Comparing two 2400mah drivers, which one best?

TSellers · May 31, 2013, 12:47am

I’ve noticed a driver I had previously overlooked on Fasttech’s site, 1* Lithium 5-Mode 2.4A LED Flashlight Driver. It would seem to be similar to the Nanjg 7*7135 driver, but without the ability to select a mode.

As it appears to just have one integrated regulator, I was wondering if there would be any advantage to it over the Nanjg? Not being a fan of the SOS mode there would have to be some clear cut advantage to using it such as greater efficiency perhaps?

Slim_Pickens · May 31, 2013, 1:01am

In short you’ll probably best served by the 7*AMC7135 driver.

The Nanjg uses linear regulators for (surprise) regulated output :party:
Whereas the other driver will not regulate output.

TSellers · May 31, 2013, 1:26am

Thanks for that. So if it’s not regulated, would it be direct drive then?

Slim_Pickens · May 31, 2013, 2:24am

Yes, it would exhibit direct-drive-like decaying output.

ohaya · May 31, 2013, 2:39am

Hi,

Sorry to drop in, but I was wondering: If this is a direct drive driver, why would it be limited to 2.4 amps? Shouldn’t the output be dependent on the current that the battery is able to supply?

Slim_Pickens · May 31, 2013, 2:55am

You make a great point, and yes, if it was truly ‘direct drive’ the current delivered to the emitter could be disastrously high (thermal runaway—>poof). Since the input voltage directly influences emitter current I describe these types of drivers (FET, PWM’d modes) as direct-drive-like.

TSellers · May 31, 2013, 2:55am

I’m also trying to get my head around the direct drive algorithm.

ohaya · May 31, 2013, 2:58am

Ok, thanks. I had noted the “-like” in your post, but wasn’t quite sure how to ask if you were differentiating between “direct drive” and “direct-drive-like”.

So, if I’m understanding, the way that this driver would be characterized is:

- Output current to emitter decreases as input voltage decreases, and

Output current is limited to 2.4 amps

or something like that?

PilotPTK · May 31, 2013, 3:12am

ohaya:

Slim Pickens:

ohaya:

Slim Pickens:

Yes, it would exhibit direct-drive-like decaying output.

Hi,

Sorry to drop in, but I was wondering: If this is a direct drive driver, why would it be limited to 2.4 amps? Shouldn’t the output be dependent on the current that the battery is able to supply?

You make a great point, and yes, if it were truly ‘direct drive’ the current delivered to the emitter could be disastrously high (thermal runaway—>poof). Since the input voltage directly influences emitter current I describe these types of drivers (FET, PWM’d modes) as direct-drive-like.

Ok, thanks. I had noted the “-like” in your post, but wasn’t quite sure how to ask if you were differentiating between “direct drive” and “direct-drive-like”.

So, if I’m understanding, the way that this driver would be characterized is:

- Output current to emitter decreases as input voltage decreases, and

Output current is limited to 2.4 amps

or something like that?

That driver has no current limit. It’s about as direct drive as you get. The only thing that will limit current is battery voltage, spring/wire resistance and the RDSon of the mosfet.

PPtk

Slim_Pickens · May 31, 2013, 3:27am

Indubitably

If their specs are to be trusted it will be in the neighborhood of 2.4A. FT is traditionally better at actually testing their drivers than other budget vendors, but they’re still not infallible.
Edit: Exactly what PPTk said. Current draw from a fresh cell will vary between hosts, so YMWV.

Yes a healthy dose of ambiguity xD