Upgrading a Surefire M6

[nightowl415]

I am new to the forum and in need of some advice.

I have been using a Surefire M6 for a few years and have finally run out of patience (and money) over how quickly I'm running through CR123a batteries. I just ordered a Malkoff M60 LED and was informed by Gene that running rechargeable batteries with his LED would have "dangerous" consequences. He recommended a "special battery carrier made for rechargables" and pointed me to CPF as a source for additonal information.

Before soliciting advice, let me explain my situation and what I'm looking to achieve. I'm a law enforcement officer and work patrol on the graveyard shift. I use my light throughout my shift for everything from illuminating vehicles during traffic stops to illuminating the inside of buildings while checking for people/items/etc. A few years ago, I purchased the Surefire M6 to replace the Streamlight SL20 that I had been using for years because I figured the more lumens the better, but $30+ per week in batteries is draining me. I need a general purpose light and am a big fan of LOTS of light. If I can't see it, it has the potential to hurt me. I'm looking for a light that can illuminate things at a reasonable distance as well as flood a room/hallway/building with lots of light. I'm willing to spend money to get quality equipment, but don't want to throw my money away on gimmicks.

I've looked at the Lumens Factory upgrades for the M6, but was scared off the battery requirements. I saw batteries ranging from 770 to 950 mAh, protected and unprotected cells, LiMn and Li-Ion, etc..... I had no idea what I was looking at and how to pick the right set-up. To make matters worse for me, my Department issued a warning against using Chinese-made batteries (it seems someone's light exploded and injured them) and I swore off buying anything not made in the USA.

I'm open to any advice, but would prefer to modify/upgrade my M6... it's been with me through some pretty nasty incidents and has a lot of sentimental value.

Thanks

 

[Erzengel]

Hello,

I'm sure You bought a MD 60 for Your M6, not an M60. If You want to operate it with rechargeables, there is at least one adapter for two 18650s. As the MD60 draws about 1 Amp from two 18650s, cells with with a capacity of 3100 mAh should work fine. The protected AW 18650 3100 mAh are mostly recommend here. For charging these I recommend the XTAR SP2 because it can charge two cells at 1 Amp and has got a very good technical review (at least here in Germany).
Two 3100 mAh cells should give You about three hours of runtime at full output. You can still use the Cr123 carrier as a backup solution or get a second adapter and a second pair of rechargeables if You are satisfied with this solution.
There are two basic security rules dealing with protected LiIon rechargeables in a quality charger:
Never charge them unattended or in an easy inflammable place.
If You use them in pairs, use identical batteries for the pairs, charge them together and always keep the same pair together (number them).

 

[Justin Case]

I am new to the forum and in need of some advice.

I have been using a Surefire M6 for a few years and have finally run out of patience (and money) over how quickly I'm running through CR123a batteries. I just ordered a Malkoff M60 LED and was informed by Gene that running rechargeable batteries with his LED would have "dangerous" consequences. He recommended a "special battery carrier made for rechargables" and pointed me to CPF as a source for additonal information.

Before soliciting advice, let me explain my situation and what I'm looking to achieve. I'm a law enforcement officer and work patrol on the graveyard shift. I use my light throughout my shift for everything from illuminating vehicles during traffic stops to illuminating the inside of buildings while checking for people/items/etc. A few years ago, I purchased the Surefire M6 to replace the Streamlight SL20 that I had been using for years because I figured the more lumens the better, but $30+ per week in batteries is draining me. I need a general purpose light and am a big fan of LOTS of light. If I can't see it, it has the potential to hurt me. I'm looking for a light that can illuminate things at a reasonable distance as well as flood a room/hallway/building with lots of light. I'm willing to spend money to get quality equipment, but don't want to throw my money away on gimmicks.

I've looked at the Lumens Factory upgrades for the M6, but was scared off the battery requirements. I saw batteries ranging from 770 to 950 mAh, protected and unprotected cells, LiMn and Li-Ion, etc..... I had no idea what I was looking at and how to pick the right set-up. To make matters worse for me, my Department issued a warning against using Chinese-made batteries (it seems someone's light exploded and injured them) and I swore off buying anything not made in the USA.

I'm open to any advice, but would prefer to modify/upgrade my M6... it's been with me through some pretty nasty incidents and has a lot of sentimental value.

Thanks

Unclear why Malkoff thinks that using Li-ion rechargeables (RCR123, also known as 16340) is "dangerous". The stock M6 battery holder connects the six 123 sized cells in what is called 3S2P. That means two sets of three cells are connected in Series, and then those two sets are connected in Parallel, hence 3S2P. What that does for you is give you 3*3.7V of total battery voltage, or about 11.1V, and about 2*550mAh of battery capacity, or 1100mAh (milliamp-hours).

Li-ion peak voltage should be about 4.20V (resting, fully charged). So the max battery voltage that the MD60 LED tower will see is 3*4.2V = 12.6V, which is still within the MD60's 14V max upper limit. So loading the stock M6 battery holder with 16340 Li-ion cells should work fine.

The Malkoff web site states that at 12V, the current draw is 620mA. If we assume the same current draw at 11.1V, you could get a total run time of about 1100mAh/620mA ~1.7 hours.

IMO, the main downside of this approach is having to load your battery holder with six cells. The upside is that you only have to buy the 16340 Li-ions. No need to get a new battery holder.

The alternative that Malkoff suggests probably is to get a 3x17670 holder from either mdocod or Fivemega on the CPF Buy, Sell, Trade forum. These holders will connect the three 17670-sized Li-ions in series (3S). Thus, total battery voltage will be 11.1V as before. The larger 17670 cells should have a capacity close to their rated capacity of 1600mAh. Thus, your run time with this configuration could be about 1600mAh/620mA ~2.5 hours.

The downside is that you have to buy a new battery holder, which could cost about $30-$40 plus shipping. Protected (meaning, the cell incorporates a small circuit board that can protect the cell from things like overdischarge, high current draw, and overcharge) 16340 cells from AW cost about $6 each ($36 total, plus shipping). Protected AW 17670 cells are about $10 each, or $30 plus shipping. So the Malkoff alternative will cost you more money, but give you longer run time. Lighthound sells AW cells. You can also find them on CPF Marketplace.

 

[Erzengel]

I recommend to go with two 18650s instead of three 17670s or six 16340s because they give You the longest runtime of all these combinations and it is always easier to handle a smaller number of rechargeable batteries.

 

[fiberguy]

I may be wrong here, but I read on this forum that "all 18650 batteries are made in Asia"

I would assume your dept. may be talking moreso about a ban on 18650 batteries, or rechargeable Li-Ion cells in general. Most of the explosions are Chinese made 18650's from what I understand, but you should probably check with the actual rules before buying Japanese Li-Ions, just to find you aren't allowed to use them either. If you swore off buying anything not made in the USA (good for you!), the above suggestions are a bit of a lost cause. I would say you need to look into a different light that uses either alkaline or NiMH cells? It would be that or keep paying the $30/week for batteries. Regardless, switching to Alkalines or NiMH definitely has its power and output disadvantages over lithium cells. Hope this helps!

 

[Erzengel]

All LiIon Cells I know are made in Asia. But there is a huge difference between some cheap chinese cells from ebay and A grade cells from Japan or maybe Korea. Every notebook or cell phone in Your department will be equipped with asian made cells. Does anybody know where the new Surefire rechargeables are made? The big safety question is the quality control. A protected rechargeable consists of the cell and a protection circuit. I don't know if there is a company in the USA which assembles protected 18650 cells and takes over liability for the risks. In Germany we have at least one company (Enerpower) which assembles protected 18650s with quality cells.

 

[Gene43]

IMO the 2 X 18650 holder seems the best solution. The lower the cell count, the lower the chance of mishap. The reason I discouraged the use of 6 rechargables is because of the much higher chance of one bad cell causing a mishap.

 

[oldways]

I would suggest replacing that M6 with a Malkoff Hound Dog/ MD4 body and 2 3100mah 18650. Thats what I did.

 

[Justin Case]

I forgot about the 2x18650 holder from mdocod. The main thing I don't like about my holder is the loose wire to connect batt- to batt+ for the series connection. The total energy from 2x18650 vs 3x17670 isn't dramatically different. The Malkoff web site says that at 9V, the current draw is 800mA. So if we assume 7.4V nominal from 2x18650, the draw is probably close to 1A. Using HKJ's excellent battery comparator, even the 3100mAh AW and Callie's Kustoms cells don't deliver the rated capacity. They look to be closer to about 2900mAh at 1A draw. AW's discharge curve for his 17670 cells suggest 1600mAh at 1A draw. So,

"3100mAh" 18650: Total energy ~2*3.7V*2900mAh ~21.5Wh

AW 17670: Total energy ~3*3.7V*1600mAh ~17.8Wh

The 3100mAh 18650 configuration could provide about 20% more total energy and thus 20% longer run time. But they are also about $20 each, or $40 total, vs $30 total for three AW 17670s. I suppose the choice depends on the value of total run time, this loose wire in the 2x18650 holder, any safety difference for two vs three cells, and the extra $10 for the 18650 cells (amortized over however many years of use). If the new 3400mAh 18650s perform up to their ratings, IMO now you are talking about a noticeable jump in energy (about 40% increase: 25.2Wh vs 17.8Wh).

If you try to keep the total battery cost the same ($30), then you might be looking at the AW 18650 2600mAh cell (about $15 each). HKJ's comparator shows a capacity of about 2350mAh at 1A draw. Total energy is thus about 2*3.7*2350 ~17.4Wh, which is basically the same as for the AW 17670.

 

[angelofwar]

Forget all the fancy mod's/upgrades, exoctic RC options/adapters, etc.. Keep it how it is, and get a Malkoff or Nailbender LED upgrade for it. And keep using the same batteries. You triple/quadruple the high runtime, plus, you can save your spent cells, and use them for outages at home (just make sure too keep the 6 that are used together, with each other). And welcome to CPF!

 

[nightowl415]

Thank you for all of the suggestions. I've decided to go with a new battery adapter and rechargeables. I ordered a 2 x 18650 adapter and 2 x 18650 cells at 3100 mAh. Thank you for breaking down the numbers and walking me through the process.

 

[nightowl415]

One last question regarding upgrading the M6... can anyone point me in the direction of where to find a replacement bezel for the standard crenulated SF bezel. The standard bezel does number on clothing when worn in a pocket. I'd prefer a smooth, rounded bezel. Something in a non-reflective color or coating would be ideal.

 

[kelmo]

Welcome to CPF!

Keep your eye on the Marketplace. You may have to buy a complete light (M3T, M4, or M6) and swap the bezels.

Or you could trade you bezel for a smooth one.