Surefire A2 dimming LED???

senna94

senna94

Flashlight Enthusiast
Joined
Dec 9, 2005
Messages
1,750
Location
Houston, Texas
I have a new Surefire A2 with red led s that is still on its first set of batteries.
While I was using it tonight I noticed that the led s got noticeably dimmer. However, when I kicked on the incandescent lamp it fired right up on full brightness. I know that the led s are not regulated ,however I thought it strange that even after they dimmed the batteries have enough juice to keep the incan. regulated. Have most of you that own an A2 had this same experience? I havent put in a new set of batteries to see if the leds regain their brightness but I assume they will. I have cleaned and made sure that the dirty threads issue everyone has mentioned is not the problem. I would appreciate any feedback.

Paul

:shrug:
 
Last edited:
Krit

Krit

Enlightened
Joined
Dec 4, 2003
Messages
751
Location
Thailand
I use my A2 with recharge li-ion battery with no problem. A2 is very good for multipropose light.
 
switchoff

switchoff

Newly Enlightened
Joined
Dec 31, 2005
Messages
50
Location
BC, Canada
Krit said:
I use my A2 with recharge li-ion battery with no problem. A2 is very good for multipropose light.

What size li-ion batts are you using?
 
Krit

Krit

Enlightened
Joined
Dec 4, 2003
Messages
751
Location
Thailand
R123a 3.7 V lithium battery, same size as original 123a battery. It's rather tight to A2 battery tube, I use sand-paper to enlarge the hole tube. SF said in mail that the circuit can safety use with 2*123a li-ion battery and it also a little bit order drive to LED. I replace to NichiaCS Led and found that it's very bright for walk.
 
js

js

Flashlight Enthusiast
Joined
Aug 2, 2003
Messages
5,793
Location
Upstate New York
senna94,

This doesn't sound right. If the batteries have enough juice left in them to power the incan, then the red LED's shouldn't have dimmed at all--not even close. They draw so little power, and the CR123A's have such a flat discharge curve at those draw rates, that you wouldn't EVER expect to see noticeable dimming until they were almost dead.

And, yes, the LED's are direct drive, unregulated. But you will notice that if you remove the incan lamp, that they go brighter when the tailcap is pushed in to the incan-on position. This is because the 10 ohm resistor in the tail-cap gets taken out of the direct drive circuit loop.

It is possible that you had some funky or flaky 123's which at one point couldn't power the incan, but with the TC pushed in this far the 10 ohm resistor was out of play, then later, you back off a notch and noticed that, WOW, those LED's got dimmer. Then the batteries un-flaked, and you pushed again and noticed that they still powered the incan.

Try a new set of batteries and see what happens. If something weird is still going on, it points to contact resistance in the tail-cap or a problem with your LVR (regulator) circuitry--which is very, very unlikely.
 
senna94

senna94

Flashlight Enthusiast
Joined
Dec 9, 2005
Messages
1,750
Location
Houston, Texas
Thanks JS for all the great info. I will try new batteries and see what happens.

Paul

:wave:
 
leukos

leukos

Flashlight Enthusiast
Joined
Apr 8, 2004
Messages
3,467
Location
Chicagoland
What JS said. Batteries often have more technical difficulties than the A2. :)
 
Radio

Radio

Modulated Moderator
Joined
Oct 28, 2005
Messages
2,220
Location
The Land of Baked Beans and Red Sox
I am far from an expert but I do remeber reading that a member here had to replace the LED's in his A2 after running RCR123's in it as it damaged them. Seems some people run the A2 on RCR123 no problem and others have problems with the LED's. Just an FYI. BTW an A2 is on my "TO buy" LIST
 
leukos

leukos

Flashlight Enthusiast
Joined
Apr 8, 2004
Messages
3,467
Location
Chicagoland
Krit said:
SF said in mail that the circuit can safety use with 2*123a li-ion battery and it also a little bit order drive to LED.

Krit,
So you emailed SF about using Li-ions in the A2 and this was their response? :wow:
 
O

oldgrandpajack

Enlightened
Joined
Mar 15, 2003
Messages
931
leukos said:
Krit,
So you emailed SF about using Li-ions in the A2 and this was their response? :wow:




Personally, I would want that in writing, before thinking I am covered by the warranty.

Never have seen Surefire approve of rechargeable batteries, in anything other than their rechargeable flashlights, and then only when using Surefire rechargeble batteries.

oldgrandpajack
 
Krit

Krit

Enlightened
Joined
Dec 4, 2003
Messages
751
Location
Thailand
My friend ask to SF about how to use R123a and SF said A2 circuit can accept R123a for incan bulb. But LED will be over drive. I think if we change somethings to the stock design we should accept what happen. I use R123a for a long with no problem to incan bulb but led will more bright with over driven action. How ever I think that if led dramage I can change them easily. Some one chanhe to MJ LED which can accept more current without problem. My A2 change led to nichia CS U bin which brighter than stock led bulb when I use both 123a and r123a and I know that it's not cover the warranty.

I turn on LED mode for 15 minutes and no problem with my A2. BE Use on your own risk.
 

Similar threads

Brasso
Replies
0
Views
522
Brasso
Brasso
B
Replies
11
Views
3K
scout24
scout24
J
Replies
10
Views
3K
jso902
J
M
Replies
9
Views
2K
roberttheiii
roberttheiii
P
Replies
0
Views
607
Papacosmos
P
Top