Surefire M2 Battery Drain?

Hi all,

I've had a Surefire M2 for a few years now. I use it for emergencies only. I've noticed lately that it needs a new set of batteries every few months. I usually put a new set in and keep it in the glove box of my car. When I came back to use it this week it needed a new set of batteries, again. What gives? Is the flashlight somehow draining batteries? I'm always careful to twist the tail cap more than a few full turns to prevent accidental power drain.

Other than that, Surefire, as always, has done a great job with this flashlight.

Hi Lumenous, before you come up with a conclusion that the M2 drains batteries while not being turned on, why not look at other factor? What about heat build up from the sun? Cold temperature? Expired batteries? All these are factors that causes your batteries to weaken.

Fellas,

There's over 1000 members on here and all I get is one response. M2 owners where are you?

I have an M2 that's about three and a half years old. I don't use it much, and don't remember when the last time I changed the batteries. At least 2 years ago though. It hangs from the bed post, and I checked it with the batteries in it and with some new batteries- no difference that I can tell.

I've got the original tail cap on this one. What are you using on yours?

I've been contemplating getting the click-on lockout tailcap.

If you have a voltmeter, check the voltage of the batteries once a week. If there's a slow and consistent loss that would narrow it down to either a short in the light or the environmental conditions in the car. Or try keeping the light in your house. If the same things happens you'll know it's the light.

If the voltage remains normal for a long time and then suddenly drops a lot, a battery has gone bad. There have been quite a few posts about sudden battery death with 123 cells, often involving Surefire batteries.

Lumenous, Mine has the original tail on it also. I'll probably keep it that way, since this light is for using along with a handgun the way it was designed. I've got other lights to use for regular duties.

Lumenous,

You'll be pleased to hear that I've had the exact same problem with my M2. I've also had it happen with one of the 2 G2's I own. I suspected battery problems but it has happend again since, this time after a couple of sets of batteries had been through since the last time.

On the G2 I eliminated the problem by unscrewing the bezel so that it couldn't be turned on by the tailcap.

As I don't own a multimeter I cant check to find some type of electrical leak which might explain this phenomenon.

Doug

I'm going to keep the batteries out of the flashlight. Since I only use it for emergencies it will also keep the light nice and clean and prevent wear and tear.

An emergency use light without batteries inside isn't rapidly deployable. If it was my light I'd determine the cause of battery failure, if for no other reason than to educate myself. I keep batteries in all 68 of my lights for the same reason I only use mechanical, not wood, pencils - half the time the lead is broken.

[ QUOTE ]
Lumenous said:
Fellas,

There's over 1000 members on here and all I get is one response. M2 owners where are you?

[/ QUOTE ]

/ubbthreads/images/graemlins/icon3.gif Don't know. I have several lights and until recently when I ran out of batteries had 123A's installed in all of them, some weren't used much but none of them were drained after leaving them alone for a long time. /ubbthreads/images/graemlins/icon3.gif

Jayflash,

That's a good point. How would you go about finding the short out in a flashlight? I must say the flashlight was never dropped or modified since I purchased it. It's been three years since I got it. If I remember correctly they come with a one year warranty?

Surefire come with lifetime warranty.

I have had allot of sudden death problems with surefire batteries.Not just in surefire lights.The last time it happened I check both cells and found one had gone bad.It would not even light up any of my led lights.If this happens to you again,check the voltage on both cells.

If your lock out tail cap is locked out there is no way your M2 can be draining the cells - unless the switch is, both, defective AND something is pressing on it. I don't have an M2 but am judging from how the E2 & G2 tail caps work.

As was mentioned, it could possibly be your cells. Some SF 123's will die in storage after heavy use, but well before they should have been used up. If all your cells were from the same batch, maybe it was a bad production run. Try some fresh cells of a different brand.

Could your glove compartment light remain on when the door is closed and the sun is heating up the dash board and interior? I always put a window sun shield in place if I park in the sun - especially if the window faces the sun in the spring, summer, and fall. It would take a lot of heat for extended periods to degrade a normal CR123 but if a vehicle is in the sun all day, every day, who knows? I'm running out of ideas.

Let us know if you find your problem so we can learn from your experience. Thanks, lumenous.

Something interesting happened today. I was testing the flashlight and left it on for a bout 10 minutes. The flashlight became very hot to the touch at which point it shut off. I turned it off and left it to cool for about 5 minutes. I then turned it on again and it worked fine. Then it got hot again and shut off. Any ideas?


The flashlight normally sits in the glove box. My car is parked in the garage for the majority of the day. I park it in a garage at work and at home. It's always protected from the elements. So the environmental effects on the batteries are very minimal.

Which lamp assembly do you have in it and what brand batteries?

I carry my M2 in my pocket all the time and I've never had battery drainage that seemed unusual. Ditto with my previous M2 before I lost it (doh!). Currently I am running the HOLA and SF batteries. This light see pretty light usage.

I don't recall ever seeing any closure on this, but quite some time back someone wondered about lithium battery life with no usage vs some usage. He suspected that if you didn't use the light you would get the full battery shelf life, but if you used it some you would start losing shelf life much more rapidly than we would have thought.

-john

John,

I'm using the P61 SF bulb along with SF batteries.

PS: Does your M2 get extremely hot to the touch after 10 minutes of it being on?

Sounds like you are triggering thermal shutdown in the batteries. The fact that you are using the P61 lamp could also explain why you're getting such lousy runtimes; its rated for 20 minutes per set of batteries.

And yes, my M2 with P61 gets very toasty after 10 minutes constant on.

Yesterday was the first time I had it constantly on for 10 minutes. When I put new batteries in the M2 I used it for less than a minute and then stored it in the glove box. Three months later when I came back to use it again it needed a new set. I'm going to look into trying a different batch of batteries.

Is thermal shutdown unavoidable? Is it a normal thing for a flashlight to do when used with high intensity bulbs?

Now that I know that with the P61 I can expect it to get a little toasty after 10 minutes I've replaced the P61 with a P60, it runs much cooler.