Mag 5761 (Mag61) Questions

[digitaldave]

I've recently been thinking about finally putting together a modified Maglite, so I've been doing some reading around and one option I'm looking at is the Mag 5761 (Mag61) as described here fore example. The suggested battery is AW's C sized Li-Ion cells, in a 2C Mag body. I have a couple of questions....

1) According to the AW sales thread on CFPMP, these are currently out of stock 🙁. Short of getting hold of some used ones (not something I'm keen to do), are there any other alternatives in the C size?

2) LuxLuthor's Most Powerful Maglite Mods List suggests you can also use 18650 batteries as alternatives. How many of these alternatives would I need? I guess you'd need 2x18650 to get the voltage, will these fit in a 2C body?

3) Any idea what sort of run time I could expect from the AW C batteries, and the 18650 setup?

Thanks,

Dave.

 

[DM51]

The 5761 draws ~5.5A, which is ~2.5C for 2x 18650 cells. This is too much for extended running on regular LiCo cells, and the high-current protection will also be a nuisance as you will probably need multiple clicks to start it up.

You'd do better to get a couple of IMR 18650s, which could easily handle that current; however with these cells you could have a problem with instaflashing the bulb, as the voltage sag will be less.

To calculate run-time, divide the capacity (Ah) of the battery by the current (A), then multiply by 60 to get the time in minutes. This gives you the absolute maximum possible; however you should bank on using only 80% of that, as it is not a good idea to run LiIon cells down to empty.

 

[BSBG]

DM51 gives good advice.

I am running two Sony LiMN cells in a bored SF M4 body with a 5761 (finally found one that fits!) and it is spectacular for about ten minutes then begins to dim noticeably.

The C cells don't fare much better in my opinion as after 10-15 minutes they have dimmed. It is still bright mind you, but the 'wow' factor drops considerably, especially if you have something to compare it to.

In a basically stock Mag, you probably have enough resistance to run the IMR18650s without instaflash, but no guarantees. Using AW's driver with the soft start would help as well.

 

[warx23]

I built a mag 61 a while back and its alot of fun to play with. Ive not run it longer then 5 minutes or so I haven't noticed the sag. I'm using 2 x c AW's. It takes 2 clicks to fire up also. Here is a little animated gif I made to compare a 6p, p7 mag, the mag 5761 and the big daddy 623.

 

[digitaldave]

Thanks for the replies 🙂.

My plan was to use the AW soft start switch whatever batteries I end up using. Would this still risk instaflashing with IMR18650 cells, or would the soft start facility mean that it would run OK? If I go the 18650 route, then I would rather use the regular ones for slightly longer runtime (don't laugh 😉), but if they are going to be trouble however even with the AW switch, then I'll go for IMRs.

The reason I was looking at using 18650s is that they are more easily available than AW's C cells (plus I could use them if I do a P7 or MC-E mod), but from the sound of things, it might be better to wait for new C cells to become available or get some second hand. These would mean slightly longer run time (IIRC these are 3300maH vs 2200maH for 18650 and 1600maH), and would only require a tailcap spring mod to get them to fit whereas 18650s would need a sleeve as well as tailcap modding.

Dave.

 

[BSBG]

The standard AW 18650s will not power up the 5761 - too much current draw. Therefore, the IMRs, or similar alternatives are your only option in that cell size. Higher capacity is nice for longer run time, but just carry a couple of spare cells 😀.

I think you will be OK with the soft start, but you never know. I am having no issues with the 5761 using 2 Sony 18650s with no soft start.

Member Download sells a kit with a sleeve and a couple of other items that make the 18560s work in a 2C - check the B/S/T for his post.

 

[digitaldave]

To be honest, I'm not expecting much run time as this will be mainly for the wow factor and because DIY stuff like this is fun 🙂. So IMRs should be OK, but it would be nice to have longer run times if possible. I'll have a look in the batteries forum for more info, thanks 🙂.

I just checked out the download mod kit, the sleeve should do the job nicely. I'd read that the AW soft start switch is a little shorter than the standard one, so hopefully the actual extender ring won't be needed...

Dave.

 

[Neubauej]

As an alternative idea, a magcharger with a FM 34mm extension plus one extra 1/2 d from another stock magcharger pack, and viola. Built in charger, and half an hour runtime too. Just remember to let the cells rest after charging or you will blow the bulb.

As a bonus, the stock magcharger bulb driven at 7.2v is very white, reasonably bright (I would guess 400ish lumens) and runs for 2+ hrs...

 

[cernobila]

The suggested battery is AW's C sized Li-Ion cells, in a 2C Mag body. I have a couple of questions....

....pity that it has to be the 2xC body. I have the 5761 in a 2xD body with the AW soft start/three level switch and 2x Kai D Li-Ion cells, works perfectly with a very nice beam.

 

[digitaldave]

Apologies for digging up my old thread, but I've been out of things for a while. However, I've just noticed that AW has some IMR 26500 cells that look like they would be a good option. Have I got the right idea with these cells?

Dave.

 

[Benson]

Apologies for digging up my old thread, but I've been out of things for a while. However, I've just noticed that AW has some IMR 26500 cells that look like they would be a good option. Have I got the right idea with these cells?

Dave.

Yeah, only "issues" with those is the risk of flashing due to lower internal resistance, and their 2300mAh capacity; since you have the soft-start, they should work great, but the runtime will be kinda short -- at 2.3Ah, they should last about as long as LiCo 18650s.

If you don't mind unprotected LiCo cells, you might prefer the "5000mAh" 25500s from DX, which get closer to 3Ah capacity (and would also be fine with a stock tailspring). I don't remember whether AW's switch has low-voltage cutout, but I have no trouble noticing the yellow shift, so I'm fine with them.

BTW, I modded the spring anyway (even though it worked stock) so that an 18650 can drop down through it, and it now accepts 2 of AW's unprotected 18650s nicely without the MagRing proper (but still using the foam pad, braid, and tube from the MagRing kit). So I drop in either the 18650 tube and 2 18650s, or just 2 25500s, screw the tailcap in, and I'm good. If you do this (since you have a soft-start), IMR26500s would also work fine in the same setup -- 3 battery types, no real changes to the light needed.

 

[Crenshaw]

I have some thoughts of building a short running high wow factor 5761 light in a FMD26,a surefire c2, running 2 IMR16340s.....

will it instaflash hot off the charger? i checked luxluthor's charts, and it says 7 or so volts will instaflash, so will there be enough internal resistance in a C2 to cut off a volt or so from the 8.4v hot off the charger batteries will have?

Crenshaw

 

[gswitter]

IMR16340 Specifications :

Nominal Voltage : 3.7V
Capacity : 550mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 1.5A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 8C
Operating Discharge Temperature : -10 - 60 Degree Celsius

8C for a 550mAH cell is 4.4A. The 5761 will draw over 5.5A.

 

[Crenshaw]

so no then? 🙁

how about 3 IMR and WA11185 bulb?

Crenshaw

 

[gswitter]

I've run an 1185 on 3x IMR16340s, and an 1111 on 2x IMR16340s - no problem, no soft start needed.

I haven't tried either bulb on larger IMR cells myself, but I've read neither bulb can handle IMR18650s or IMR26500s. I'm still curious about IMR18500s - an 1111 on 2x IMR18500s could be nice.