Uh oh, this time I read the data sheet. Look again. This LED actually DOES use 100mA continuous, and this is much more in line with typical IR LEDs.

Did I mess up again???
I see where you are in the first chart, but the second chart seems to contradict that.
Then the graphs seem to confirm it.
Yep. My bad.
1.3V x .1A = .13W
Entirely reasonable.

Lots more factors to consider.
Page 4, 100ma only when not above 25C.
Page 4, Vf avg =1.4 volts @ 100ma
Page 5: 4x the intensity for 5x the current. (efficiency loss)
Recover that loss by using exactly 5 LEDs @ 1.4V
(8.2V -7V)/.1A
R= 12 ohms.

I tend to think, 2 strings at 50 ma so they will be safe at 60C (caused by sitting in the truck all morning, then self heating added in).
5 LEDs at 1.35Vf = 6.75V
8.2 - 6.75 = 1.45V
1.45V / .05A = 29 ohms. Buy 30 ohms.
(and don't you dare make it 6 LEDs and try to calculate a resistor for .1 volt!)

Gosh this running long for an LED thread!

It looks like wayneh and I have come to a conclusion. 2 batteries in parallel driving 2 strings of 5 at 50 ma each.

and I have a chore to run. More than an hour to get back home.

 

Did I mess up again???
I see where you are in the first chart, but the second chart seems to contradict that.
Then the graphs seem to confirm it.
Yep. My bad.
1.3V x .1A = .13W
Entirely reasonable.

Lots more factors to consider.
Page 4, 100ma only when not above 25C.
Page 4, Vf avg =1.4 volts @ 100ma
Page 5: 4x the intensity for 5x the current. (efficiency loss)
Recover that loss by using exactly 5 LEDs @ 1.4V
(8.2V -7V)/.1A
R= 12 ohms.

I tend to think, 2 strings at 50 ma so they will be safe at 60C (caused by sitting in the truck all morning, then self heating added in).
5 LEDs at 1.35Vf = 6.75V
8.2 - 6.75 = 1.45V
1.45V / .05A = 29 ohms. Buy 30 ohms.
(and don't you dare make it 6 LEDs and try to calculate a resistor for .1 volt!)

Gosh this running long for an LED thread!

It looks like wayneh and I have come to a conclusion. 2 batteries in parallel driving 2 strings of 5 at 50 ma each.

Thanks again for all this help. So using this updated setup there will be a 2 x 5 array of LEDs in conjunction with 2 9V LiMnO2 batteries. If I am correct, increasing the number of strings within this array will still allow it to function but at a reduced total power length. The temperature range that this array will be generally be exposed to is in between 0-40 degrees celsius so it would allow for a larger range of LEDs to be used.

 

You could also drop to 1 battery and 1 string of LEDs and get the same time duration as 2 batteries and 2 strings of LEDs if size is important.

The temperature range has already been considered. I don't know what that has to do with, "a larger range of LEDs". Are you planning on buying different LEDs?

ps, NOW we can work with a 12V 2AH battery. What kind? Lead acid, Lithium, NiMH?

 

You could also drop to 1 battery and 1 string of LEDs and get the same time duration as 2 batteries and 2 strings of LEDs if size is important.

The temperature range has already been considered. I don't know what that has to do with, "a larger range of LEDs". Are you planning on buying different LEDs?

ps, NOW we can work with a 12V 2AH battery. What kind? Lead acid, Lithium, NiMH?

What I meant by "a larger range of LEDs" should've been phrased as "larger amount of LEDs". Size is not too important as an array containing ~10 strings would not take up much relative space in the aspect of what I am trying to accomplish. As far as potentially working with the 12V 2AH battery, I haven't done much research on those specifically but I am assuming that the Lithium type would provide the most optimal performance?

 

Lithium has the highest energy density, as far as I know, and easily beats lead-acid for recharge cycles, but
remember the variations on maximum voltage depending on the load? I'd have to know which variation of lithium you can buy to polish the numbers. Maybe even a high efficiency driver...

Pick a battery and we can run some numbers about the load current compared to the voltage sag. 60 is a lot more LEDs compared to 5 or 10. Then again, 12 volts will support longer strings, like about 7 or 8 per string.
7 x 8 strings = 56 LEDs.
8 times 7 strings is 56 LEDs.
8 strings is 0.4 amps, and presto, you have a 5 hour battery.
Do you NEED 56 LEDs worth of invisible light?
Try 5 or ten LEDs and you will soon know.

 

Lithium has the highest energy density, as far as I know, and easily beats lead-acid for recharge cycles, but
remember the variations on maximum voltage depending on the load? I'd have to know which variation of lithium you can buy to polish the numbers. Maybe even a high efficiency driver...

Pick a battery and we can run some numbers about the load current compared to the voltage sag. 60 is a lot more LEDs compared to 5 or 10. Then again, 12 volts will support longer strings, like about 7 or 8 per string.
7 x 8 strings = 56 LEDs.
8 times 7 strings is 56 LEDs.
8 strings is 0.4 amps, and presto, you have a 5 hour battery.
Do you NEED 56 LEDs worth of invisible light?
Try 5 or ten LEDs and you will soon know.

For the project I am attempting to complete, I will definitely need around 56-60 LEDs as 5-10 just isn't enough. As far as choosing a battery goes, most of the 12v batteries that I have found online tend to be in the larger range of size and I am hoping to have a portable device by the end of this process. I've found battery packs that are around 11.1V (http://www.batterysupports.com/108v-111v-3-18650-2200mah-3s-lithium-ion-liion-battery-pack-p-91.html) or (http://www.batterysupports.com/dewa...12v-lithiumion-repair-battery-pack-p-194.html) that I am assuming will work since they essentially achieve the same function. I wouldn't necessarily need to buy these pre-made battery packs if all they are is a series connection of 3 3.7V Li-ion batteries, as I could potentially make them myself.

Would something like these battery packs supply a sufficient amount of power for something similar to a 7 x 8 array?
I am also relatively inexperienced about mAh and how that will affect the circuit.

 

7 LEDs, 8 strings, .05 amps each = 0.4 amps.
9.45V at dead stop.
11.1V max expected. 33 ohms

I think they are both a stack of (3) round lithium batteries, just labeled differently.

Now, an amp flowing for an hour is an amp-hour. 0.4 amps is 400 milliamps.
400 milliamps flowing for an hour is 400 milliamp hours.
If you're going to run 8 strings of LEDs with a 1.5 AHr battery, it is supposed to last for 1.5 AHr/0.4A so hours =
3.75 hours.

a 2200 MaHr battery should last for 2200MaHr/400Ma =
5.5 hours.

You can run more or less strings of [7 LEDs and a resistor] to adjust brightness or hours per charge.

 

For the project I am attempting to complete, I will definitely need around 56-60 LEDs as 5-10 just isn't enough. As far as choosing a battery goes, most of the 12v batteries that I have found online tend to be in the larger range of size and I am hoping to have a portable device by the end of this process. I've found battery packs that are around 11.1V (http://www.batterysupports.com/108v-111v-3-18650-2200mah-3s-lithium-ion-liion-battery-pack-p-91.html) or (http://www.batterysupports.com/dewa...12v-lithiumion-repair-battery-pack-p-194.html) that I am assuming will work since they essentially achieve the same function. I wouldn't necessarily need to buy these pre-made battery packs if all they are is a series connection of 3 3.7V Li-ion batteries, as I could potentially make them myself.

Would something like these battery packs supply a sufficient amount of power for something similar to a 7 x 8 array?
I am also relatively inexperienced about mAh and how that will affect the circuit.

Can you give us a hint on the application: night vision/night photography, communication, ...
Maybe there are other ideas that allow reduced intensity.

Cheers

 

7 LEDs, 8 strings, .05 amps each = 0.4 amps.
9.45V at dead stop.
11.1V max expected. 33 ohms

I think they are both a stack of (3) round lithium batteries, just labeled differently.

Now, an amp flowing for an hour is an amp-hour. 0.4 amps is 400 milliamps.
400 milliamps flowing for an hour is 400 milliamp hours.
If you're going to run 8 strings of LEDs with a 1.5 AHr battery, it is supposed to last for 1.5 AHr/0.4A so hours =
3.75 hours.

a 2200 MaHr battery should last for 2200MaHr/400Ma =
5.5 hours.

You can run more or less strings of [7 LEDs and a resistor] to adjust brightness or hours per charge.

Thank you very much, It seems that this solves the last of my questions....for now. If I run into any specific problems during the physical construction of this array, I'll be back to these forums!