How To Mod a Maglite P7 - 38 PICS

oldskoolsmith

oldskoolsmith

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Absolutely. I gutted an old PSU to make use of its metal case a couple of months ago. First thing I did was cut all the wires off. Be aware, that the insulation on the wires is PVC and will melt if they get too hot. Don't let that stop you from using them. You've got a big bundle of wire in different sizes that didn't cost you anything. The majority of wires should be 22awg. This is actually larger than the wire I've used (24awg) in my P7 mods. It will be more than sufficient to handle the current required to feed a P7.

Sorry about the late reply, I really appreciate the information. I wanna give a huge thank you to all of you. I've read through this entire thread twice now and I've been learning to solder fixing some electronics that were headed for the trash if I couldn't get them working, I'm feeling more confident and thinking I should add a driver to my first P7. This brings up some questions, I'm hoping to double check what I've read on this thread.

I've got a D-bin and heatsink in the mail along with nimh batteries and I've got spare 3 and 4 D maglites.

1. Would the following driver be appropriate to run on 3-4 nimh batteries as well as alkalines if necessary?

http://www.shiningbeam.com/servlet/the-132/3-dsh-Mode-Regulated-Circuit-Board/Detail

2. If so, is there any way I could use something like a SharkSink D to heatsink it to the body? I'm worried that I can't because it looks like there are wires on both sides.

3. What are the connectors used in the 4th picture on the following thread? Are there any online stores that have these? It looks like there is one type for the separate wires from the switch and another for the two that go to the LED.

http://www.candlepowerforums.com/vb...g-Pewter-Shark-Buck-3A-(Price-Drop)&p=3142621
 
LEDninja

LEDninja

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4*NiMH give you 5.4V dropping to 4.8V.
3*NiMH give you 4.05V dropping to 3.6V.

The shining beam circuits use AMC 7135 IC chips as controllers.
From this thread it can be seen the 7135 circuits produce max output only at 4V and above. They still work at below 4V but at reduced output.
http://www.candlepowerforums.com/vb/showthread.php?192925-AMC7135-Specs-Inside-**UPDATE**

I would recommend 4D with the shinning beam circuit and direct drive with the 3D.
 
Justin Case

Justin Case

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From this thread it can be seen the 7135 circuits produce max output only at 4V and above. They still work at below 4V but at reduced output.
http://www.candlepowerforums.com/vb/showthread.php?192925-AMC7135-Specs-Inside-**UPDATE**

That is an incomplete conclusion and can lead to an erroneous battery configuration approach.

First of all, the test data in post #1 is for a Cree XR-E Q5 with a fairly high Vf. So of course, Vbatt for regulation will probably be around 4.0V.

But now look at post #30, which uses a Seoul P4 that has a lower Vf. Now Vbatt for regulation is down to ~3.6V.

Finally, go to post #41, where a 1xAMC7135 test is conducted (0.35A drive nominal) and the protection diodes are removed. At such a low forward current, the SSC P4 Vf is probably around 3.0V or lower and it shows. Now Vbatt for regulation is at least 3.4V and most likely lower (the test didn't go low enough for Vin to test the hypothesis that removing the protection diodes will decrease the required Vbatt to reach regulation -- see my discussion in post #44).
 
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oldskoolsmith

oldskoolsmith

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That is an incomplete conclusion and can lead to an erroneous battery configuration approach.

So the driver will work with 3 or 4 nimh or alkalines to power a p7, but the efficiency of 3 vs 4 nimhs is the problem being discussed?

Is there any heatsinking needed for this board, especially if it is running 4 alkalines (6V)?
 
Justin Case

Justin Case

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So the driver will work with 3 or 4 nimh or alkalines to power a p7, but the efficiency of 3 vs 4 nimhs is the problem being discussed?

Is there any heatsinking needed for this board, especially if it is running 4 alkalines (6V)?

I doubt that alkalines can deliver 2.8A at say 3.6V. You need NiMHs.

Efficiency is a secondary, or even tertiary, factor. In my mind, the primary issues are running in regulation, and running in regulation for a decent amount of time.

What that means is delivering enough Vbatt to reach regulation and to stay in regulation as the cells discharge and their voltages drop.

Read my post #44 in that AMC7135 thread. You need to satisfy two criteria -- Vf > 2.7V (with the reverse polarity diodes removed), and Vbatt,min > Vf + 0.12V. The first criteria should be no problem. At 2.8A drive, a P7 should have a Vf of at least 3.2V.

For the second criterion, Vbatt,min > perhaps 3.3V if you have a low Vf P7 (will be more if you have a higher Vf emitter). In reality, you probably need a few tenths more because of parasitic resistance in your flashlight, due to things like contact resistance (e.g., springs, cell-to-cell). So let's say that your Mag has a total parasitic resistance of 0.1 ohms. At ~3A, that is ~0.3V drop. So, you might need a Vbatt of about 3.6V to reach regulation for this hypothetical case.

Based on Silverfox's NiMH shootout data, 3xD Accupower NiMH (at least the Accupowers that he tested) can hold over 1.2V per cell at 5A draw. So those cells should give you near-max run time in regulation at the ~3A draw of an 8x7135 driver.

But if your P7 has a high Vf such that you need a Vbatt,min of say 3.9V, just to pick a value that is unfavorable, then you will need your cells to hold at least 1.3V under a 3A load. Looking at Silverfox's D Accupower curves, you can't get there from here, and so 3xD NiMH is out. You will need 4xNiMH to reach regulation and run in regulation for a satisfactory amount of time.

Also note that if you plan to use 3xAA Eneloops in D shell holders, the cells probably won't be able to hold above 1.2V per cell for very long and thus your run time in full regulation will be short. So, you will probably need 4xAA Eneloops for this batt configuration.

Alternatively, you could drive the P7 at a lower drive current, say 2.1A with 6x7135. At the lower drive current, LED Vf is also correspondingly lower and might allow you to use 3xNiMH, when you would have needed 4xNiMH if you chose an 8x7135 driver (2.8A).

To assess your situation, you need to be able to determine your LED's Vf at the relevant drive current.

Once you've established how many cells you need to run and stay in regulation, you're all set (assuming that Vbatt doesn't exceed the Vin rating of the 7135). Now efficiency comes into play. For the 7135, efficiency is essentially Vf/Vbatt. If the amount of waste heat isn't too bad, you might get away with no thermal management of the driver. IMO, if the waste heat starts to exceed 1W, I'd start to consider heat sinking the driver.

The large tab on each 7135 chip is the desired contact point for heat sinking. But, sinking to the 7135 case is better than nothing and probably easier to do. I'd probably use various convenient pieces from copper plumbing (easy to cut, bend, file, and shape) to thermally glue to the 7135 chips and then sink (thermally glue) the copper to the Mag tube.
 
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oldskoolsmith

oldskoolsmith

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Thanks! I've looked up how to do the copper plumbing heatsink for the drive, which it seems like I'll need if I use 4 cells, doesn't seem too bad.

Is any modification to the driver necessary? The LED says 3.50 - 3.75V

The batteries I'll be using are 4 of these:

http://www.zbattery.com/NiMH-D-Cell-10000mAh-1-2V-Battery

Eventually I'd like to get some LSD cells, but those will have to do for now. If I end up without a way to charge those I may have to toss in alkalines, but I realize they won't work nearly as well/long, I'm just hoping they won't damage anything.
 
Justin Case

Justin Case

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Ideally, you should actually measure the LED's Vf at the drive current of interest. But if you are intent on using 4xNiMH, then it doesn't matter. The actual forward voltage for any Vf-bin P7 will be sufficiently low for your battery configuration. I don't know anything about those zbattery cells. Assuming they are good quality, there should be no problem using four of them to drive your P7. You have plenty of Vbatt. I'd probably heat sink the driver. Alkalines should not damage anything. You just won't run in regulation for very long. But I bet you'll still get decent output for a little while. The way the 7135 drivers work, overall run time will be very long. It's just that you'll get steadily decreasing output with alkalines. With good D NiMH cells, the driver will stay in regulation for basically most of the run time of the cells and you'll get constant (and high) output.

You can remove the reverse polarity diodes from the driver if you so desire and replace them with short sections of wire.
 
oldskoolsmith

oldskoolsmith

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Plumbing heatsink for a D size? What kind, size, when, where, etc.? I'd love details!

Rich

I'm buying a place so it's been tossed in a box for a while.
The idea is to buy a 35mm copper tube then cut a tab big enough for the driver, fold it 90 degrees and thermal paste the driver to the tube and the tube to the maglite body.
 
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cyber5

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Wow. I've been reading this forum for like 14 hours now. This is my first post, as I wanted to let the OP know that his photographs are awesome and the detailed instructions are great.

I never knew there was such a "big" flashlight modding community, or how incredibly involved and fascinating it all is. I will be exploring more, for sure!
 
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free_umi

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Now sufficiently motivated to try tinkering instead of just reading. Whats the worst that could happen...... ;-)

Umi
 
jamie.91

jamie.91

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Hi, doin my first mag mod:thumbsup:

Its a 2D mag, what battery configuration should i run, i dont want to use AA's, i dont know the number thing but can i not get D size lithiums or something?

My plan at the moment is direct drive but if there is 1 simple driver i can use i will, i want runtime and simplicity, not charging 8 AA batterys every time, 1 or 2 big cells would be better

Thanks for any help
Jamie
 
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simplec6

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Sure buddy, a 32600 or 32650 will fit your in a d mag. If you want to direct drive you'll just want one lithium ion battery. So you'll need a spacer for the space between the spring and the 32650
 
jamie.91

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Thanks for the reply, is it safe on one of those? Not drawing to much power or anything? I know 2 will overdrive it to much butwill one be enough ? How many lumens and how long will the runtime be?

I have so many questions lol

Many thanks
Jamie
 
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forrest

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I've built several of these 3d mags with the p7's now I need some more p7's. Anybody know where to get some DSWOJ or dswoI's??? checked kaido and deal ext...Can't find them anymore :confused:Thanx!
 
Justin Case

Justin Case

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Thanks for the reply, is it safe on one of those? Not drawing to much power or anything? I know 2 will overdrive it to much butwill one be enough ? How many lumens and how long will the runtime be?

I have so many questions lol

Many thanks
Jamie

The amount of current drawn by the P7 is dictated by the LED's If vs Vf curve. A typical curve is shown in the SSC P7 datasheet. It is best to measure what LED Vf you have when the LED is driven at the desired drive current. A bench power supply can be useful for this purpose. You operate the supply under voltage regulation and observe what voltage setting is required to deliver 3A to the LED. That is your target Vf. The datasheet gives typical values for Vf. IIRC, depending on Vf bin, it could be 3.25V-3.50V or 3.50V-3.75V at 3A drive.

Now, you have to consider your battery supply, presumably a single Li-ion. The Li-ion will start out at 4.2V (assuming a fresh cell charge to 100% capacity), sag with some degree of rapidity to some quasi-steady state voltage (say 3.7V), and head downhill to depletion (say 3.2V or whatever).

If the voltage sag from 4.2V to QSS is slow, then you are overdriving the P7 for that amount of time, since the Vf at 3A is less than 4.2V. The P7 might not like that and you should use a voltage drop resistor.

If the Li-ion sags "immediately" to say 3.7V, then you *may* be ok, depending on the LED Vf at 3A. If you have a low Vf LED, say 3.3V, then you still need a resistor. Unless you have heat sinking sufficient to handle to overdrive.

The challenge is picking the Vbatt to use to calculate the value for you voltage drop resistor.
 
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jamie.91

jamie.91

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I don't have a clue how to do the above, but I planning finding out!

Thanks for the reply
Jamie
 
StefanFS

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Hello Jamie91!

A simple AMC7135 driver from a number of suppliers on several continents that drive one Cree XM-L emitter. Using three C NiMh cells will work wonderfully in a 2D host. Need to remove the anodising in the tailcap and cut the spring so it fits in the recess. Also something to make a tube to support the cells in the body. I have found that 1.4-2A is an ideal compromise between runtime and output.

Stefan
 
jamie.91

jamie.91

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Thanks for the reply! Could you pm me a link to somewhere that sells the please

I'm a little confused about driver and cell set up, especially with the double piggy back circuit things lol

Thanks Jamie
 
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shdwkeeper

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Wow, can't believe I wrote this "How To" almost 3yrs ago.

Hopefully this helped a lot of folks out :)

Thanks to everyone for all the feedback and positive comments.
 

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