Surefire M4 Mod

[electrichead]

Hello all! I have a Surefire M4 with the Leef body that accepts 4 CR123's and SW02 tailcap. As of right now I am using CR123 cells in it. I am looking to replace my 9AN with the M4 for nightly police work.

It is my understanding that I have the ability to run 2 18650 batteries in the light body. Can anybody suggest the best batteries / charger for daily use? Also do I need to make any additional mods to the light to safely run rechargeable batteries (new bulb? tailcap?) I would prefer a quick car charger for the batteries, though it is not an absolute necessity. Are there any special considerations when it comes to rechargeables i.e. can I only charge once a day, etc. My plan is to purchase at least 2-3 sets of batteries so I will always have a set on standby. As previously stated this will be used a lot. To give you an idea I currently go through 2-3 batteries in my SF 9AN a night. I have limited knowledge of electronics, so if you could dumb down your answers for me it would be greatly appreciated!

Thanks- J

 

[Echo63]

The M4 is a 12v light, and it is a little tricky to find a 12v battery solution that fits without extenders or dummy cells.

the best option is running 2x 17670 or 18650 cells (you mention the leef body, so it may fit the fatter 18650 cells)
Most CPFers reccomend AW's lithium ion cells, either the protected (black label) or IMR (red label) depending on the current draw you plan on subjecting them too

you will need either a genuine M3T bulb from surefire, or one of Lumensfactory's M3T bulbs. these bulbs will blow if fed 12v from 4x 123 batteries though, so you will need to keep the current bulb with the spare 123s if you intend to use them in case of emergency.

I am currently running my M4 on primarys, with the stock globe
i intend to buy a lumensfactory HO-M3t soon, and run rechargeables in it.

one more option - Lumensfactory make a P7 LED head that will fit your M4, it is very bright, and will make your batteries last a little longer.
it also runs from around 7v to 13v - so it is fine with either 2x Lion, 3x Lion, and 3 or 4 Primary cells. it will if run on 4x rcr123 though

Im sure one of our other, more experienced members will be along in a tick, with some more info, but this should start you off

 

[Outdoors Fanatic]

I recommend getting 2x AW 2600mAh li-ion cells, a Lumens Factory HO-M3T or EO-M3T lamp assembly and this charger -->> http://store.bugoutgearusa.com/bach.html

 

[jaundice]

Sorry, I misread your first post, and basically wrote a bunch of stuff that doesn't apply in this situation.


-John

 

[Owen]

He has the Leef body, so it already takes 18mm cells.
The Lumens Factory HO-M3T, and Pila IBC charger are a good bet.
Probably a good idea to get the highest capacity unprotected cells you can find(I don't know what that is at the moment).

You'll need to remember to change them out and charge them when the light starts to dim, but it beats having protected cells suddenly cut off at the wrong time. Cells with a circuit to protect against overdischarge will abruptly shut off when the voltage drops below a certain point.

If it's going in a holster, need to ditch that SW02 for a Z41-HA or Z58. Those will give you easier access for momentary use, as well.

btw, if you are planning to use a holster, and use one for your 9AN, take off the SW02 and try the M4 in it. That turbohead may not be comfortable for you to wear on a duty belt, especially in a high ride rig with a closed bottom.

 

[jaundice]

Owen;

Good spot. I missed that the first time around! I've edited my post to remove my misunderstanding of the OP's situation.

I profoundly disagree with your suggestion to go for unprotected cells: The last thing the OP wants to do is worry about over-discharging his cells in a tight spot. Protected cells will let him know that he's almost out of juice by dimming before automatically shutting off. Besides, the highest capacity unprotected cells only run at 3000 mah, vs. 2600 mah for the protected AW 18650s.

-John

 

[Owen]

Well, maybe you'd rather lose a suspect, have your light go dead on a traffic stop, or get your *** shot than run a battery down a few tenths of a volt too much in a "tight spot", but you're welcome to disagree as profoundly as you want to:thumbsup:

 

[socom1970]

FWIW, I agree with Owen about using unprotected cells for exactly the reason talked about. I have had my protected AW's shut off on me many times.
I could not imagine the nightmare that would cause electrichead or any LEO if the cells shut off on him when he needed them the most to save/protect his life or his partner's life.


Bottom line is to use the unprotected AW 18650 cells. (Best ones out there) They will work just like regular batteries, just that he will have to swap them with fully charged ones when they start going dim. If he is in a bad situation when they are dimming, big deal. Better to slowly kill $14.00 worth of unprotected Li-Ion cells to give him valuable light than to protect the batteries by shutting themselves off and he's DEAD. Screw that. He can always buy more batteries... I would gladly burn up $14.00 worth of Li-Ions to save a life.


The Lumens Factory Seraph P7 head is something I really think you should consider getting. (http://www.lighthound.com/Lumens-Factory-P7-M-Head-Assembly_p_3248.html )
It is REALLY, REALLY bright, has a HUGE, long-throwing hot-spot with decent spill light.
IMHO, it kind of reminds me of the Surefire M6 500 lumen beam pattern. I'm talking scary bright with a HUGE column of light. See below:

ON LEFT = Surefire M6+MN21 at 500+lumens ON RIGHT = Surefire M4+Seraph P7 at approx. 950 lumens


As well, the Seraph P7 head is a smaller size than the M4 turbohead is. Much more convenient, especially if you will be wearing it on your duty belt. I use my Seraph P7 head with my bored out M4 and AW 18650's and it is my favorite combo for a full-size light. See below:

ON LEFT = M6 (KT4 head, same as the M4) ON RIGHT = Surefire M4+Seraph P7 head

Truly a formidable force-option.:thumbsup:

 

[Justin Case]

Li-ion protection circuits typically seem to have an overdischarge voltage cutoff around 2.7V. So I don't see how using unprotected cells helps in some theoretical situation where you need to run your light down as much as possible because of some exigent circumstances. In fact, some tests here show that usually the overdischarge protection never even kicks in.

 

[electrichead]

Thank you everyone for the excellent advice! I think I will be going with an unprotected 18650 setup, and just be cautious about changing out batteries. As it stands I carry more than one light while working, but I still don't like the idea of having a primary that will shut off without notice!
Thanks- J

 

[electrichead]

Socom1970 I really like that Seraph! What type of runtime can be expected with rechargables? I was looking to find a LED setup...

 

[jaundice]

Well, maybe you'd rather lose a suspect, have your light go dead on a traffic stop, or get your *** shot than run a battery down a few tenths of a volt too much in a "tight spot", but you're welcome to disagree as profoundly as you want to:thumbsup:

Getting shot is a bummer, but what would really keep me on edge is the fear of dinging that beautiful Leef Body!

Seriously, as the voltage drops in those cells, the light output is falling dramatically. I would argue that in any exigent circumstance, your duty light should be thrown on the ground and your pistol-mounted weaponlight used as your primary light. In the case of a foot pursuit of a misdemeanant or traffic stop a backup light would be more appropriate, but nonetheless, every officer needs to have a plan worked out on what happens when their light dies.

-John

 

[Echo63]

Socom1970 I really like that Seraph! What type of runtime can be expected with rechargables? I was looking to find a LED setup...

mine runs about 50 mins on 2x 17670
you will probably get an hour and 20 mins or so on 2600mah 18650

 

[socom1970]

Socom1970 I really like that Seraph! What type of runtime can be expected with rechargables? I was looking to find a LED setup...

I get about an hour on my AW 2200mAh 18650 Li-Ion cells. With the unprotected AW 18650 cells, you'll hopefully get about the same.

If you want to get really crazy, get one of the 3x18650 C to M Leef bodies (if you can find one). I thought I saw one on BST, but I can't find it at the moment. I really like mine a lot. I use it along with the Seraph when I go night-hiking or caving. Great runtime and nice balance for a large light.

Always have a backup light. I would highly suggest the SF E1B Backup or the E2D Defender. I know that is an obvious thing to say, but I would be wrong if I did not promote that ideology.

And whichever cells you use, test them every once in a while. And keep a couple sets of spares and swap them out when you think about it or feel like it. I do that on a regular basis, sometimes not testing them at all, just putting the old ones in the charger and full ones in the light.