Help, Weapon light is deforming batteries on MP5

My boss asked if the Surefire weapons light on his suppressed MPF could be hopped up a bit. It looks like an old round body 6P with a pressure switch tailcap and a shock bezel and is mounted with a single Weaver 1" scope mount.

I took it apart and it had a P60 in it. I noticed that the CR123 batteries in it were deformed. The sides had little ridges and valleys on them. Chris said all of their MP5s do that to the batteries.

I was curious if the shock bezel is allowing the light module to move around and then slam in to the batteries during the recoil from the full auto action. Can anyone confirm that this happens? Or is something else going on that I'm not seeing?

I gave him a Dereelight LED drop-in and a 6P bezel to test. I assume the LED module would not need the shock bezel. If my assumptions are correct, that will also stop the batteries from being deformed.

Any thoughts about this guys? I am hoping I am right because that may make a good argument in favor of upgrading their lights to LEDs. The deformed batteries would make me a bit nervous. It is doubtful that the person that makes the final decisions will care about making the lights brighter so we need another angle.

eep. the batteries are going to slam into that module. I'm not sure how well those fare.

as for little ridges and valleys on CR123As??!!!!!!
they're being crushed??!!

I don't know much about it, but I believe SF sells special batteries for their weapon lights. They look like 2 or more CR123a batteries shrink wrapped together.

The recoil of the weapon, not the lamp module is causing the cells to deform. You need to use Surefire SF223AC battery stick, which is essentially two 123 cells in a plastic tube with a felt washer between the cells.

Here's the sticking point: the SF223AC, due to Federal mandate can't be shipped, so you have to find them locally. They are still being made, as I use them (via Department) in my issued AR.

Or, you can replace damaged cells as needed, as they cost a lot less than the "early" days of lithium powered lights.

Dano is right - those issued WeaponLights as Police/Law Enforcement Officers should be able to source SF223AC battery sticks through official channels.

However, I find it strange that an 'regular' 6P is being used on a weapon rather than a for example model 696 for the likes of the HK MP5-SD. Are you sure it doesn't have a forward Lamp Module (called L60) and a central Universal Housing Body (called A21) onto which the remote tape switch TailCap screws?

In this photo the top model is 950-00, and the bottom model is 650-00

Thanks for all of the replies guys. I won't get another look at the light for a couple of weeks due to our training schedules.

I'm sure the light had a P60 and Z32 shock bezel. I suppose I could have been wrong about the body. It had the scope mount on it which could have covered the junction between the body and extension if there was one. It is a 2 cell light. The tailcap had the same markings as an old 6Z light I had and it had a larger hole in it than the current tailcaps just like the 6Z with the large button.

I wasn't aware that they still made the shrink wrapped 2 battery pack. I understand that it is the guns recoil that is causing the damage but I thought the shock bezel would allow more movement between the P60 and the batteries. By design, the light module has to move inside the shock bezel. In other words, I susppected that during multiple back and forth movements of the light during a full auto string of fire might cause the light module and the batteries to actually bounce off of each other slightly. I guess that question will be answered after Chris uses my LED module and standard 6P bezel.

An SF223AC stick isn't going to fix the problem completely. It will help prevent top button deformation for the bottom cell. But the top cell is still vulnerable. From the description, it sounds like you are using standard handheld bodies in a weaponlight application. Although a 9mm MP5 has fairly light recoil, it is possible that repeated shifting forward of the batteries is causing a problem.

Swapping the Z32 for a Z44 might help by reducing overall system compliance. But if there are springs involved (which at a minimum there is one at the tailcap), then there is still some compliance and the batteries can still shift fore and aft from recoil. If the batteries can move, then they can get battered.

In an handheld 6P body, there is no battery retaining rim at the top of body tube. A weaponlight body tube has a rim machined into it to hold the batteries back. This is easily demonstrated. Take a standard 6P. Remove the bezel. Turn the light upside down. The batteries will slide out and fall on the floor. This won't happen with a weaponlight body.

Is the MP5 an integrally suppressed model or using an external can? If it is the latter, if you get a dedicated MP5 weaponlight fore-end, you also need an offset adapter to clear the suppressor.

The MP5 has the built in suppressor. You would not believe how it is mounted. There is a small rail mount that is held on with a standard, $0.99 hose clamp! :sick2:

I'll check out the body as soon as I can. I'm not positive but I think there might have been a battery retaining rim in the body. I'm sorry I didn't pay attention to all of the details of the light.

The SureFire M23 mount is just a big ring that fits over the SD's suppressor, with a smaller 1" ring to hold the light.

SureFire WeaponLights such as the model 696 that should be used for mounting on an MP5SD have features specifically designed to protect the batteries and Lamp Assemblies from the effects of weapons recoil.

If you can remove the batteries from the bezel-end of the body then it is not a WeaponLight (the M600 ScoutLight being the exception).

SureFire WeaponLight shock isolation operates on a system of suspension with critically the baffle at the neck of the body.
(the baffle is actually in the Lamp Module adapter collar or Lamp Module Housing Body by the principle is that you can't remove the batteries by removing the bezel and Lamp Assembly)

The Lamp Assembly is suspended between the Neoprene gasket in the Shock Isolated Bezel and by it's -ve spring contact.
The batteries are suspended between the TailCap's spring contact and the Lamp Assembly's +ve spring contact. The theory being that both the Lamp Assembly and batteries are isolated from the body and bezel by these shock-absorbers.
To prevent excessive internal movement of the batteries the WeaponLight features this baffle that retains the batteries in the body and prevents them from slamming forward into the back of the Lamp Assembly. This results in a better protected Lamp Assembly, and helps to reduce the space in the body for the batteries to slam together resulting in crushed contacts etc.

Without the baffle of a WeaponLight the suspension system promotes movement and exposes the batteries and Lamp Assembly to being impacted by each other.

Does this make sense?

flip said:

The MP5 has the built in suppressor. You would not believe how it is mounted. There is a small rail mount that is held on with a standard, $0.99 hose clamp! :sick2:

Click to expand...

If this department has handheld SF's jerry rigged to their weapons, they could be risking battery fires or explosions.

SureFire offers a dedicated MP5SD Suppressor mount - M23 which is what the model 696 comes with...

SureFire also offers a Universal Mount - M13 for mounting to suppressors
or tubes having a diameter between 0.7 and 1.7 inches. Uses adjustable
(black oxide coated) hose clamps. Larger clamps are also available.

The M13 is included in the Model 669 weaponlight for the MP5SD.

I don't know what SureFire offers to options for the MP5SD
Model 669 using the M13 universal mount
Model 696 using the M23 dedicated (1.6" diameter) mount

My guess is that SureFire started with the hose-clamp mount and then introduced the dedicated mounts as the MP5SD became more widely used.

I haven't seen this problem in newer (past couple years) Surefire 123 batteries. I seem to remember SF saying that they were improved and that the 223A sticks were no longer necessary? Regardless, I have had no issues with new SF batteries in my duty and personal 870's which see plenty of use. I actually sectioned some battery tops and noticed the newer ones had slightly thicker sidewalls on the top contact button vs. a crushed older non SF battery I had.

Check that the springs aren't crushed, then use some new SF batteries. Also, maybe rotate between training and duty batteries. Or take out the batteries when doing lots of daytime shooting. Nothing is perfect and you want every advantage when playing for keeps!

Good Luck,

Dennis.

It does seem surprising that the MP5SD recoil has caused battery terminal damage. The integral suppressor ports bleed off enough bullet velocity to drop a supersonic round to subsonic in an already soft-shooting SMG.

It could be that the firearm is heavily used but the batteries are seldom changed.

I recommend changing out batteries for every scenario. Easiest and Surefire way of having everything working. That is of course a stop gap measure. Best to invest in a new weaonlight system and keep the old setup as a collectible.

I may be catching this thread towards the tail end but I would say if your batteries are deforming the way you described, from a suppressed fire MP5, they must have been in that thing for a long time or the gun must seriously cycle through some major rounds. This is not a fix but a mere suggestion. Change those bad boys out frequently. If not to avoid a battery leak or serious fire...causing major $$$ damage. It is an officer safety issue. Batteries are not that expensive. Having to go through a door during a high risk warrant with batteries that are about to take a poop on you is much more costly! I switch out my batteries on both my weapon mounted lights and my optics about every 3-4 months. Regardless of whether they are showing signs of use or not. Its a very cheap solution preventing a really big catastrophe! By the way...the SD model is SO MUCH FUN TO SHOOT! We switched ours out for the H&K UMP's. Still fun but not the SD! Good luck!