Mag85 rest time?

[AMD64Blondie]

I've got a new Mag85 (arriving within the next 2 weeks..hopefully).My question is,what do I need to do so I don't instaflash my new Mag85's bulb?
(Also,how long do I charge the batteries for?)

I've never owned a hotwire light before,so I'm sorry about all the questions.

 

[mr.squatch]

I'm an electrical noob so I don't have expert opinions, but I say get yourself a smart charger. I got a 28 dolla one that is red light when I'm charging and goes to green when it gets close and from then on just trickle charges. I try to not overcharge, I won't leave it on green more than 30 mins or so. I've yet to flash one hot off the charger even. Also get yourself a cheap voltmeter, with that you can test the pack voltage and not put a 14v fresh pack onto a 12v bulb and flash it. I think that's most people's mistake that leads to flashed bulbs. I just got my first mag85 too, it's awesome I'm not smart enough to be in charge of charging schedules and math, so i let the smart charger do it all for me Good luck, hope you like your new lite


g

 

[tussery]

It actually all depends on what parts you used to make your Mag85. For example as I found LuxLuthor pack with Elite 1700's @ 12.3V + KIU Socket = I could get away with throwing my FM battery pack with Sanyo 2500's in after a little rest and have no problem.

If you are using a FM socket and a FM battery holder with commercial NiMH's I wouldn't worry about resting the pack as the resistance will most likely save the bulb. It is still a safe practice to rest the pack an hour.

 

[RoyJ]

Also get yourself a cheap voltmeter, with that you can test the pack voltage and not put a 14v fresh pack onto a 12v bulb and flash it.

I thought the 1185 is a 9.6V bulb?

9 ni-mhs would be about 12.8V hot (1.43V even with my "smart" rayovac charger). I'm guessing that's closer to instaflash territory.

I've always wondered if an 8 AA pack, soldered (super low resistence), and all resistence fixes to the mag, would be safer.

Since the resistence is lower than holders, I'll bet the v-bulb is very close to the 9AA setup on a stock mag body, under load. The initial voltage would be significantly lower due to the one-less-cell.

 

[flashgreenie]

I believe 1185 bulb is 12V. 24hours rest period should suffice. Thats what I do.

 

[daBear]

I run my 1185 bulbs at 10.8v max. Don't know any way to push 12v to a 1185. LuxLuthor has a destructive bulb test in the hotwire stickey thread at the top of this forum. You might pick up a lot of good info there and also wait until the experts chime in on this thread for some accurate info. The 1185 is a 9.6v bulb and if your pack dumps an unloaded 12+v into the bulb it will go WHAMO every time @ $5 +/- every time.

 

[flashgreenie]

You are right, it is 9.6V. My mistake
http://www.walamp.com/lpd/webstore/detail.tpl?partnumber=01185-U&cart=1199448767585804

I just loaded a battery pack measured at 12.35V into my Mag85 not 5 minutes ago and the bulb is still intact.

 

[RoyJ]

You are right, it is 9.6V. My mistake
http://www.walamp.com/lpd/webstore/detail.tpl?partnumber=01185-U&cart=1199448767585804

I just loaded a battery pack measured at 12.35V into my Mag85 not 5 minutes ago and the bulb is still intact.

What's your host setup?

A stock Mag body + holder has a fair bit of resistence so your v-bulb is probably a good deal lower.

In the example I gave - a soldered battery pack with all resistence fixes to the body, probably would instaflash the bulb at that voltage.

 

[flashgreenie]

What's your host setup?

A stock Mag body + holder has a fair bit of resistence so your v-bulb is probably a good deal lower.

In the example I gave - a soldered battery pack with all resistence fixes to the body, probably would instaflash the bulb at that voltage.

you are probably right, I am using one of fivemega 9AA-3D adapter.
Assuming a current of 3.15A. Say the body+adapter resistance is about 0.800 Ohms, probably less due to voltage sag under load.
man, its been a while since I have to use those equations

 

[KingSmono]

I just built my first Mag85... I'm using Fivemega's 9AA-3D battery holder and SS socket, PowerEx 2700 batteries, stock spring and switch. I use a Smart Charger to charge the pack, and I let it rest until it's around 12.6 volts... haven't blown a bulb yet. YMMV

 

[TKO]

Check out the bulb life at 10.8V compared to 9.6V

http://www.walamp.com/lpd/webstore/...&L2=3.31952948576512&adj=5&partnumber=01185-U

 

[Cydonia]

Don't forget the option of Soft Start. It takes off that shock of the initial cold start up. AW's D Soft Start Driver adds amazing capability to a hotwire. I start up the Mag85 at 30% power to begin with - and find that this amount of light is enough for most tasks. A press of the button and you're at 60%... and another you're at full power. You could use every resistance fix in the book, even Pro Gold on every contact - and use your hotwire at only 30% and 60% untill the batteries have run down till it's safe to use 100% In a pinch you could even load up 9 alkalines and run it at 30% for a little light :sick2: - something that is ludicrously impossibe with 100% or nothing setting. Just some out of the box off the wall thoughts...

 

[mr.squatch]

I was just using the 14v vs 12v as an example, sorry I should have been more clear. I didn't know the flash voltage for the bulb for this particular 10.8v pack.


g

 

[Icebreak]

Definitely the different setups require different rest periods. Might be a good practice to try a long rest with progressively shorter test periods. That's if you don't mind blowing one lamp. Otherwise, measuring the volts of your pack will give you a good idea what is safe. Here are measurements taken from a Mag85 6C using 9 Gold Peak 2200 mAh 4/5 Sub C batteries:

12.86V on batteries only, no load with one hour of rest

12.29V at the tailcap, no load with two hours of rest.

11.79V at the tailcap, no load with two hours of rest and 1 minute of use.

11.49V at the tailcap, no load with two hours of rest and 5 minutes of use.

11.20V at the lamp, under load with about 7 minutes of use.

10.99V at the lamp, under load a few seconds after start up from the above condition.

10.86V at the lamp, under load from less than 1 minute after the above condition until 4 more minutes into the run.

Resistance and current are players. At the lamp, under load with 2 hours of rest and about 8 minutes of use:

3.41A at start up that drops quickly to 3.37A then eases down to 3.31A and stayed there for several minutes until I got board watching the meter.

Resistance and current aside, it's possible that KingSmono's suggestion of 12.6V is a safe and reasonable benchmark for a no load measurement for a rested NiMh power source for the Mag85 HotWire. Of course, YMMV.

TKO -

We don't often go the speed limit in this here burning tungsten forum.

 

[AMD64Blondie]

As it turns out.. I just got a
message from KEW,who is building my new Mag85..and he says he's using a KIU hi-temp socket.(how long do I need to let it rest before turning it on?)
(Note:I don't have my new light yet..but I'll update you when I do get it.)

 

[sb_pete]

This has mostly been aluded to by other posters, but to put it all together (i hope):

WA1185 is a 9.6v bulb, but for the Mag85 application it is usually overdriven to a "nominal" 10.8V (9 x 1.2V nominal NiMh in series) or 11.1V (3 x 3.7V nominal Li-ion in series)
This is more complicated though because these batteries don't come "hot off the charger" at their nominal voltages. NiMh will usually be 1.4-1.5V actual when "hot" from the charger. Li-Ion will usually be 4.15-4.2 "hot" off the charger. Hence a 9xNiMh can be 12.6-13.5V and 3xLi-Ion can be 12.45V-12.6.

The less resistance, the more of an issue this can be, especially with NiMh.

I use a 3D mag with an FM holder, Eneloop batteries (which frequently acheive 1.48v off the charger (Lacrosse BC-900), Gold tail spring, an FM gold plated ceramic bi-pin holder, and a switch which has been fully disassembled and liberally "De-Oxit"ized. That is pretty low resistance and I have only instaflashed one bulb in 4+ months of nearly daily use at work.

If you are using a welded NiMh battery pack like those made by LuxLuthor combined with you Kiu switch, then I would probably let it rest an hour. If you are using an FM battery holder, then I would worry less. FM holders are very low resistance, but obviously a welded pack is even lower.

Bottom line is that these bulb's are pretty robust and put up with alot. If you plan on one bulb every couple months and one set of batteries a year as the operating cost, then I think you will come out pleasantly surprised every time.

Hope that helps
-Pete

 

[Icebreak]

4 hrs.

 

[TKO]

TKO -

We don't often go the speed limit in this here burning tungsten forum.

Just posted for informational purposes . . . crank 'em up as much as you care to:thumbsup:

 

[RoyJ]

Don't forget the option of Soft Start. It takes off that shock of the initial cold start up. AW's D Soft Start Driver adds amazing capability to a hotwire. I start up the Mag85 at 30% power to begin with - and find that this amount of light is enough for most tasks. A press of the button and you're at 60%... and another you're at full power. You could use every resistance fix in the book, even Pro Gold on every contact - and use your hotwire at only 30% and 60% untill the batteries have run down till it's safe to use 100% In a pinch you could even load up 9 alkalines and run it at 30% for a little light :sick2: - something that is ludicrously impossibe with 100% or nothing setting. Just some out of the box off the wall thoughts...

Not trying to argue the benefits of the driver, but from a pure economical point of view, it doesn't make sense.

I'm going to overdrive a 20W, 6V bulb to 9.6V (8 AAs). At this level it'll perform much like the Mag85. The thing is, I get 15 bulbs for a little under $20, which means for the price of one hot driver I can grab about 70 bulbs.

I doubt a hot driver can save over 70 bulbs in its, or my lifetime. (remember with the driver you're still using up bulbs, on top of the ones you have to save to recover the initial investment).

 

[sb_pete]

I'm going to overdrive a 20W, 6V bulb to 9.6V (8 AAs). At this level it'll perform much like the Mag85. The thing is, I get 15 bulbs for a little under $20, which means for the price of one hot driver I can grab about 70 bulbs.

what bulbs are these and where are you getting them?
I'd like to try a few...