# Mag85 vs. Mag 5761??



## RichS (Feb 19, 2008)

In reading up on these two configs, I was under the impression that the Mag 5761 was somewhat brighter, or at the very least as bright as a Mag85. I already have a Mag85 - 3x18650 w/ low resistance tail cap - and it has amazing output. So when I read about the Mag 5761 being even brighter in a 2D format, I immediately turned my ROP into a 5761. I am using a FM 6AA > 2D battery holder with Eneloops. I have been told that Eneloops should power it just fine.

The only changes I made from the ROP config is the FM SS bi-pin holder, 5761 bulb, and a UTC in the tailcap to keep the bulbs from insta-flashing (below). BTW - huge thanks to Northern Lights and jimjones3630 for stepping me through this and answering all my questions. I haven't blown a bulb yet!

The question is - the 5761 (even on freshly charged Eneloops) is not as bright as my Mag85. The Eneloops measured about 1.4v each fully charged for a total of 8.4v before sag and resistance. It is close to the Mag85, but at best, the 5761 is still about 15% dimmer. They both have only one resistance mod done which is the tailcap. 

Do I need to use different batteries in the 5761 to realize the true output, or is it just not quite as bright as the Mag85?

* Pics of UTC tailcap spring mod*


----------



## jugg2 (Feb 19, 2008)

Is that a resistor in the tailcap? I run Eneloops fresh off the charger in my 5761 with no instaflash problems at all.


----------



## RichS (Feb 19, 2008)

jugg2 said:


> Is that a resistor in the tailcap? I run Eneloops fresh off the charger in my 5761 with no instaflash problems at all.


Yep, it is. I read a bunch of posts talking about the need for an NTC or some soft starter. Well, as long as it's not giving me much extra resistance I guess it won't hurt to leave it. Have you had the 5761 for a while, or just been lucky??


----------



## EvilLithiumMan (Feb 19, 2008)

I have both the 85 and 61. Both use the AWR Hotdriver. The Mag85 is set to 10.5v and the Mag61 to 6.9v, so both are set to about .3v lower than what is considered nominal. Both have the low resistance tailcap spring mod. Both run on AW's protected 3300ma Li-Ion cells. Both have SMO reflectors. With my setup, they are both nearly even in brightness, with a slight edge for the Mag61. The biggest difference, however, is the color temperature. As bright as the Mag85 is, it still retains a pretty distinctive yellow incandescent tint. The Mag61 is much whiter. Not LED white, but pretty damn white for an incandescent.

Only my opinion, but if you want something brighter than the Mag85, a Mag61 won't be that much of an improvement. Better go for a 50 or 100 watt overdriven lamp.


----------



## jugg2 (Feb 19, 2008)

RichS said:


> Yep, it is. I read a bunch of posts talking about the need for an NTC or some soft starter. Well, as long as it's not giving me much extra resistance I guess it won't hurt to leave it. Have you had the 5761 for a while, or just been lucky??


 
I have only been running this setup for a week or two, but I have run around 10-12 sets of batteries through it. I have also pulled batteries directly out of the charger and put them in the light-not even 1 minute worth of rest time. But, I do not have any resistance mods, the light is 100% stock. Also, I am running Kai's bulb adapter-not Fivemega's.


----------



## Dung Beetle (Feb 19, 2008)

It looks like the NTC is installed incorrectly? Maybe someone who is more knowledgeable can look at how you connect this? 

I think it looks electrically shorted and has no effect.


----------



## Anglepoise (Feb 20, 2008)

I would add two things.

I do not believe an NTC is needed when using 6AA>2D and the 5761.
Even hot off the charger, the under load voltage sags quickly and will be around 6.8 volts.

For the NTC to work correctly, all the current must flow through it. In the setup as photographed ,it is in parallel with the spring. Sort all this out and the output from the 5761 should go up a little.


----------



## Jay T (Feb 20, 2008)

Anglepoise said:


> I would add two things.
> 
> I do not believe an NTC is needed when using 6AA>2D and the 5761.
> Even hot off the charger, the under load voltage sags quickly and will be around 6.8 volts.



I sent one of mine to light bulb heaven (or hell) last week with 6 fresh charged titanium 1800s


----------



## jugg2 (Feb 20, 2008)

Jay T said:


> I sent one of mine to light bulb heaven (or hell) last week with 6 fresh charged titanium 1800s


 
I guess they give more Vbulb under load than Eneloops.


----------



## Jay T (Feb 20, 2008)

jugg2 said:


> I guess they give more Vbulb under load than Eneloops.



+ Kiu socket, tailcap spring mod and progold in the switch.


----------



## RichS (Feb 20, 2008)

Anglepoise said:


> I would add two things.
> 
> I do not believe an NTC is needed when using 6AA>2D and the 5761.
> Even hot off the charger, the under load voltage sags quickly and will be around 6.8 volts.
> ...


Thanks - I must have misunderstood the directions I received. So I should be safe to just eliminate the UTC, and just run the copper braid from the top to bottom of the spring as a resistance mod then?

Could the UTC in the spring be reducing the output?


----------



## jimjones3630 (Feb 20, 2008)

Hi Rich,

Wired parallel it may be reducing output but I doubt it. I would try it with out ntc and without copper braid in the tailspring first. Then if works proceed to the tailcap resistance fix but would only do one at a time as has been my experience easy to over do it and start blowing bulbs.

jim




RichS said:


> Thanks - I must have misunderstood the directions I received. So I should be safe to just eliminate the UTC, and just run the copper braid from the top to bottom of the spring as a resistance mod then?
> 
> Could the UTC in the spring be reducing the output?


----------



## RichS (Feb 20, 2008)

jimjones3630 said:


> Hi Rich,
> 
> Wired parallel it may be reducing output but I doubt it. I would try it with out ntc and without copper braid in the tailspring first. Then if works proceed to the tailcap resistance fix but would only do one at a time as has been my experience easy to over do it and start blowing bulbs.
> 
> jim


Thanks Jim - live and learn. I'll just try it without for now and go from there. So I guess it wasn't as easy to use the $1 UTC soft start as I thought...is it obvious that I'm new at this?..


----------



## jimjones3630 (Feb 21, 2008)

Rich, your welcome.

we all were new at this at one time. 
jim



RichS said:


> Thanks Jim - live and learn. I'll just try it without for now and go from there. So I guess it wasn't as easy to use the $1 UTC soft start as I thought...is it obvious that I'm new at this?..


----------



## LuxLuthor (Feb 21, 2008)

Rich, as JJ says....we all started at the beginning.

If you want to use the NTC, as Dung Beetle & Anglepoise have pointed out you need to put it in series somewhere. If you want it in the tailcap, you need to insulate the spring from making contact on battery end with a round piece of plastic or plain PCB board. Then insert one leg of NTC through center of that insulator, and solder it to a new, small copper disc that will become the contact plate for battery (instead of spring). Solder other leg of NTC to the tailcap spring.


----------



## Anglepoise (Feb 21, 2008)

Rich,
photo shows the white insulating material so that the top of the spring does not touch the rear of the battery holder. The connection comes down the center in a wire and then attaches to the NTC and or fuse at the bottom of the cap, and then goes to the bottom spring loop.


----------



## RichS (Feb 21, 2008)

LuxLuthor/Anglepoise,

Thanks so much for clarifying this setup - and the excellent pic to demonstrate. Makes complete sense now. Anglepoise - did you make that white disc at the top of the spring? Very nicely done! Do you sell those by any chance??

LuxLuthor - you had the 5761 listed a couple of slots above the Mag85 in your most powerful mods list. Is it that much brighter than the Mag85 with your setup? What batteries are you using. I am just assuming at this point my Eneloops are not giving me the full potential of this bulb.

Thanks again for all the help. Here goes my 2nd attempt...


----------



## IcantC (Feb 22, 2008)

Very nice info here, sorry to go OT, but what kind of runtimes are you seeing for the 5761 using Eneloops?


----------



## RichS (Feb 22, 2008)

IcantC said:


> Very nice info here, sorry to go OT, but what kind of runtimes are you seeing for the 5761 using Eneloops?


I just built mine a short time ago and haven't had it out on a long run yet. I'm taking it with me on a trip to Brown County Indiana next week, so it will definitely be seeing some long runs soon..


----------

