Rechargeable M4 setup - Would this work?

[FrogsInWinter]

Ok so if I get an M4 Devestator and attach two 1-cell extenders from Lighthound, I should be able to fit 3 18500 cells inside, right? 3 18500 cells at 3.7 volts comes out to 11.1 volts total. But fresh off the charger at 4.2 volts each, initially means 12.6 volts total. So is this set-up feasable or will I end up blowing the MN60 / MN61 bulbs with the extra 0.6 volt

? Thanks in advance.

 

[stuartyr]

The 3 cells will power the lamp assemblies just fine, buy 18mm cells won't fit, you will need to use 17mm cells.

When I was first using this combo, if the cells were hot from the charger, I would stick each one in my L4 fo rabout 45 - 60 secs just as a precaution to take the edge off the cells, but I don't bother now.... YMMV

 

[FrogsInWinter]

Thanks for the quick response and thanks for pointing out that I need to use 17mm cells and not 18mm cells. Do you use the MN60 or MN61 bulb in your setup? or both?

 

[glockboy]

Just bored the inside and put 2 18650 and used M3 or M6 bulb.

 

[duckpotatoes]

...augering M4's are the thing this weekend! Let the hot aluminum chips fly!
Rechargeable M4 seems to be a real natural!

 

[OutdoorIdiot]

FrogsInWinter,

I've never had a problem with 3 rechargeables powering an MN60 straight off the charger. Mind you, my cells never seem to come off at 4.2 volts - more like 4.1.

BTW, I didn't want to have to either re-bore an M4, or have an M4 which was too long, so I just used 1 extender, and I load it with 3 protected AW17500 cells plus a half-cell spacer. I get about 35 minutes runtime with an MN60 which is more than enough for my purposes, and I don't have to double-click to get it to light up. This configuration is not suitable for driving the MN61, but I'm happy with it for now!

 

[FrogsInWinter]

Thanks for the info everyone. Looking into it some more. I'm considering this setup:

1.) Leefbody C tail, M head, 2x18650, HA III
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=2610

2.) Two (2) MC123 1-cell extenders HA III
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=1292

3.) KT4 Turbohead
http://www.surefire.com/maxexp/main/co_disp/displ/carfnbr/250/prrfnbr/756

4.) Three (3) 18650 batteries

A little disappointing to hear that the MN61 probably wouldn't work too well with this setup though.

 

[Paul5M]

Why do you want three cells? :thinking:
Two cells are better Here're why:

I use AW batteries for this exercise and assuming the batteries are perfect and you don't want to mess with your torch.
Cost:
- 3x 17500 + MN60: $10 => $30 + cost of extender
- 2x 17670 + MN16: $10 => $20 + cost of MN16
Power:
- 3x 17500 + MN60: 11.1V, 1.65A => 18.32W
- 2x 17670 + MN16: 07.4V, 2.54A => 18.80W
Runtime:
- 3x 17500 + MN60: 1.1Ah, 1.65A => 40.00 minutes
- 2x 17670 + MN16: 1.6Ah, 2.54A => 37.80 minutes

 

[FrogsInWinter]

Thanks for breaking it down Paul5M. I wanted three cells because I was hoping to use the MN61 bulb with that setup but as OutdoorIdiot mentioned, the MN61 doesn't play nice with the setup in my third post. I'm assuming the AW cells are rated at 3.6V? I was considering pila or wolf-eyes cells.

 

[OutdoorIdiot]

FrogsInWinter,

I think the last setup you refer to, with 3 x 18650 batteries, stands a good chance of working fine with the MN61, particularly if the cells are unprotected. I think I've seen posts from other people that use a similar setup, though it would be nice to have someone verify that they do so.

The reasons I don't use my 3 x AW17500 protected cells with the MN61 are (1) The protection circuit will not allow the current - they cells cut out, and (2) The current drain would probably not be terribly safe anyway (about 2.85A on 1100mAh cells).

 

[FrogsInWinter]

Ack, I was afraid of that. I would prefer to use protected cells.

 

[Centropolis]

I am kind of reviving this thread because I just bought a M4 and have 3 MN60 bulbs. I've read a couple of threads regarding using rechargeables in a M4 but couldn't find the info I need.

This thread states that I can use 2 17670 cells with the MN16. But what about with the MN60? I assume if you can use 4 CR123s with this bulb, I can definitely use 2 17670 cells too? Am I stupid or am I correct?

Basically what is the setup I need to use a stock M4 with the MN60 lamp using rechargeables to save money?

 

[mdocod]

Basically what is the setup I need to use a stock M4 with the MN60 lamp using rechargeable to save money?

There is no configuration of rechargeable li-ion cells that will fit in an M4 that will run an MN60 properly.

You can severely overdrive it with 3 li-ion cells, or severely under-drive it with 2 li-ion cells. Both options are less than desirable...

Read the li-ion incan guide in my sig line for information on what cells fit where....

Also... I should note that a number of the points made in this thread over a year ago are false.

------------------------

Without making any modification to the body, you are going to be running 2x17670 cells. Yes, you could install a pair of 17670s in there and run an MN60, but it would be a total waste. The MN60 is about a ~10V bulb, a pair of li-ion cells will deliver ~7.4V on average. The "225" lumen rating from surefire drops to ~90 lumen if you power it on a pair of 17670s. An MN15 would outperform it in every way.

I understand you have MN60s you want to use. Please accept that your best course of action is to sell your MN60 bulbs and use the funds to by bulbs that are suitable for a pair of 17670s. An MN15, MN16, HO-M3T, or EO-M3T are all great options that can work on a pair of 17670s. I personally recommend the HO-M3T as the best balance of output and runtime and cell cycle life on a pair of 17670s for your setup.

-------------------------


Ok... there is one other option, but it is a totally stupid waste IMO...

You could run 3 AW protected RCR123s in there with a CR123 dummy cell with the MN60. The lamp would be overdriven on fresh cells, and would dim rapidly with a runtime of ~15-20 minutes, the cells would be taking a beating the whole way and require replacement every 50 full cycles give or take. I would say use IMR16340s to get the cell health and cycle life and safety margin up, but I'm afraid they would likely flash the bulb... The option of using 3 RCR123s seems like a waste to me because you are not using all of the space within the body for energy storage.

The extra cost/time involved with just diving into a proper configuration right now will save you a lot of headaches down the road and give you a much better user experience with a "rechargeable" M4 setup.

 

[Centropolis]

I understand you have MN60s you want to use. Please accept that your best course of action is to sell your MN60 bulbs and use the funds to by bulbs that are suitable for a pair of 17670s. An MN15, MN16, HO-M3T, or EO-M3T are all great options that can work on a pair of 17670s. I personally recommend the HO-M3T as the best balance of output and runtime and cell cycle life on a pair of 17670s for your setup.

Thanks for the great information. I appreciate the time you spent explaining to me.

One question about the EO-M3T and HO-M3T, the LumensFactory website indicates the runtime for these two lamps are almost the same. So when you say cell cycle life, I assuming you're saying that the HO version will last a longer. What are the lifespan hours on these lamps anyway?

UPDATE: Found info on their website. 20 hours?! That's not a very long time. I know it is putting out a lot of lumens but still......maybe I should look for a M4 LED conversion mod.

 

[mdocod]

Thanks for the great information. I appreciate the time you spent explaining to me.

One question about the EO-M3T and HO-M3T, the LumensFactory website indicates the runtime for these two lamps are almost the same. So when you say cell cycle life, I assuming you're saying that the HO version will last a longer. What are the lifespan hours on these lamps anyway?

UPDATE: Found info on their website. 20 hours?! That's not a very long time. I know it is putting out a lot of lumens but still......maybe I should look for a M4 LED conversion mod.

When I say cycle life, I am talking about how many charge cycles the cells will last. The more reasonable the load on the cells, the longer they will last (both in terms of runtime and how many cycles they will survive)... Matching 17670 size protected li-ion cells to the load of an HO-M3T is more reasonable for the cells, the EO-M3T is technically still well within safe discharge ratings for the cells, but it is closing the gap tighter on the maximum safe discharge rate.

approximated runtime and output comparisons for this exact configuration I am describing can be compared to your other options in the compatibility chart in the guide linked in my sig line.

FYI, SF bulbs are generally rated for 30 hours of operation. Having a lower bulb life generally can be associated with having a higher efficiency, (greater lumens per watt). The 20 hour rating on the LF bulbs is pretty standard in the industry of flashlight bulbs in normal applications. Actually using a bulb for a full 20 hours in a flashlight with 30-60+ minutes runtime (depending on various bulb/battery options) can actually take awhile. Most flashlight uses are short bursts or a few minutes at a time anyways, accumulating the full 20 hours takes longer than you might think... The ratings are generally made assuming that the bulb will be cycled on and off a number of times in it's life. Many users report getting far more bulb life than expected.

Eric

 

[nfetterly]

I've got an M4 that I'm looking at getting bored to take 18650s.

From FM I got the 2 x 18650, socket/reflector (MOP) and FM1794 bulbs ($10 each). The thing ROCKS. I had my M6 out the night before (with higher outpot bulb) - with the big head I would have thought it would have blown away the 2 x 18650 setup with "normal" C size head. It didn't from my memory of the night before.

I need to do a side by side comparison....

 

[NotRegulated]

I put together my own M4 with all Surefire parts but with a Leef 2x18650 C to M tube just so I could use 18650's. I'm running a LF E0-M3T bulb. The cells are AW's latest button top protected 18650's. This setup has decent throw and a massive hot spot. Incandescent goodness. Highly recommended.

 

[Centropolis]

I put together my own M4 with all Surefire parts but with a Leef 2x18650 C to M tube just so I could use 18650's. I'm running a LF E0-M3T bulb. The cells are AW's latest button top protected 18650's. This setup has decent throw and a massive hot spot. Incandescent goodness. Highly recommended.

I am thinking either getting two 17670 cells or a 2 x 18650 body...and a HO-M3T. I already have two 18650 cells...not AWs...hope they are safe.

Leefs are nice but are there any cheaper alternatives? I mean other brands that make decent bodies? $62 is a little too much for me to spend on a body at this time.

 

[mdocod]

For a body with the M threads on the business end to mate up up with your turbohead i think the leef is the only option...