Wow! The Mag85 Is Awe Inspiring!

[GreyShark]

I built mine using a 4C Maglite host running on 3x AW protected 18650's. The runtime should be well over an hour. I realize there are brighter lights but this is really pushing the edge of what I can even use practically. It vigorously illuminates at about 200 yards and is painfully bright even from 100 feet away. While mine has a cammed reflector there is no point in using anything but a tightly focussed beam outside, there is so much light coming out this thing you don't even need the flood mode. Opening the beam up indoors or at very close ranges can help to make what you're illuminating less painful and actually visible through all the light. I used one of FM's stainless steel bi-pin holders to build in a little resistance to help with IMR's in the future and guard against instaflash. Nonetheless the beam is very white for an incan.

The thing was a piece of cake to put together since 4 C's are 200mm long and 3 18650's are 195mm long. I'm just using rolled up cardboard as a battery holder right now but a 3/4" schedule 40 PVC pipe would work perfectly if it was sanded down just a little. Other than that I clipped one loop off the tail cap spring so there was less pressure on the batteries and I rounded the end of the spring with a file so it wouldn't scrape up the base of my battery when I screw on the tail cap.

I like the 4C host because the slightly narrower body fits my hand better than a D body, it's long enough to give a burglar a good smackdown but still compact and light enough to tuck in my belt and walk around normally or throw in a pack. While I have no interest at all in stock Maglites I have to say they make great hosts! They're weather resistant, solidly made, the adjustable focus is nice and they are dirt cheap! I don't worry about knocking this thing around because I've got nothing in the body, even the borofloat lens is inexpensive, and the only parts that really did cost me anything are well protected within its thick aluminum hull.

My only question is, well, what the heck is the weird Maglite logo supposed to be??? :thinking: I really have no idea. My wife suggested it may be a dog's butt or maybe a porkchop.

I've got to say this is just about the best hundred bucks I've ever spent.

 

[Illum]

the mag symbol is a Ram head....I think

the Mag85 is the only light I use outdoors when I'm around the house. [I live in a wooded area] and occasionally I take it for a walk, keep it turned off around people, then turn it on when I'm some distance away. I almost always hear some exclamation. At least one person asked if it was a magcharger

3x18650 is a superb combination
at 3.5 Amps those 18650s are draining comfortably

I use the 1185 with eneloops in the mag and 17670s in the M6. Eneloops are getting hit with 1.8C and the 17670s at 2.2C...18650s are getting hit with only 1.5C after initial surge, which is pretty good if your looking for battery longevity.

May I ask what battery holder did you use for 18650s?

 

[gswitter]

Though I find myself opting for a P7 more and more, my 3C Mag85 still gets used more than the rest of my incans combined. The C Mag bodies are a really comfortable size for me to carry, and the combination of the "C" celll capacity and AW's soft-start/multi-level switch makes this Mag85 a great all-around light.

 

[effulgentOne]

How are you predicting over an hour of runtime?

A typical 18650 is 2.2Ah, and a mag85 draws maybe 3.5A, which would give you about 38 minutes optimistically.

Am I missing something?

 

[GreyShark]

3x 18650 is 6600mah. 6600 * .8 = 5280/3500 = 1.5 hours.

Since the batteries are stacked end to end and are only 8mm narrower than a C cell they don't really need a carrier like you see with D cell setups, just something to make up the difference in diameter. I'm going to turn down a section of 3/4 inch PVC pipe but right now I'm just using cardboard from a toilet paper roll. Not exactly very high tech, but it works.


Initially I plan on using an 1166 bulb as the low mode but the soft start may be in the future if I decide I want to make this one multi-mode.

 

[DonShock]

Current flow for batteries in series remains the same, it's voltage that adds up. So three 1860s in series (3.7V, 2200mAh) gives you a stack that puts out 11.1V with 2200mAh capacity. If they were in parallel, you would have a stack that was 3.7V and 6600mAh capacity.

 

[copperfox]

You beat me to it Don

 

[jabe1]

Mag logo... "a dog's butt".

 

[pete7226]

Your math is wrong, I have this setup, runtime is about 35-40 minutes. With 3 3300mah C cells you would be at an hour of runtime

 

[LuxLuthor]

How are you predicting over an hour of runtime?

A typical 18650 is 2.2Ah, and a mag85 draws maybe 3.5A, which would give you about 38 minutes optimistically.

Am I missing something?

Besides the obvious misunderstanding of serial/parallel configuration as it relates to mAh supplied, you also don't get all 2200mAh out of the cells. Actual continuous run time is more like 1700-1800mA at 3.5A Here was a test I ran at 5A where AW 18650 ran out at about 1420mAh You can extrapolate that it would perform a little better at 3.5A drain...let's say 1800mAh

1800mA/3500mA = 0.514
0.514 x 60 mins = 31 mins

​

In any case of the actual run time, yes the 1185 is awesome! The ideal setup is to use a soft starting regulated driver set to 11.2V
Your setup has resistance losses that has voltage starting below that level, probably <10V delivered to bulb, and dropping as cells drain.

 

[Illum]

completely missed LuxLuthors post


Too busy finishing it and left the house

 

[LuxLuthor]

heres the calculation of runtimes for 1185 setups

Eneloop: 2000mah
9xAA series will yield 10.8V @ 2AH
2000/3500= 0.571 Hours, or 0.571x60=34.7 Minutes before going kaput...and you really shouldn't drain it dry for any cells, nor will the cells maintain that sort of voltage at the end of their capacity to keep the lamp going, I average a decent runtime on Eneloops to be about 25-30 minutes before you'll noticing the lamp going orange

17670: 1600mah
3x17670 series will yield 10.8V @ 1.6AH
1600/3500=0.457 Hours, or 0.457x60=24.7 Minutes before going off. I usually limit my M6-1185s usage to about 15 minutes tops

18650: 2200Mah
2200/3500=0.628 Hours, or 0.628x60=37.7 Minutes

The only way I can think of where can run a 1185 for an hour without damaging the batteries is somethings thats 35AH + 15% of 35AH = ~40AH

If you manage to accomplish cramming a battery that size expect the 1185 to start a fire with the plastic lamp tower and [assuming its tailstanding] an explosion when everything drops into the battery bay below.

Mag's stock switch and towers [from the smell when I yank the adapter out to recharge] don't appear to be able to last through 30-35 minutes of a 1185 on full output, could be wrong though:huh::shrug:

You cannot take full listed mAh ratings on battery label. None of them are accurate for any battery. Then the available mAh drops further when increasing load is applied. See my previous post.

 

[bigchelis]

I dont want to hi-jack, but how does the runtime calculation change when you use parallel cells vs non-parallel??????


To the OP; what happened to the pictures. Show of the Mag85. I been thinking of a ROP or Mag85, but feel I do not have the savy to do it yet.

 

[GreyShark]

Current flow for batteries in series remains the same, it's voltage that adds up. So three 1860s in series (3.7V, 2200mAh) gives you a stack that puts out 11.1V with 2200mAh capacity. If they were in parallel, you would have a stack that was 3.7V and 6600mAh capacity.

That strikes me as odd. My LED lights run longer on 3 cells than 2 but that may be a function of the driver? I understand how a parallel circuit could have a higher discharge rate and lower voltage than an in series circuit, or how an in series circuit could have higher voltage and lower discharge rate than a parallel circuit but I don't see how in either case it would directly impact the total available milliamp hours stored in the cells. I'm researching the matter right now but I don't think I'll be satisfied till I do a runtime test. Unfortunately I'll have to wait a while for my batteries to fully charge for that.

 

[GreyShark]

In any case of the actual run time, yes the 1185 is awesome! The ideal setup is to use a soft starting regulated driver set to 11.2V
Your setup has resistance losses that has voltage starting below that level, probably <10V delivered to bulb, and dropping as cells drain.

I can live with a half hour of runtime since I tend to use my lights a few minutes on, then off a while, then a few minutes on again. I have plenty of opportunity to recharge. I certainly am very pleased with the performance. I don't fully understand all the intricacies of batteries and circuits but that is part of the charm of the hobby, having a project that encourages learning. I won't be happy till I understand exactly where all my mah are going and why.

 

[USM0083]

That strikes me as odd. My LED lights run longer on 3 cells than 2 but that may be a function of the driver? I understand how a parallel circuit could have a higher discharge rate and lower voltage than an in series circuit, or how an in series circuit could have higher voltage and lower discharge rate than a parallel circuit but I don't see how in either case it would directly impact the total available milliamp hours stored in the cells. I'm researching the matter right now but I don't think I'll be satisfied till I do a runtime test. Unfortunately I'll have to wait a while for my batteries to fully charge for that.

It does depend on the driver, but you'll find that for many LEDs, past a certain point more volts does not equal greater output. Rather, more volts equals lower draw off the batteries.

 

[LuxLuthor]

I dont want to hi-jack, but how does the runtime calculation change when you use parallel cells vs non-parallel??????

It is a good question. Batteries can be used either in series or parallel.

• In series, think of your old time 3 D cell Maglite. Putting in the D alkaline cells each with Positive terminal facing towards bulb adds together the voltage of each cell, but the stored capacity ("mAh") remains that of a single cell.

• In parallel, imagine putting 3 smaller diameter cells (think AA's for example) along side each other, and all facing the same way. Now imagine you connect the 3 tops (with a conductive plate), and separately, connect the 3 bottoms together.

These 3 batteries would now together be the height of a single AA cell, but now acting in parallel. In this example, you add together the stored capacity of each to get a new battery pack 3x mAh as if it is a new larger capacity single cell, but the 3 parallel pack still only has the voltage of a single cell.
​

I can live with a half hour of runtime since I tend to use my lights a few minutes on, then off a while, then a few minutes on again. I have plenty of opportunity to recharge. I certainly am very pleased with the performance. I don't fully understand all the intricacies of batteries and circuits but that is part of the charm of the hobby, having a project that encourages learning. I won't be happy till I understand exactly where all my mah are going and why.

Yes, like you say....it is almost never realistic to keep your light on continuously, and with intermittent on/off is very easy to make your light last longer than a 1-2 hour outdoor walk.

I had your exact same idea when I started at this website about how batteries worked. You just have to have fun with it as a hobby, read when you feel like it, ask questions, etc. This is one of the best online groups of people I have found.

One resource I found very useful, even if at first it was overwhelming is www.batteryuniversity.com where the author wrote it for beginners and intermediate level battery users. Just read as much as you want, and go back when you feel like it.

At some point, this other thread I posted (& in the pinned topics of interest at top of section) may be useful.

 

[GreyShark]

Thanks for the link!

I guess the best analogy I can think of is a man at a buffet. He may eat a lot of food, and he may eat it fast, but can't eat more food than what's available on the buffet. Even if he is eating at full capacity the amount of food available on the buffet hasn't changed. In this analogy I'd say the man represents the load, how fast he eats represents the volts, how much he eats per mouthful is the amps and the buffet is the mah capacity of the batteries.

 

[LuxLuthor]

It does depend on the driver, but you'll find that for many LEDs, past a certain point more volts does not equal greater output. Rather, more volts equals lower draw off the batteries.

That is an example of a type of regulated ("buck") driver.

The basic idea with a separate "regulation driver" is to have an electrical circuit that delivers an ideal voltage for a bulb or LED.

Most regulators reduce voltage/current that would be too high (and would blow your bulb), and assumes you are putting the higher voltage/current cells in your light...which gets stepped down to the ideal voltage. As the batteries drain from use, their voltage may drop below the ideal level, and the regulation driver either takes itself offline (allowing lower voltage to now safely "direct drive" the light), or shuts off the light completely.

A less common form of regulation is where a voltage is a little too low for the ideal setting you want, and the driver "boosts" the voltage up. There is less flexibility with this regulation technique, and mostly relates to LED's.

Some LED regulators have both the "Buck" & "Boost" capabilities...but there are limits on how the battery combination must be within the driver's range of operation.

 

[LuxLuthor]

Thanks for the link!

I guess the best analogy I can think of is a man at a buffet. He may eat a lot of food, and he may eat it fast, but can't eat more food than what's available on the buffet. Even if he is eating at full capacity the amount of food available on the buffet hasn't changed. In this analogy I'd say the man represents the load, how fast he eats represents the volts, how much he eats per mouthful is the amps and the buffet is the mah capacity of the batteries.

LOL! That is an original way to try and digest the subject.

I was picturing one of those hot dog eating contests. In that example, I would say the voltage is the force with which he is shoving them into his mouth, the current is how fast he can chew/swallow, and the plate of dogs is the mAh capacity of food.

So when fat people get their "jaw wired" keeping their teeth close together, even if you increase the force (voltage) of shoving the hot dogs in, the amount to be able to chew/swallow (current) is reduced. That is the idea of what the resistance in the parts of your light (springs, switch) does.

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