The simple elegance of direct drive ;)

I just received my first direct drive module recently & have been marveling at what a wonderfully simple setup it is.

Just an emitter & single cell.
It's an XPG2 dedomed on copper with extra solder in the pill & I'm using a zero Rez twisty with raw Panny PFs.

I love how much output I have with no power wasted as heat from 7135s (just heat from the LED haha).
But the runtime is great and has a LOOONG taper before even approaching the 2.5V zone.
And it's PLENTY obvious when it's getting low.

I've been semi obsessed with max output & regulation in the past but for what I'm using this light for it's the perfect set up.
No danger with it not locking out & clicking on in my pack and single mode so the twisty isn't annoying.

It's not a light that I'd want to loan out unsupervised of course although if it did get left on & ruin the cell I'd just toss it since PFs are only ~9$ each.

Just thought Id share my observations & say that "flat regulation" isn't everything & isn't probably happening in hi amp single cell lights anyways.

Free yer mind & drive that sucker!

Cheers

Hope the MT-G2 modders are reading..

^^yah but MTG2 is a different story as they have a high VF of ~6+ volts so they need two cells.
But two IMR 18650s isn't going to sag much below 8v at start up, so yer going to get a HUGE rush of current and will need some serious heatsinking & direct bonding

The cool thing is it will also have a fairly long taper at the end & even with two cells it's going to be SUPER dim before damaging the cells!

In a P60 tho popping the MTG2 with too much voltage on two 18650 cells is common hence Vinh not selling them anymore.

psychbeat said:

I love how much output I have with no power wasted as heat from 7135s (just heat from the LED haha).

Click to expand...

If your battery voltage / internal resistance matches the LED well, the AMC 7135 will drop 120mV - assuming a LED VF of around 3V, that's about 4% of the total power dissipation.

There is no magic - something has to dissipate the excess voltage / power, either the battery (internal resistance) or the LED will be overdriven.

But the runtime is great and has a LOOONG taper before even approaching the 2.5V zone.

Click to expand...

The same thing will happen with the AMC7135.

If you were to add a few AMC7135s to your direct drive light, all that would happen is that the max current will be limited, everything else will stay pretty much the same.

Understood
But the 7135s would usually come on a driver board for me (since I don't make my own drops) and would flicker with low voltage warning etc & at higher currents it seems like the voltage drop is higher but maybe not.


My dmm leads are too thin & crummy to get a proper tailcap current reading.

It's just kind of neat knowing all of the cells energy is going straight to the emitter & not wasting any on heating up the driver
And filling that driver space with solders nice too haha

StarHalo said:

Hope the MT-G2 modders are reading..

Click to expand...

How about direct driving an MT-G2 with LiFePO4? Two cells would supply about 6.4V, which is just about perfect. Not sure if you would want to run it on three cells (9.6V). But with the innate regulation of LiFePO4 and the high current capabilities, such a light might work REALLY well.

http://i912.photobucket.com/albums/ac323/vinhnguyen54/9149490965_6361c26c64_o_zps4bf94f86.jpg



Idk - the VF looks a little high on this chart ...
Would be good for lower currents tho..

I did two simple MT-G2 swaps into Home Depot Defiant lights (a 3C super thrower and a 3D Armormax). Direct drive using 2S LiIons is a nice bit of cheap and instant gratification and these HD lights have a lot of metal for the heat, and being cheap lights they have enough resistance in the circuit path to buffer things. I'm thinking of doing some resistance mods and dropping down to LiFePo cells for the 3D unit.