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Star Bird
04-28-2014, 07:57 AM
The NB has 2 Amp output but also no real drive regulator?
If I have a battery that has 3400 mAh ,is the led getting just the 2 Amps or is it getting 3400mAh.?

Also same with batteries with lower current ratings . If a battery has only 1 1000mAh will the led get just 1 amp?

Forgetful Jedi Knight
04-28-2014, 08:15 AM
A 1000mAh will discharge a little over 1A, the 3400 can discharge around 3A. The NB typically "takes" up to a 2A draw from the battery and passes it on to the LEDs.

mAh, is a measurement of current over time milliAmphours. So in theory, if you have a 3400mAh battery, and are giving a LED 1A, the battery charge should last 3.4 hours.

Star Bird
04-28-2014, 08:47 AM
A 1000mAh will discharge a little over 1A, the 3400 can discharge around 3A. The NB typically "takes" up to a 2A draw from the battery and passes it on to the LEDs.

mAh, is a measurement of current over time milliAmphours. So in theory, if you have a 3400mAh battery, and are giving a LED 1A, the battery charge should last 3.4 hours.

...so if it typically takes 2 amps and gives it to the led. its going to give 2 amps to the led no matter how high the battery's mAh are?

if I have a 4000 mAh battery I would theoretically last 2 hours with the nano pushing out 2amps to the led?.... its not going to push out 4amps to the led for 1 hour right?

Silver Serpent
04-28-2014, 08:52 AM
That's correct, more or less. The LED will take the current it needs. If it only needs 1A, that's what it'll take. The Nano isn't "pushing" the current, more like allowing the LED to pull that much. Your 4000mAh example battery would last 4 hours if you were only drawing 1A.

A general rule of thumb is that your maximum safe discharge rate for a li-ion battery is roughly twice the capacity. A 4000mAh battery can typically support a 8000mA (8A) discharge without risking damage to the cell. The battery doesn't necessarily discharge at its maximum rate all the time, but it's good to know how high you can go safely.

Star Bird
04-28-2014, 09:21 AM
Ah but the nano will only allow up to 2 amps to be taken from the battery to the led even if the led wants or needs more than 2 amps?

Silver Serpent
04-28-2014, 09:45 AM
The NB won't prevent more than 2A from being taken. But it's my understanding that if you run more than that, you start running the risk of overheating and damaging the NB.

Forgetful Jedi Knight
04-28-2014, 09:57 AM
The NB won't prevent more than 2A from being taken. But it's my understanding that if you run more than that, you start running the risk of overheating and damaging the NB.

The "safety margin" is fairly substantial. ;)

Star Bird
04-28-2014, 10:25 AM
Well Im just wanting to know my options. Like I know some tri-rebels and tri-crees each dice can take up to 1amp so wired in parallel i would need 3 amps total. Same with a quad. that would be 4 amps total. How far is the safety margin willing to go ?

Also would my battery have to be the same or greater than the current required front the led right?

Forgetful Jedi Knight
04-28-2014, 10:41 AM
Let's back up a second, NB's are an "entry level" board. Originally, they were designed for a single LED in mind. Now, three die setups can be handled (2 main, 1 FoC) with an 18650, which is still very bright. This is not an "I can light up a small city" with this board.

I would strongly recommend that if you are going to use an NB, you stick to using three die setups. ;) Anything past that you risk damaging your board, and there is no guarantee that your battery will pump out that kind of current anyway. Also make sure you use the proper resistors.

Star Bird
04-28-2014, 10:53 AM
HAHAH! a small city that cracked my up .
but ok I won't go past a tri then. But would you say up to 3 amps going thorough the board is acceptable ?
I would think at least 2100millamps has got to be ok tho right?

Forgetful Jedi Knight
04-28-2014, 10:54 AM
HAHAH! a small city that cracked my up .
but ok I won't go past a tri then. But would you say up to 3 amps going thorough the board is acceptable ?
I would think at least 2100millamps has got to be ok tho right?

That would be fine, if you are doing 3 reds. Resistor properly.

Star Bird
04-28-2014, 11:00 AM
Thank you guys as I continue to feed upon your knowledge

Obi1
04-29-2014, 05:53 AM
I tried for one of my sabers to have a 3-Cree driven with an NB. My impression is that the NB will limit the overall current to 2A no matter how many dice you have in parallel. I had a potenti-o-meter :) regulating the series resistance to the dice, when I gradually opened up the 3 LED's, up to a given point the light intensity increased, but then I could not tweak out any more, so the board limited the current which could be sourced by it. It's of course an experimental result, without knowing the exact details how Erv designed NB's safety features.

DeadPuppy
04-29-2014, 03:08 PM
Thanks for all the info in this thread. This is something that has been confusing the heck out of me for a while.

I'd been reading that you could drive 1A to two dice on an LED...but that would already meet the max rating on the NB. I was wondering how in the world you could safely run 2A to the leds while still running the board and a 2W speaker without damaging the NB. It's good to know that there is a nice factor of safety...though it would be nice to know exactly what the limits are; The user manual just says 2A with the high power LED. I was considring resistoring all the dice to keep every led below 750mA to be safe. Resistors no more!..cept of course for reds & such.

Forgetful Jedi Knight
04-29-2014, 03:14 PM
Use this as a rule of thumb. You can use up to 2A for your main LEDs. Use external resistors, to prevent overheating the board, even for the higher voltage colors. Overheating the board causes un-triggered swings and such.

Star Bird
04-30-2014, 10:05 PM
I tried for one of my sabers to have a 3-Cree driven with an NB. My impression is that the NB will limit the overall current to 2A no matter how many dice you have in parallel. I had a potenti-o-meter :) regulating the series resistance to the dice, when I gradually opened up the 3 LED's, up to a given point the light intensity increased, but then I could not tweak out any more, so the board limited the current which could be sourced by it. It's of course an experimental result, without knowing the exact details how Erv designed NB's safety features.

So you are saying it will only give 2A no matter what. hmmm In that case I wonder if it be brighter to just have 2 dice each getting 1 amp rather than 3 getting 660ish mAhs each?

. But how was the 3-Cree's performance ? and what color? ( I just ordered a 3up blue )

Forgetful Jedi Knight
05-01-2014, 02:04 AM
For colors that could take 1A, you would be better off running 2 at 1A. I said you could do 3 reds, because they don't need that much. You could try the 2 reds at 700 mA, and see how you like it.

Obi1
05-01-2014, 01:09 PM
I quicky looked up the datasheet of a Cree-MC-E, which I built in into my latest addition. There is a chart showing the light intensity scaled to a nominal value (350mA for Cree HP-LEDs). On the chart it can be seen, that the intensity is close to a linear function of the current, slagging down at the last Quadrant only. I guess you have to have a closeer look at the datasheet of the LEDs you bought and make the maths, maybe you find an optimum using all the 3, but due to the linearity and the space the additional wiring of the 3rd LED takes up, the 2 blues each with 1A is probably the best you could do.

Star Bird
05-03-2014, 09:37 PM
For colors that could take 1A, you would be better off running 2 at 1A. I said you could do 3 reds, because they don't need that much. You could try the 2 reds at 700 mA, and see how you like it.

Could I do 3 cree blues in parallel? Or would it be bad for the board ?

Forgetful Jedi Knight
05-03-2014, 09:54 PM
Could I do 3 cree blues in parallel? Or would it be bad for the board ?

Running all three at the same time? Technically you could, but they wouldn't be very bright. Each would get less than 700 mA. You would be better off running 2 at 1A, it would probably be quite a bit brighter.

Star Bird
05-04-2014, 12:08 PM
9837 9838

Just thought Id try both and show the comparison. Left one is all 3 in parallel and the right is just two. Theres the proof 2 is better 3 with the nano :)

Forgetful Jedi Knight
05-04-2014, 01:05 PM
9837 9838

Just thought Id try both and show the comparison. Left one is all 3 in parallel and the right is just two. Theres the proof 2 is better 3 with the nano :)

Thank you, thank you... I'll be here all week. :D ;)

Obi1
05-07-2014, 01:41 PM
Wow, actually both are quite bright!!! That's a blade which should come with protective Googles...

I have to make by the way a correction to what I've written before. I was curious about the 2A Limitation we had been discussing, so I asked Erv as the only source of truth when it comes to his products. As Forgetful Jedi Knight mentioned absolutely correctly, 2A is not a limitation. Technically it's a so called absolute Maximum Ratings, which means if the user/application goes above this value, there is no garantee the device will work and damage might occur. But the current flowing will be determined by the load you apply, so you have to ensure no more than 2A through all your LEDs (despite of the substantial safety margin of the driver).
Of course with increasing current the voltage drop over the wiring will increase as well (wires can be considered resistors, U=I*R), reducing the voltage to the LEDs, which in turn reduces their intensity. It would be quite interesting to measure the voltage between the anode and cathode of the LEDs in the 2 and 3 LED setups of yours.

Forgetful Jedi Knight
05-07-2014, 01:46 PM
I was curious about the 2A Limitation we had been discussing, so I asked Erv as the only source of truth when it comes to his products.

Which is how I know what I know about his products as well. ;)

With the limited amount of wiring involved in a saber, the voltage drop is negligible because you're basically talking about less than 6 inches of wire involved in the circuit.

Martyn
09-06-2014, 12:12 AM
One thing to note for Tri Rebel setups with FoC. If you're using a Power Xtender for NB FoC (and you really must), while a small amount of board current is used via the FoC pad to activate the Power Xtender, the main drive current for the FoC is drawn directly from the battery, bypassing the board itself. Bear that in mind when making your calculations.