Mag85 Resistance with Stock parts.

[Databyter]

I built a Mag85 a few weeks ago, I have a FM 9aa holder Powered with enelopes in a 3d body with a prc to bi pin brass adapter and of course a non stock reflector and window.

It is bright but I don't think I'm getting more than 700-800 lumens with a fresh charge based on comparisons with my TK40 which should appear less bright but starts out about even and goes downhill from there. I expect this may be due to me using a stock switch, or possibly my battery choice.

It's possible that part of the problem is that my batteries were going through their first conditioning cycles and with use it might well get better, same with the old switch that hasn't been used much and might be tarnished inside a bit (I pumped it a few hundred times hoping it would help).

I'd much rather maximize conductivity so that I could get 1200ish lumens to start and still get 800-900 as it settles down for the long haul.

Also I was wondering if I just kept stock parts and disassembled all contact points and coated it with progold or deoxit ( same stuff I hear) would I notice a perceivable difference in max brightness, or do I need to upgrade some more components?

I'm happy with the light. I use it as needed all week and recharge it on the weekends and although it is dimmer at the end of the week it is still effectively bright, much brighter than a stock mag. This because I conserve the on-time as much as possible, and mostly require only short bursts.

I believe I'm getting more than 30 minutes effective time possibly due to the resistance problem not drawing as much current(Silver lining). And 30 minutes must be a long time since I use the light all week without it going dim.

Any suggestions?

EDIT: Just to clarify what I'm looking for is a list of ways to decrease internal resistance with original parts and/or with other parts. I can live with what I have but over time I want to make this more top shelf.

 

[LumenHound]

The old Mag Switch Resistance Fix.. 1/6th stock! thread outlines the steps you need to take.

 

[Databyter]

Thanks Lumenhound. That looks like a big improvement.

Anything else guys?

 

[gswitter]

The tail spring is another source of resistance. There are threads here with instructions and pictures of how to work around it (basically, run low resistance wire from the top to the bottom), but my quick search didn't turn up an example.

Another option to reduce the resistance in the switch (and extend the runtime with PWM-controlled medium and low levels) is to replace the stock switch, stem and bi-pin adapter with one of AW's multi-level, soft-start switches.

 

[Illum]

mag85 resistance does have one benefit though, cells hot off the charger won't extinguish lamps.

Unless you have an IS or uses the light for some sort of intensity benchmark you won't notice much of a difference outdoors. I speculate a stock mag85 produces the same output as a resistance fixed mag85 with a dirty window.

I've never done resistance mods, but as an owner [or was an owner] of three mag85s, I never had issues with using cells $1.5V off the charger in them. I only cracked an 1185 once because I bent a leg in an S shape:shakehead

 

[LuxLuthor]

The tail spring is another source of resistance. There are threads here with instructions and pictures of how to work around it (basically, run low resistance wire from the top to the bottom), but my quick search didn't turn up an example.

Another option to reduce the resistance in the switch (and extend the runtime with PWM-controlled medium and low levels) is to replace the stock switch, stem and bi-pin adapter with one of AW's multi-level, soft-start switches.

Amazingly, he still has these posted here. Tailcap spring fix link. Others on top of page.

 

[Databyter]

Another option to reduce the resistance in the switch (and extend the runtime with PWM-controlled medium and low levels) is to replace the stock switch, stem and bi-pin adapter with one of AW's multi-level, soft-start switches.

I was looking at that. Kind of pricey but it looks well worth the money and would save me alot of time.

Also it would make the light more usefull for some low intensity needs. I usually have several other lights on me for that but for some things the mag would be better as a low intensity with cam set to flood.

Problem is by looking at the switch I'm gonna say the cam would be ineffective and this is something I DO use and need.

I use the flood for taking pictures and of course the spot for saving me quarter mile walks down dark paths.

You guys have given me food for thought and I appreciate it. Why do I get the feeling I'm going to have TWO mag 85's now one with each type of setup =).

 

[gswitter]

Problem is by looking at the switch I'm gonna say the cam would be ineffective and this is something I DO use and need.

I use the flood for taking pictures and of course the spot for saving me quarter mile walks down dark paths.

Yup. You can still focus the light using the head threads, but it's obviously not as quick and may not have the range of the cam focusing.

 

[Aircraft800]

How many amps are you pulling at the tailcap?

 

[Databyter]

How many amps are you pulling at the tailcap?

I haven't had much time lately to do any measurements although it would be interesting to measure current and resistance of various components before and after mods.

Hell I've been so busy it took me about 3 weeks to get to the post office last month and I was about a month behind on my bills and was supposed to send a thick borofloat to a CPF guy who I guess waited patiently because it was a freebie.

Now work has cut my hours so I'll unfortunately have a lot more time to measure stuff and piddle around, and a lot less money to piddle around with.

I'll check the amps next time the batts are close to median, right now I'm running a little on the low side and about to charge. What sort of current should I be pushing thru there?

p.s. I'm thinking about buying that switch just because it's so damn sexy. In the meantime I'm going to buy some soldering supplies, I have a choice of much too large and much to small in soldering irons right now and one of em runs off of 12 volts which is only convenient on the road. And once I'm well armed with the right tools I'm going to fix up my resistance points. Even if I get a switch I can use the modded stock parts on the next light I get.

 

[Aircraft800]

Roughly 3A on a fully charged pack. If you are significantly lower than that, then there are some issues. Cells that have a high internal resistance, poor switch, spring resistance, etc.

 

[Databyter]

I was looking around for wire the other day and since I recently moved the only sort of electronic junk yard type store that I know of in the area is a long drive. That would have been my first choice because there are just bins full of used components and miscellaneous wires and stuff ( A flashoholic's bonanza).
So I just went to radio shack hoping I would get lucky. I couldn't find any copper wire in the store but while I was there I got a new soldering iron.

While I was in the section I noticed some "de-soldering braid" this looks to be copper and although its flat I'm guessing (probably badly because I'm no electrical genius) that it's about 16 gauge equivelent.
Does anyone know if this is pure copper, also its not insulated, so it might be better suited for the tailcap spring bypass as opposed to the switch stuff.

I guess bottom line is if it works, it,.. uh works. But if I use high current bulbs I don't want this stuff getting hot etc..

 

[Aircraft800]

Well, it should work well since it is a oxide free copper braid. You should remove the flux afterward since some types are corrosive, but come off easy enough with Isopropyl Alcohol (rubbing alcohol). I used something that looks very similar, it was Slot Car Pick-up braid.

 

[Databyter]

I used the braid for both springs and used de-oxit liberally on battery ends and all switch contacts and the pin adapter etc..

When I first turned on the light I had the head on it (why wouldn't I?).

It almost immediatly got foggy inside the bezel so I removed the head and let the assy. smoke a while. what a pita.

Am I supposed to wipe off the excess residue the pro gold leaves or just let it be? I wanted a liquid I could dab on but all I could find on a shelf ( as opposed to online) was a spray so it gets all over when you spray it, I got smart and shot a bit into the tail cap and used q tips for some parts but it evaporates quickly.

What I noticd is it leaves a residue. So, for hot applications I don't care how good the chemistry is, stuff that smokes leaves dirty residue. My conclusion is that de-oxit type products should not be used around the areas that get hot. I suspect I will have to disassemble all this again and wipe off the smoke residue from the contact points I just cleaned.

Btw I am now getting 3.15 amps at the tailcap with a bat pack I've been using all week. I admit it seems a bit brighter it was a bit yellow last night because I've been using it so much, but after mod although im sure it still needs a charge, it is not yellow. So mission accomplished.

On a fresh pack at the beginning of a work week I expect I should get significantly more than the 3.15 Amps I'm getting on a used pack.

 

[Aircraft800]

9 cells x 1.2v = 10.8v x3.15A = 34.02 Watts

Just a rough estimate, 35W bulb, you've fixed your problem. Just don't wipe out that reflector! I've had new Bi-Pin sockets smoke before, wipe down the lens and cold bulb with isopropal alcohol to get all the residue out. You could probably run some over the reflector, but don't touch it with anything. I've cleaned it with distilled water and a Nitrogen gas blast.

You're now getting closer to instaflash, so be careful on a hot off the charger pack.

From LuxLuthors chart, the bulb lumens should be >1000 now.

 

[Databyter]

From LuxLuthors chart, the bulb lumens should be >1000 now.

Woohoo!


I left it smoking with head off last night till the batts were dead ( I was in the shower), and this morning, ( Just got home), I put the pack on the charger.

I must buy another FM pack, I'd like to have a spare, and with the enelopes I use it should stay pretty viable even a week after charge if I just put on the spare pack every week.

I sprayed pro gold even in the bi pin adapter and all over the tower assy, heh, guess I went a bit overboard.

I had an instinct about the reflector last night and just used cold water and the tiniest bit of dish soap on my finger tip to very lightly wipe it under running water, then I wiped it with a pre dampened paper towel ( to make it soft). It retained it's high luster.

Thanks for the help and suggestions. I didn't do the full wire bypass on the switch ( I still may I ran out of before work time) But I think I can live with what I have now. I think the switch tower job and tail job and the pro gold in the pack and switch probably gave me a few more watts :naughty: and even with the low pack I really noticed the difference in brightness and HEAT.

P.S. I know rechargable cells are always figured for 1.2 volts but my pack is giving me an extra volt or even after a few days of intermitant use so I'm thinking the enelopes are closer to 1.35 or so. I will do some measurements this week to be sure. So I'm guessing I'll be anywhere from 2300-1300 lumens (hoping and charging). Of course under load I have no idea, another thing to measure I suppose.

 

[Aircraft800]

The battery's will sag under a load to 1.2v, 1.35v~1.41v is no load. I don't think it's a good idea to run the pack all the way down, you shouldn't go lower than .9v per cell, so 8.1v on the pack. If you do, charge it ASAP. A slow charge is always better, it balances the cells that way. If you could maintain 10.8v to the bulb under a load, that's right where you would want it.

EDIT: That's a 30W rated bulb, 9.6v at 3.15A

 

[Billy Ram]

I just measured my amps at the tail cap with only a few mins run time on the charge and it settled down at 3.15 amps. I'm running 9xAAs /WA1185 and no resistance mods. This is a new build with only a few charge cycles on the batterys. The run times get longer with every cycle.
Billy

 

[Billy Ram]

Last night I decided to experiment with resistance mods. I first did the bulb spring mod alone with solder wick. "No ground leaf spring mod" This brought my amps at the tail cap up to 3.26A. This is a new switch and I couldn't read any loss in the grounding leaf spring. Next I did the tail cap spring mod using #16 wire. Surprizingly I couldn't read any differance. The only reason I can see is the tail cap spring being shiney new is being compressed against itself reducing the resistance. The bulb spring mod is a easy, worth while mod and the light may be a bit brighter. This light is Quite bright with a amazingly good throw for this power of light. I have to give credit to the Throw Master head having something to do with this.
Billy