LD10 driver details?

[BruceWillEs]

Does anybody know details of the LD10 driver circuit? I know that it's a boost converter, but i'd like to know far more, to understand the driver behaviour when being used with different cells (NIMHs, Lithiums etc...). For example, i want to understand, why the LED isn't destroyed immediately when driven with a fully charged lithium cell (3,9V). A circuit diagram would be nice!

Thx.

By the way: I am knew here hello i'm from germany, and i am starting to become a flashlight fanatic

 

[BruceWillEs]

Must knot be exactly the LD10. I think Fenix uses same or very similar circuits for all their lamps...

 

[Wiggle]

For example, i want to understand, why the LED isn't destroyed immediately when driven with a fully charged lithium cell (3,9V). A circuit diagram would be nice!

Full charged lithium is more like 4.2V. But at that voltage the driver is bypassed and that voltage drives the LED directly. 4.2V on an XR-E or XP-G can range from "driven pretty hard" to "overdriven". The light will heat up more than normal til the voltage sags into the range covered by the driver.

 

[BruceWillEs]

Full charged lithium is more like 4.2V. But at that voltage the driver is bypassed and that voltage drives the LED directly. 4.2V on an XR-E or XP-G can range from "driven pretty hard" to "overdriven". The light will heat up more than normal til the voltage sags into the range covered by the driver.

- Do you have a circuit diagram, where i can see and understand the bypassing function?

- I don't think that you are right with what you say about 4.2V. 4.2V are NOT anywhere between "driven pretty hard" to "overdriven", it is definitely overdriven. Please compare with the Cree Datasheet. 3,5V = 1500 mA, and when interpolating the curve, 4,2V must be somewhere at 10A, and this is obviously definitely too much. So, as i said, i think you are not right with what you said. But on the other hand i KNOW, that many people can drive their LD10 with Lithiums without the LED taking damage. So i think to understand this, we need a circuit diagram. Perhaps there is a common silicium diode in series to the LED, as this is quite common for boost regulators? This silicium diode would take a voltage drop of about 0,6 Volt, that would explain all.

 

[Wiggle]

Remember too that a typical Li-ion will suffer some voltage sag under that load. You're right, an ideal 4.2V source would be overdriven but with voltage sag it would be lower. As well, as the battery depletes, the voltage decreases as well.

I don't don't if you'll have much luck finding a circuit diagram, I can't imagine Fenix wanting to release that information. If there was indeed another diode in series with the LED that would certainly drop the LED voltage a bit, but would also waste a bit of energy.

 

[BruceWillEs]

Remember too that a typical Li-ion will suffer some voltage sag under that load. You're right, an ideal 4.2V source would be overdriven but with voltage sag it would be lower. As well, as the battery depletes, the voltage decreases as well.

I don't don't if you'll have much luck finding a circuit diagram, I can't imagine Fenix wanting to release that information. If there was indeed another diode in series with the LED that would certainly drop the LED voltage a bit, but would also waste a bit of energy.

Yes, you are right, a fully charged lithium has under load not 4.2V, but app. 3.9V. Do you agree? These 3.9V are still definitely too much for a XP-G, according to the Datasheet. (Maximum is 3,5V = 1,5A)

But why aren't all those LD10s destroyed, when beeing driven by that voltage? Their must be still some regulation, diode, resistor or anything else. I'd like to understand that.

 

[Ragiska]

lot more voltage sag than that. under even mild loads they only do ~3.7v (hence the rating). 3.2-3.5v under load would be what I'd expect for a fully charged cell.

also, keep in mind most accounts of l1d's and ld10's on a 14500 were for xr-e's, not xp-g's

 

[BruceWillEs]

3.2-3.5v under load would be what I'd expect for a fully charged cell.

Sorry, i don't think you are right.

http://eemb.com/pdf/Li-ion/LIR14500 (750mAh).pdf

According to this datasheet of a 14500 lithium cell, even under load (for example 1C) the voltage of a fully charged cell is somewhere in the area about 4V or even more.

also, keep in mind most accounts of l1d's and ld10's on a 14500 were for xr-e's, not xp-g's

Hm i dont get this point exactly, due to my bad english. I don't get it what "account" means in this context. Do i understand you right, that you want to say, that it is more safe to use XR-Es than XP-Gs when driven directly by a lithium cell?? (Damn, i own a LD10 XP-G R4, but want to use it safe with lithiums!)

 

[Ragiska]

Sorry, i don't think you are right.

http://eemb.com/pdf/Li-ion/LIR14500%20%28750mAh%29.pdf

According to this datasheet of a 14500 lithium cell, even under load (for example 1C) the voltage of a fully charged cell is somewhere in the area about 4V or even more.



Hm i dont get this point exactly, due to my bad english. I don't get it what "account" means in this context. Do i understand you right, that you want to say, that it is more safe to use XR-Es than XP-Gs when driven directly by a lithium cell?? (Damn, i own a LD10 XP-G R4, but want to use it safe with lithiums!)

look at the cpf li-ion shootout thread, on high is MORE than 1C, but is actually ~2C, and, and battery sag to <=3.5v nominal is common.

and yes, the xr-e has a higher vf than the xp-g.

but in short, if you wanted to run a single li-ion in a 1xaa size light, the ld10 was a bad choice. you should have gone with the quark aa, which has a boost/buck circuit, and retains all modes on li-ion.

 

[BruceWillEs]

look at the cpf li-ion shootout thread, on high is MORE than 1C, but is actually ~2C, and, and battery sag to <=3.5v nominal is common.

and yes, the xr-e has a higher vf than the xp-g.

but in short, if you wanted to run a single li-ion in a 1xaa size light, the ld10 was a bad choice. you should have gone with the quark aa, which has a boost/buck circuit, and retains all modes on li-ion.

Since i only use the turbo mode, it is no problem for me if the lower modes get lost. But will my LD10 XP-G R4 be destroyed when using 14500s? If yes: WHY?!? (As you demanded, i went to the Li-Ion Shootout Thread. There i saw again: You are wrong, with your opinion that fully charged Lithiums drop to 3.2V-3.5V under a load of 2C. This is not correct, my friend.)

 

[Ragiska]

Since i only use the turbo mode, it is no problem for me if the lower modes get lost. But will my LD10 XP-G R4 be destroyed when using 14500s? If yes: WHY?!? (As you demanded, i went to the Li-Ion Shootout Thread. There i saw again: You are wrong, with your opinion that fully charged Lithiums drop to 3.2V-3.5V under a load of 2C. This is not correct, my friend.)

at ONLY 1.5-2C

i don't think you understand how a li-ion cell behaves under load. in direct drive, the cell is under MUCH more than 2C load, but the voltage sags much lower at the start. these graphs were created under constant load, which is not entirely comparable.

and when you first turn the light on (in direct drive) and it tries to draw even more current, what do you think happens to the voltage? it goes down, so it cannot sustain the current.