SF L1 question.

[Phil_B]

I want to use a rechargeable cell in my L1 while on holiday (I can recharge it from my motorbike), it'll mean lights on in the tent will be more guilt free. I have a lantern attachment for it.

The cell is a protected AW cell but it's 3.7V.

Is this too much for a stock L1 circuit?

I've looked and looked but can't find the information anywhere.
Thanks in anticipation, Phil.

 

[jugg2]

I wouldn't. I have an L1 and was told that the higher voltage will fry the circuit if you let it run for any amount of time. It will light up really bright, but i love my L1 too much to risk frying it haha.

 

[Phil_B]

I wouldn't. I have an L1 and was told that the higher voltage will fry the circuit if you let it run for any amount of time. It will light up really bright, but i love my L1 too much to risk frying it haha.

I love mine too, hence the question. Is your response definitive or hearsay mate? Where did you get your info if you don't mind me asking?
Phil

 

[foxtrot824]

I think this is a tricky one.

I had an L1 that was my EDC for some time and towards the end of it's career I started running IMR 16430 and enjoyed the output greatly. It did get warm quick so if you were using it as a tent light you might consider running it on low.

And most importantly this is at you own risk! Some L1s may deal with the higher battery voltage than others. I was ready to open mine up when I started running IMRs so I was ready to do an emitter swap if it fried. Again this is at your own risk!

 

[vtunderground]

The L1 has a boost driver, to power the LED (which has a vF of 3.2v or so) from a 3.0v battery. If you put in a Li-Ion battery, the boost driver sees a voltage greater than the vF of the LED, and switches to direct-drive. All of the sudden the LED is being fed up to 4.2v - a lot more than it wants!

Unless your L1 has an LED with unusually high vF, using a Li-Ion battery will cause the LED to run brighter, but with a greatly decreased lifespan.

 

[openbolt1]

You know I've been using an RCR123 since I bought my L1 with no problems whatsoever. I'll put a digital multi-meter on the contacts as soon as I have time. But as I recall the readings were normal.

 

[coloradogps]

You will fry it....

:thumbsdow

 

[foxtrot824]

As expected this thread will receive a variety of responses.

In my non professional opinion the Cree XR-E is like the chevy 350 of LEDs. It is a strong good building block, some what primitive and can be pushed beyond stock limits with shortened life span. If you look up specs on a Cree XR-E Q5 or Cree 7090 you'll find that the Vf at 350mA is 3.3 to 3.9. I believe that L1 current is closer to 700mA, most likely increasing the Vf to over 4 volts. Again reducing over all life span, however if the life span drops from 40,000 hours to 15,000 hours until 70% output for a flashlight that would still be a great life. I say go for it as long as you are ready to buy a new L1 if this one doesn't do so well with the increased voltage. :laughing:

 

[Bullzeyebill]

I would check the current at the tailcap area with a DMM using a fresh CR123, and note the current reading, then use an RCR, 3.7-4.2v, and note the current. If the current is appreciably higher with the RCR123, I would not continue using it with that cell. You may luck out and find you have a high vf LED, and if the current to the LED with the CR123 is close to 1 amp, which I am sure that it is not, then voltage sag can come into play and make use of an RCR123 safer. My recent personal experience using an RCR123 with a CR123 light is using an RCR123 in my SF T1A. I did the current check and found no significant increase in current draw on high, so I feel safe using this configuration.

Bill

 

[WadeF]

Here's my thinking. My L1 in stock form with a CR123 wasn't all that impressive with it's slight greenish tint, and 65 lumens or whatever it was rated for (I think mine maybe more in the 80-100 range). I have a lot of lights that would blow it away as far as output, tint, etc. However, the L1's build, UI, and efficient optic make it a really cool beast. So I still love it. However, I decided I'd love it more using a 3.7 lithium-ion in it to boost the output. I haven't had any problems yet, but I don't run it on high for extended periods of time.

My thinking is if I burn it up I will just send it to Milky for modification and make it way better than it is now. I don't see it burning up any time soon, if ever while I have it, but if it ever would there would be better LED options available to give it an upgrade, although I'd have to foot the bill for the upgrade. I would never send something back for a warranty repair if I used it improperly.

 

[MarNav1]

3v RCRs work just peachy. Most 3.7 don't fit anyway so no biggie.

 

[Phil_B]

Thanks for all your informative responses folks.

I had no idea the L1 went direct drive over 3V. Intyeresting.

I should mention that the light runs a XRG-R4 from a stock driver.
I have no idea on bin or Vf though.

I really don't want to mess this wee fella up as it's my (current!) favourite light.

I made a dum head from an old KX2 head, put tritium vials behind the optic and installed the emitter, and put "Oregon Shooters" tailcap guard on it. I love it!!

Think an XRG-R4 is man enough for 3.7V?

 

[foxtrot824]

XP-Gs are a whole different kind of beast. They have a lower Vf than the XR-Es, I think I would stay away from using and 3.7v batteries given that the emitter has been swapped. That's just my 2 cents.

 

[Bullzeyebill]

Yes, don't overdrive it with an RCR123. XPG will not like that.

Bill

 

[Phil_B]

Thanks chaps.
I've been looking for a protected 3v rechargeable cell and can't locate any.
Is there a brand out there?
I'm really keen to use a rechargeable set up on the bike holiday with this torch.
Can you help one more time?
Thanks, Phil.

 

[maxspeeds]

I only use rechargeables in my L1's. This is how they have been used for over 2 years. I have two, a 2nd generation and a 5th generation L1. I use AW black and red 3.7V li-ion cells everyday. I don't see any reason not to use them.

 

[Bullzeyebill]

The modification of the L1 to use an XPG LED makes a lot of difference compared to the original SF LED, of unknown vf. I would not just go ahead and an use it, unless I tested the current draw from an RCR123 for a short burst or so.

When Gene Malkoff started using the XPF with the M60 circuit he was burning out the circuits due to the low vf of the XPG, and he had to design another circuit to handle it. This I mention as an example of how different the XPG LED is.

Bill