Best way to drive R2 with 2x18650?

[A380]

Hi everybody.
I'm going to make a dual-bored 1D mag with a R2 and 2x18650 protected cells.
First I wanted to DD from 2p batteries, but I wonder if theres is a better way to drive it in terms of efficiency/runtime with a driver and/or putting the cells in series.
I asume that DD with 2p it will last about 2hous before dimming but I'm not shure.
Thanks,

Ot.

 

[Mirage_Man]

Depends how hard you want to drive it but a SOB converter from the Shoppe would work for your application. You will want to pot the driver though as there will be a decent amount of heat to dissipate.

 

[BurlyEd]

For $35 total cost you could buy a Solarforce 300 Lumens CREE R2 LED 5 Mode Flashlight:
http://www.solarforcestore.com/servlet/the-851/CREE-LED-R2M/Detail
Plus a Solarforce 18650 Extension Tube L2-E18G:
http://www.solarforcestore.com/servlet/the-906/EXTENSION/Detail

The $35 deal includes a good holster and a single unprotected 18650 battery.
That is not really a mod, but it is what I did (actually I bought the single mode version).
Note: these are 300 ebay lumens, not real lumens.

 

[A380]

Actually I don't mind driving it really hard. When the led goes "byebye" I'll replace it.
Efficiency with the Sob converter is 75-85%. For a 2s cell configuration maybe a buckpuck 95% efficiency?
On the other hand, if I go for a 2p configuration I could use a GD 1000 Buck/Boost Converter with 85-93% efficiency.
Don't know, I'm still very confused.

BurlyEd, It's true, there are some nice cheap lights out there, but I want a focusable light (going to use an aspheric lens).

 

[Justin Case]

If you use a driver that outputs 1000mA, you won't be overdriving the R2, so there is no issue there.

My experience with the SOB1000 has been that the efficiency is closer to 85%. Still a bit lower than the advertised efficiency for the Buckpuck, though. Also more expensive than the Buckpuck. The Buckpuck appears to have a relatively high input voltage headroom of at least 2V, although that should not have any effect on performance when using 2x18650 in series. Vbatt is nominally 7.4V, which is well above the ~5.5V needed for the Buckpuck to run in regulation. And your Vbatt should never go down to 5.5V anyway.

I've always used an SOB1000 when using 2xLi-ion because I need the 14mm round form factor for my driver. Works great.

I'm also using a GD1000 to drive a Cree 4P MC-E with 3xNiMH and the driver works very nicely. I get about 90% driver efficiency.

It can't hurt to pot a driver in general. But I don't think that you really need to do it. If we assume that the R2 Vf is ~3.5V at 1000mA forward current, then the SOB1000 has to generate about 4.1W at 85% efficiency. Thus, the SOB has to dissipate about 0.6W as heat. The GD1000 case should generate even less heat since its efficiency seems to be slightly higher than for the SOB.

 

[A380]

Thaks for the answer.
For now the firts option would be the buckpuck.
If I wanted to overdrive the led, which other options I have?

 

[bigchelis]

Thaks for the answer.
For now the firts option would be the buckpuck.
If I wanted to overdrive the led, which other options I have?

In an actual lumen test done by MrGman in his calibrated sphere..
Here are some XP-E R2 out the front lumens done...

1. The 1D Mag R2 at 1.4A did 170 out the front
2. The ID Mag R2 at 1A did 186 out the front
3. Using a P60 hosts and P60 design a R2 at 1.4A did over 200 out the front. P60 R2 was done by Krammer5150.

After testing the Mag R2 with those 2 current levels I would have said for sure 1A gives you more lumens, but after Krammer5150's P60 R2 made over 200 lumens I think their are others factors out there.

 

[bigchelis]

For $35 total cost you could buy a Solarforce 300 Lumens CREE R2 LED 5 Mode Flashlight:
http://www.solarforcestore.com/servlet/the-851/CREE-LED-R2M/Detail
Plus a Solarforce 18650 Extension Tube L2-E18G:
http://www.solarforcestore.com/servlet/the-906/EXTENSION/Detail

The $35 deal includes a good holster and a single unprotected 18650 battery.
That is not really a mod, but it is what I did (actually I bought the single mode version).
Note: these are 300 ebay lumens, not real lumens.

The Solarforce P60 R2 is an awesom pill it made 202 out the front lumens with 3 primaries in MrGmans sphere.:thumbsup: