Trustfire TR-J12 measurements (5 x XM-L)

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VIET PRIDE BULLIES
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Thanks Benckie, It's hard to pick between them sice they not much differences .
Shopbot
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drd wrote:

I hope you guys didn't miss the point of my post.  My J12 is discernibly brighter with four NiMH C cells than with two 18650s.

Based on Mitro's excellent data, and 2100's assertion that 2 Li cells were brighter than 3, I hypothesized that a voltage of around 6.5-7.5 might be ideal.  That means 2 undercharged Li cells, or perhaps 6 NiMH sub-Cs.  I could not find sub-Cs that would give a desirable enough run time or fit more than 5 in the tube, so I tried some old rechargeable C's I had laying around.  It worked great!  Mitro's graph is missing data in the relevant range of my experiment, so I did a linear regression based on the other data points and it makes perfect sense now.  You're still getting more watts with 4 NiMH C cells than you are with 1, 2 or 3 Li cells.  Significantly more watts than 1 Li cell, and moderately more than 2 or 3.  Plus 21.6 wH instead of 19.2 (so about 12.3% longer run-time) and no worry about ruining or popping your unprotected Li cells. 

 

Woah. That is news here. I am shocked! I will give it a go tomorrow. See how it is with a naked eye since I don't have a lux meter.

drd
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I've been migrating back to NiMH cells lately.  They're just so versatile and forgiving.  My infatuation with Lithium is starting to cool down since 2 of my brand new 26650's started leaking for no apparent reason.   That's what got me rethinking older chemistry whenever possible.  Especially now that the USPS has turned on Li, it's probably time to buy Lithium stocks and NiMH cells.

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Shopbot wrote:

drd wrote:

I hope you guys didn't miss the point of my post.  My J12 is discernibly brighter with four NiMH C cells than with two 18650s.

Based on Mitro's excellent data, and 2100's assertion that 2 Li cells were brighter than 3, I hypothesized that a voltage of around 6.5-7.5 might be ideal.  That means 2 undercharged Li cells, or perhaps 6 NiMH sub-Cs.  I could not find sub-Cs that would give a desirable enough run time or fit more than 5 in the tube, so I tried some old rechargeable C's I had laying around.  It worked great!  Mitro's graph is missing data in the relevant range of my experiment, so I did a linear regression based on the other data points and it makes perfect sense now.  You're still getting more watts with 4 NiMH C cells than you are with 1, 2 or 3 Li cells.  Significantly more watts than 1 Li cell, and moderately more than 2 or 3.  Plus 21.6 wH instead of 19.2 (so about 12.3% longer run-time) and no worry about ruining or popping your unprotected Li cells. 

 

Woah. That is news here. I am shocked! I will give it a go tomorrow. See how it is with a naked eye since I don't have a lux meter.

I have tested drd theory on C batteries and it is brighter then 3 x 18650 configuration but not brighter then 2 x 18650 configuration using tailcap readings. My results are:

Tailcap Readings (on High mode of course!):

2 x 18650 (4.14v/ea) = 4.5A - 5.5A
3 x 18650 (4.14v/ea) = 2.33A
4 x C (1.55v/ea) = 2.50A - 2.75A
4 x AA (1.4v/ea) = 1.8A

drd
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Shop,

If you have a luxmeter then please test the values to validate your tailcap readings (if you don't mind and have the time.)  I just did a dark room bounce using 2 ICR 18650s (BDL, 1.3aH) and got a stabilized reading of 293 subtracting the ambient background.  These ICRs are good cells that give you the max and I use them with my incandescent lights.  Using 4 Accupower C cells I just got 293 also.  The ICR cells match output exactly with the C setup, but the TR protected cells (the flames that came with the light) I tested with first did not match output.

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Hey drd,

I do not have a luxmeter unfortunately plus those readings are from a $15 DMM. So its most likely not accurate at all.

To be honest, I can't tell the difference between all 3 configurations with the naked eye. Would be much easier if I had two flashlight and shine it side by side. 

I have also posted amateurish pics comparing the three on the other thread: http://budgetlightforum.com/node/10071

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With my Skyray 856 turning out to have a crappy driver design, I'm again in the market for a 2x26650 light.  I sure would love to know how the Trustfire J12 compares to the UniqueFire UF-S7.

Richie

drd
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Hey shop, those are actually some pretty good pics!  They look well positioned to duplicate one another accurately.

And I'm using cheap equipment as well, so my readings probably aren't any better than yours.  I got my DMM from Harbor Freight for maybe 10 bucks (if that much) and a luxmeter (LX1330B) from amazon that was about $30.  It's not fancy, but supposed to be reasonably reliable as far as the cheaper models are concerned. 

It just surprised me how well the Cs worked.  Duracell would most likely be the best alkaline for this purpose, just like you used.

 

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Yeah, the C's are pretty good. But I'll still be using my 18650's since I don't have any rechargable Cs.

Pretty good flashlight. It works with many types of batteries. 18650, 26650, AA, C. Anymore? lol.

drd
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Richie086 wrote:

With my Skyray 856 turning out to have a crappy driver design, I'm again in the market for a 2x26650 light.  I sure would love to know how the Trustfire J12 compares to the UniqueFire UF-S7.

I'm not sure about that UniqueFire, but I think I've seen a thread or two about the UF-S7 on this board.  It's quite intriguing indeed!  But for an general purpose flashlight, it's hard to beat that J12.  It's bright enough for just about anything in high mode, has a good run time, med/low modes too, not too bulky, versatile battery options, affordable, feels durable and comfortable to grip and use practically, etc..  I imagine that 7 xml U2 would just be that much brighter with a slightly cooler tint, with maybe a bit less throw but greater spill, otherwise it looks almost identical to the J12 in design.

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