40lux.

To that end, 3 watts may be too little ... but we would need to know more about the space and what you are trying to do.

For reference, a single 25 watt candelabra bulb is in that 250-400 lumen range.


Semiman

 

[DanielJ]

What are you trying to light up and what are you trying to do while that space is lit?

250-400 lumens is really not very much. With typical wall reflectivity, absorption, etc. you would be lucky to get a 10'*10' (3m*3m) space to 40lux.

To that end, 3 watts may be too little ... but we would need to know more about the space and what you are trying to do.

For reference, a single 25 watt candelabra bulb is in that 250-400 lumen range.


Semiman

The lighting is to make the space both functional and add ambiance.

There are two different spaces, one a 25W equivalent might be perfect (5' X 8' space), the other would need close to 40W (12' X 6').

Now, I am realizing that it will be difficult to get to 40W and have a battery supply that can last longer than 8 hrs.

For either of these options, any suggestions on LEDS or battery sources?

Note: I can take a photo of the space and upload it, if that would help.

Thanks again!

Daneil

 

[DanielJ]

UPDATE:

I bought 50 1Watt LED's that have 80-90 lumins.

I am purchasing 12V 4800 Mah rechargable battery pack to use as a power source (also getting resistors!).

I am hoping that 2-3 LEDS will be enough light.

 

[hiuintahs]

Hi DanielJ,

Since you are using resistors, try to get as many LEDs as you can in series before you exceed the forward voltage drop of the LEDs. That way you won't waste too much power in the resistor.

Here's an example. Say the forward voltage drop of the LEDs are 3.25v. 3 of them in series is 9.75v. That means 2.25v will be dropped across the resistor. If you want to run 350mA through them, then (12v-9.75v)/ 0.350 = 6.42 ohms. Power through the resistor is I squared x R = 0.786 watts. Make sure that your resistor is at least 1 watt and preferably 2 or 3 watt for reliability. power through the LED's will be 3.41 watts. Total power out of the battery will be 12v x 0.350a = 4.2w. The resistor is eating up 18.7% of the power.

With a linear approach as this without current regulation, then as the battery voltage drops so does the light output. Just so you are aware.

 

[DIWdiver]

Definitely the rechargeable pack is better, whether LiIon or NiMH. Alkalines suck at higher power levels, and the voltage drops far too much over lifetime. They're only good if you want to throw a light in the drawer for a year or three, then expect it to work well. And newer rechargables can even do that. Plus, after some charge cycles, the rechargeables pay for themselves by comparison.

3 LEDs at 80-90 lm each is not quite as much light as a 25W bulb. Also, it won't have anywhere near as uniform omnidirectional light distribution. That might be good or bad, depending on where the light is with respect to the area you are trying to illuminate. You may find you need two strings to get the light you want.

 

[DanielJ]

Definitely the rechargeable pack is better, whether LiIon or NiMH. Alkalines suck at higher power levels, and the voltage drops far too much over lifetime. They're only good if you want to throw a light in the drawer for a year or three, then expect it to work well. And newer rechargables can even do that. Plus, after some charge cycles, the rechargeables pay for themselves by comparison.

3 LEDs at 80-90 lm each is not quite as much light as a 25W bulb. Also, it won't have anywhere near as uniform omnidirectional light distribution. That might be good or bad, depending on where the light is with respect to the area you are trying to illuminate. You may find you need two strings to get the light you want.

The LEDS that I am using have a 180 degree angle, so I am hoping the light is dispersed more omnidirectional. I know it wont be to a light bulbs standards but I am hoping to have 360 degrees of illumination.

I am also planning to construct a plastic geometrical pentagon to attach the LEDs to in hopes of avoiding shadows and getting even light.

With the light output, I will test first with one battery pack first, and see if we need to increase it to two and up the LED lumens/wattage.

Thanks again for the advice.

DanielJ

 

[DanielJ]

Thanks for the info.

I am planing to wire three in series just as you stated.

Right now I am estimating the battery life to be 57.6 watt/amp hours (12v X 4800mah).

At 4.2w then I am looking at powering the lamp for about 14 hours.

Could you verify that my math is correct? I understand that this is best case scenario and it will probably be more like 10-11 hrs.

Thanks,

DanielJ

 

[DIWdiver]

Your math is correct, but your reality check is probably pessimistic. Since there is nothing sapping efficiency except the resistor, and that's already calculated in, and the load on your batteries is very light, you should expect to get pretty close to and possibly even more than the 14 hours. It depends on how good your batteries are. Lots of the cheapos don't come anywhere close to the claimed rating. Most of the better ones are close.

The other thing is that there won't be any sudden 'end' of life unless you let it run until the battery protection circuit kicks in. What will happen is that the light will get dimmer and dimmer until you decide it needs a charge. That could happen well beyond 14 hours, because as the charge runs down, your current drops. It will drop pretty low before the protection circuit shuts you off, and the discharge is slowed dramatically.