Help with 2d maglite battery choice and wiring

ledlou

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Oct 17, 2010
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Hi everyone,

I have tons of experience with custom led builds(mainly reef tanks), but no experience with modding flashlights. I have an old 2d maglite laying around and Im going to try and mod it for an led. I plan to use 1 xml and a 7135 style driver. I know this is a basic build that has been covered many times, but im struggling with battery choices and wiring. I have basically narrowed it down to running either 4 - 14500 with 2aa holders wired in parallel, 2 - 18500/26650/32650 wired in parallel. Given the better availability of quality brands I think the 2-26650 option is what im leaning towards. What I cant figure out is how you guys are running 2 - 26650 in a maglite 2d and wiring them in parallel? I understand I would need to use a pvc pipe or something like that to make up for the smaller battery diameter, but how do I run them in parallel to maintain a 3.7 input voltage?

Im open to other battery suggestions or wiring options so if you know of a better route to go please let me know.

Thank You
 

jonwkng

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Jun 12, 2013
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Hi ledlou,

It is common practice to run 2x Li-Ions in series (Commonly 32650s or 26650s with sleeves, as you've mentioned). Put simply, the driver handles the difference between what the batteries supply and what the emitter needs. Find the correct constant-current driver with the appropriate operational voltage range that you need. The stock MagLite switch should be bypassed or modded in all instances (A must if you're planning to use >2 Li-Ions).

Have fun!
 

fivemega

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Jan 28, 2003
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In order to maintain 3.7 volt using pair of 26650, You will need to separate them from terminal contacts then wire them in parallel.
This might be complicated for beginer but not for you. Also time consuming to remove and recharge.
Second choice is to use custom made 2 parallel 18650 host.
Another possibility is to use 3 low self discharge NiMH "C" cells.
 
Last edited:

ledlou

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Oct 17, 2010
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So it sounds like I have 2 options to make this work.

1.
Hi ledlou,

It is common practice to run 2x Li-Ions in series (Commonly 32650s or 26650s with sleeves, as you've mentioned). Put simply, the driver handles the difference between what the batteries supply and what the emitter needs. Find the correct constant-current driver with the appropriate operational voltage range that you need. The stock MagLite switch should be bypassed or modded in all instances (A must if you're planning to use >2 Li-Ions).

Have fun!

I didnt realize they made flash light drivers that accept a higher input voltage. I was able to find this driver from fast tech http://www.fasttech.com/products/16...-lithium-2-group-3-5-mode-2-8a-led-flashlight . It appears as if it is almost exactly what im looking for, although I wish the mid output was 30% instead of 50%. Do you recommend a different driver or that I order from somewhere else?

2.
In order to maintain 3.7 volt using pair of 26650, You will need to separate them from terminal contacts then wire them in parallel.
This might be complicated for beginer but not for you. Also time consuming to remove and recharge.
Second choice is to use custom made 2 parallel 18650 host.
Another possibility is to use 3 low self discharge NiMH "C" cells.

This is the route I thought I would have to go. I have some ideas as to how i could make an adapter tube that wires the batteries in parallel, but I wish I could see how others have been doing this. Do you happen to have any pictures or links to how this is normally done?



Is there any advantages or disadvantages between options 1 and 2? My only concern is if the 8.4v input driver simply burns off the extra voltage to adjust the voltage down to the 3v range for the led? If thats the case i would be better off running the batteries in parallel to conserve efficiency and minimize heat from the driver.
 

jonwkng

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I'm not the authority on drivers and efficiency, but you might want to read this excellent thread by HKJ summarizing the various options for drivers :-
http://www.candlepowerforums.com/vb...ds-are-adapted-for-different-battery-voltages

You're pretty right in terms of buck driver options and their inherent efficiency compromises, but like FM said... Taking the road less travelled may appeal to you.

There are many ways to cook a potato. :)
 

Conte

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Dec 15, 2009
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Canada
That's a good driver, I have one.
Actually, I have the 3a version from int outdoor.

It has a 30% mode.
At med it only pulls like 300 - 400 mah from the batteries.


Use 2x 26650 cells in series with that driver.

KD has a reflector assembly that can be fitted into the mag head if you have access to a lathe, or a file and a lot of patience.
 

Old-Lumens

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Nov 2, 2011
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The choice of batteries really has to be up to you. There are pros and cons of both serial and parallel. In a Maglite, the simplest way would be to either run 3 lsd NiMhs in series and use a linear driver, or to use 2x18650 or 2x26650 in series and use a buck driver, that drops the voltage down to what you need. There are drivers for what you want, if you go with 2xLi-ion, then there are several choices for that. You might try this thread. http://www.candlepowerforums.com/vb/showthread.php?188227-Driver-board-list-regulator-board-list


There are other threads and probably other drivers, but I'm not up on everything here, as I probably should be. Parallel holders for 18650 Li-ions in a Mag 2D are a royal pain. I've done them sucessfully, but I would rather just use the proper driver.
 
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