My first Maglite Modding Attempt - Require help on a driver

[Pummy]

Hi

So I have two 3D maglites at home, one with a std bulb and the other with a Terralux 2/3D dropin.

I have ordered...

1 *MCE (DX)
3 * Q5 WC tint
Some Thermal Epoxy
GITD Power (Just for fun)

But am stuck on driver considerations.

My power requirements for this is one of...

2.7V (3 * depleted NiMH) to Alkaline unloaded voltage of 4.5v I do not know about how sag affects the voltage under load. The options I have are...

3 D size Duracells (Since I have the old unused cells to use up)
3 8000mAh LSD Cells from Maplins (UK store)
3*AA to D parallel using Lithium primaries when I am stuck in a pinch or using some high cap NiMH's instead. Figure that 3*AA is much better and easier to use for my other AA Q5 EDC if I want to use up the cells. Also since 4 LSD's come in a few bob cheaper and can be used in my daughter's electronic toys around the house, I can at least justify the expense to her indoors.

I was looking originally at the AMC 7135 chips in parallel however I have not found a guide here on how to assemble them and if the voltages I am trying to work with would be suitable. For the most part, I figured NiMH with a resistor would be good enough since a 2A load should bring the voltage down close to Vf of the MCE and the flattish discharge characteristics of the NiMH would allow me to have a relatively flat output.

Whilst I am running a Li-ion on my EDC, I would like to avoid this since the other torch may be used by my wife, or if I can get the parts together quickly enough and assembled they will be sent along with my family members onto their trip to India (Thread asking for ones to take advice is here...

http://www.candlepowerforums.com/vb/showthread.php?t=241743

Whilst it would be nice to have a fully regulated driver, I have not been able to read or absorb enough information to be able to make the choices I need on my own.

As for the uses of each torch, one will be lying in a car to be used on the odd occassion however the other will be getting a lot of use.

If you guys can give me any pointers on threads to read or your own experiences with what I have, I would be most grateful.

I have no qualms about reading up some guides or even giving me the search terms to search for in the CPF Google search, just that I have tried some terms I thought my be appropriate and they have bought up stuff which is a little over my head when the stuff gets interesting.

Thanks in advance everyone.

 

[jar3ds]

read the spec sheet on the 7135... your 4.5v setup would work great w/ the NiMH cells... you just don't wanna push the 7135's past 5v

 

[Pummy]

The other point here is that I intend to run the MCE as a 4s (think that is the right vernacular to run all 4 in parallel). I went for MCE as opposed to P7 since the Vf is more than likely to be lower (Assuming a good P7 is higher than the worst MCE).

I will search for 7135 guides on how to assemble them for driving the MCE.

Can I also assume I can run the 7135's in a single mode o are there mods for a low numbered multi mode fashion?

 

[Hack On Wheels]

The other point here is that I intend to run the MCE as a 4s (think that is the right vernacular to run all 4 in parallel). I went for MCE as opposed to P7 since the Vf is more than likely to be lower (Assuming a good P7 is higher than the worst MCE).

I will search for 7135 guides on how to assemble them for driving the MCE.

Can I also assume I can run the 7135's in a single mode o are there mods for a low numbered multi mode fashion?

-s indicates series and -p indicate parallel.

I think LITEmania (on cpfmarketplace) might have driver boards that will run a parallel wired MC-E close to full spec, that might save you some fussing.

Shiningbeam also has a good looking 3-mode 2.5A driver... but he is out of stock currently.

 

[jar3ds]

driving the MC-E in series ~13.6v @ 700mA can be done w/ the maxFlex as long as Vin is enough to limit input current to 2.5Amps

 

[Pummy]

This was completed on Friday night but elected for DD with alkalines as my first attempt until I read up and understand what I need to do for a driver based solution to drive the LED at the correct current, possibly overdrive as well.

I got thinking about running a 4 cell combination in the 3D host and wondered if there was a driver that could cope with these scenarios...

4 of AA to C convertor with Alkalines (6v sagging to maybe 4V?)
4 of AA to C convertor with NiMH (sagging to 4.4V maybe?)
4 C size LSD NiMH (4.4V maybe under draw?)

As well as these combinations...

3 Alkalines (5% variance MM shows voltage @ 3V so only pulling 200mAh / 250mAh per die, based on 800mAh - 1A draw at tailcap)
3 D size LSD NiMH (3.3V under high draw I believe)

I figure that I could run the 3*7135 in a stack and run at 3.15A (with H22A heatsink). I understand that runtime would be low. I read somewhere that the 7135 requires 0.4V above Vf to remain in regulation. which puts the 4 cell combinations into play here over the 3 cell setup. 4 cell also works for me as I can then buy cells / chargers based on 4 cells per charger, then run either single cells or in a 4S2P configuration to reduce the current draw per cell.

I am thinking a 4 cell setup is much better to drive for, buy primaries for, and reduces the current draw if I can find a good buck solution for this setup.

What I would like to know about is if the 7135 driver board advice or if I should look at some other buck drivers if my Vf + 0.4V falls within the sagged voltage range @ 2.8 - 3.15A current draw.

Another option that would be VERY useful is if I can remove one board and add a multi mode board so that I can have a PWM output controlling the primary drivers somehow.

I read some threads on here about one 1400mAh board with modes and a 7135, however I am looking for an efficient as possible solution. I will be looking for threads that may be suitable, however if anyone has some experience or constructive advice, I would be most grateful. Having fun with this over my previous big hitter (UF A10 on 14500) but still would like to be able to have something with modes that does not have any parasitic drain so that I can leave it in the house as an emergency light with maglite diplomacy. I have been reading about the TK40 and got the idea about 4 cells after reading that. I will be getting one, eventually, however I have not figured out how to siphon the money away from the accountant of the house (wife) to pay for it

 

[Justin Case]

Don't expect anything close to full power output using 3 or 4xAA alkalines when driving your 4P MC-E. Search CPF for "alkaline shootout" and you will see that AA alkalines suffer severe voltage sag even at 1A. A 4P MC-E at full power needs 2.8A. It's not going to happen. AA alkalines probably can hold out for a few minutes at 1A, which is full power for the Cree Q5 (I assume an XR-E). A driver can do only so much if you use alkalines. The power source still has to be able to meet the voltage requirements that the driver needs to run in regulation.

AA Eneloops probably can deliver the voltage and amps. Search CPF for "nimh shootout".

Good quality C or D NiMH cells should also be able to deliver the volts and amps. The question then becomes what driver will work best.

If you use AMC7135-based drivers, you need enough voltage to stay above Vf + the dropout voltage, which is 0.120V, to run in full regulation. Check the shootout data to see what voltage various cells can hold under the relevant load (i.e., 1A or ~3A). If you have a 3D Mag, I'd probably stick with 3xD NiMH instead of messing around with all of these other lesser combinations. If you need to use alkalines in a pinch, they will work, but at reduced performance vs NiMH. IMO, you are wasting your time trying to optimize performance for alkalines. Optimize for NiMH and take what you can get with alkalines, especially if they are a secondary battery configuration, most likely to be used in a pinch or just to use up some extra cells laying around. 3xD NiMH should work great running a 4P MC-E or a Cree XR-E Q5 at full power using an AMC7135-based driver.

If you choose a buck driver, then you need to check the specs to see what its voltage overhead is to run in full regulation. That will dictate what your battery configuration ought to be to reach that required voltage. I think you will have a hard time finding a 3A buck driver that will run in regulation at 3xNiMH voltages. You probably can find something for 4xNiMH (e.g., 3xSOB1000, which is going to be expensive, or perhaps 3xKD1640, which is a lot less expensive). If you run 4xC in your 3D Mag, that could work. If you bought one of those D to 3AA cell holders, that could also work (you'd have 9AA, or over 10V nominal).

If you use one of those 3AA holders and get 10V or more, then the Shark Buck or hipCC are excellent buck driver choices. I'd still use NiMH AAs, but alkalines will work better now that the input voltage is much higher.

"Low voltage" applications are difficult for buck drivers and 3xalkaline or 3xNiMH is low voltage. For those battery configurations, IMO your best bet is to go with an AMC7135-based driver. There are plenty of threads on wiring these boards in parallel to get single mode, 2.8A operation or multimode 2.8A operation. For example, search CPF for "stefanfs maglite".