[noob] Tri-Emitter Mag Mod - and some math questions!

[Ducaticorse]

(Apologies in advance if I'm asking too much of a "use the search function" question, I tried to do as much homework on this as I could)

Hi! Very much a mod/builder newbie here, but I do have some other electronics experience and some mild fabrication skills. I think one of the multi-emitter Mag modifications would be a really fun project, so here's what I'm considering building up. Reason for my post is to seek some sense-check on the package before getting started on gathering up the various components.

Host: 2C or 2D Mag - mod stock switch to momentary
Emitters: 3 x SSC P4
Driver: TaskLED MaxFlex @ 1A
Power: 2 x AW 18650 or 2 x AW LiIon C-Cells

Goal: Lots of light in a reasonably-sized package w/variable power capability

If I understand George's guidelines correctly, I am calculating:

Output Power: 3 * 3.7V * 1A = 11.1W
Input Power: 11.1W @ 88% efficiency = 12.62W

Min Input Current: 12.62W / 8.2V = 1.54A
Max Input Current: 12.62W / 6.0V* = 2.10A
*Assumes setting the voltage cutoff @ 3V/cell

This seems like a pretty "typical" or basic setup from what I've seen (if typical can be applied in the Homemade/Mod section, heh!) and within the guidelines of the driver, cells, and emitters.

My questions:
1. Does this sound like a decent plan? Any suggestions/corrections/ideas?
2. Is the MaxFlex a good choice for this type of build? Alternatives?
3. If I wanted to estimate runtime @ ~1A, does this calculation using "rated" battery values get me in the ballpark?

2200mAh (18650):
2.2Ah / (12.62W / 7.4V) = 1.29 hours

3300mAh (C-LiIon):
3.3Ah / (12.62W / 7.4V) = 1.93 hours

Thanks for any guidance from the more experienced folks here. I'm looking forward to a fun project. I have a friend who is a toolmaker, so if the project comes out as hoped, maybe I'll have him flute/fin the head and/or battery tube of the host like so many of the great projects I've seen here.

 

[VidPro]

hey welcome to the forum!

you can do ALL my math too

1. Does this sound like a decent plan? Any suggestions/corrections/ideas?
yes it sounds better than mine, cause i am attermpting single D li-ion, and the voltage input isnt going to be as well liked.

2. Is the MaxFlex a good choice for this type of build? Alternatives?
from what i can find its a good choice, unless you want more parts and pieces

3. If I wanted to estimate runtime @ ~1A, does this calculation using "rated" battery values get me in the ballpark?

with that cell type (li-ion) its very close, some of the cheaper li-ions dont have that kinda capacity under load, but your math is better than mine , id take off 10% of your minutes for reality. a awesome LG cell of 2400ma say will do 2200 at the drained in an hour rate.

also i would have to mention that even though the curcuit will cutoff, you still want protection on the cells, but i figure you know that , cause of all the rest of the stuff you have covered to a T.

------------------------

you will be required to post pictures so please take them when you build it. i want to see how you do the maxflex specially.
what kinda reflector/optics item were you going to use?

 

[Ducaticorse]

hey welcome to the forum!
<snip>
you will be required to post pictures so please take them when you build it. i want to see how you do the maxflex specially.
what kinda reflector/optics item were you going to use?

VidPro - Thanks for the welcome and the comments. I realize that there are several other similar posts here regarding the same type of question, so I really hesitated whether to post on my questions or not. I figured I at least tried to cover all the pertinent points (driving current, power source, etc), so not as to come across as one of the "I'm not patient enough to search" types.

I will indeed post some pics when the project is complete, although that may be a while since I've only just started gathering up the components. The only light of this type that I will have to compare with is a bicycle-specific tri-SSC built by some folks in New Zealand called Nightlightning. If I can put together a handheld mag-based flashlight that provides the kind of output (lumens) that my Nightlightning iBlaast does, I will be thrilled, to be quite honest.

If the Mag project works out as I hope it will, I am considering making a mag-head based bicycle tri-emitter like some others I've seen around. It would be a nice compliment in the school of "significant overkill" (if there is such a thing) to go along with my iBlaast.

I do plan to power the tri-SSC Mag with protected cells. I already have some spare 18650's and am considering AW's C-LiIon cells as another alternative for more runtime. To be honest, a single-Seoul Mag is plenty for most of my handheld lighting needs, I just thought it would be a fun project and I really like the looks of the multi-emitter Mags I've seen here.

I've been looking at using the IMS20 reflectors for this project, hoping to put it all together on a reasonable budget. I need to take some measurements to make sure that there will be adequate space for this configuration, but it seems again pretty common so I'm hoping that I can learn from others work.

Again, thanks for the welcome and the feedback.

 

[ktt]

Min Input Current: 12.62W / 8.2V = 1.54A
Max Input Current: 12.62W / 6.0V* = 2.10A
........

2200mAh (18650):
2.2Ah / (12.62W / 7.4V) = 1.29 hours

3300mAh (C-LiIon):
3.3Ah / (12.62W / 7.4V) = 1.93 hours

These runtime calculations give a bit too high runtime, because you took the current from the minimum value i.e. 1.54 amps, when the maximum drained value (from your calculations) is 2.10 amps. For proper runtime calculation, we would need to know cell characteristics (discharge curve at certain wattage load), but as those are not available, I would take the mean amp amount (appx 1.82), use that in calculation and then deduct some 10% as error margin.

So, for 2200 mAh, it would be (2.2 Ah / 1.82 A) * 0.9 = 1.09 hours, and for 3300 mAh about 1.63 hours.

But anyway in the same ballpark

- Kalle

 

[SafetyBob]

Ducaticorse, actually, thank you for posting this. I have been overwhelmed by the choices out there and I have also been looking at the 3 LED M@g mod (although I think I am going with CREE's), the only thing that has kept me from this is the battery question.

May I ask what charger setup are or will you be using with the Li-ion's. I actually have two of FM's C sized tailcap extenders on the shelf ready for installation once I get everything built. I see there are very good regular C and D sized Li-ion solutions out there that wouldn't require all the modding and I could use them in a regular M@g with my Malkoff droppins. I would like to get your opinion on why you went the way you did.

Thanks,

Bob E.