Surefire 9p with Malkoff M61sho question

I just bought a M61sho for my 9p with intention of using 2 aw 17500. I got some nitecore 16340's with the nitecore I2 charger. Is it safe to use 3 of the 16340's with M61sho? I know it's rated up to 12v but this is all new to me. Also if its safe, which combo would give the better runtime? Would output be better with one vs. the other? Thanks guys.

:welcome:

Your 17500s and 16340s will typically be at around 4.2 volts each when fresh off the charger meaning you will have 8.4 volts with two cells and 12.6 with three. Therefore using the three 16340s would put you slightly above the voltage range for the M61SHO. Would it work? Maybe. Would I recommend it? No.

Two 17500s would provide greater runtime and less energy wasted as heat. Assuming nothing bad happens, I suspect three 16340s would generate a very (extremely) slight increase in initial output but you would probably need test equipment to even notice the difference.

Thanks for your answer. Would using the 16340's damage the M61sho?

I doubt it would hurt anything but since their voltage is higher than the manufacturer's specification it's not my place to say. For a definitive answer, just send an e-mail to Gene. He is good about answering questions such as this.

Three fully charged 16340s would have a no-load voltage of around 12.6V while 4 CR123s would be in the neighborhood of 13 volts. With either battery type the voltage will sag when a load is applied and will most likely get down closer to (or below) 12 volts.

I think the runtime with 2x17500 would be the clincher, slightly over 50% more runtime I'm thinking.

I've used this setup with the classic M60 and it's great - charging is often easier with only a pair of cells rather than managing three of them.

Reliability should be greater as well - I've had a LiIon protection circuit fail on me before, so having only two of them in the light will give less chance of that happening.

Guys, again thanks for your input. I think I will see if I can trade the 16340's if Gene says it's a no go. I just bought a M61 lmh and the M61sho so money is tight this week. You gentlemen are a wealth of information. This forum is awesome. I do have one other question, on another website selling the aw 17500 they recommend getting a 1.6mm spacer to put in between the batteries. Is this recommended by you guys? Again it would be 2 aw 17500 in a stock 9p body with the M61sho.
Thanks

You can use a spacer with 2x16340's but the running time will be reduced.

They specifically said to use a 1.6mm spacer with the 2 17500's.

Also just got a response from Gene and he said that running 3 rcr123a is fine.

Bigwilly said:

Also just got a response from Gene and he said that running 3 rcr123a is fine.

Click to expand...

There you go, you're all set.

If you will be using the light very often I think you will begin to see the advantage of the 17500 cells. I have no idea about the use of a 1.6mm spacer as I have never had to do that with any of my SureFire lights, and I run 17500s in a bunch of them. :shrug: Was there any additional context to the use described on that other website?

Here is what they say: "17500 batteries are 1.5 times the height of the standard CR-123a battery, so two of these batteries in series replace 3 standard CR-123a batteries in most applications. Purchase the 1.6mm magnetic spacer - below, they help the batteries make contact in the middle."

So if nobody recommends it, I'll skip it.

I'm sure they have their reasons for recommending that but I have had no issues with my AW17500s

Cool. But of course with my luck I'll need it. Lol.

Bigwilly said:

Here is what they say: "17500 batteries are 1.5 times the height of the standard CR-123a battery, so two of these batteries in series replace 3 standard CR-123a batteries in most applications. Purchase the 1.6mm magnetic spacer - below, they help the batteries make contact in the middle."

So if nobody recommends it, I'll skip it.

Click to expand...

I've used Malkoff dropins & 2xAW 17500's by themselves with no issues, so you'd be good to go.
I'm wondering if they're thinking about uprotected cells (i.e. slightly shorter) or the various generic LiIons that may have flat tops or something ... :thinking:

I just rechecked the website and it is for an AW 17500 protected cell that they recommend the spacer.

Thanks for your answer. Would using the 16340's damage the M61sho?

I talked to Gene and he said it would run fine. I received it yesterday and used it ladt night with3 16340's and it worked fine.