3.0V RCR123A USB Li-ion - what are they good for?

vicv

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Hey. Take with a grain of salt as I have not used these cells or tested them. But if they are in fact regulated to 3.0v each, then regardless of the load, they will put out 3.0v. So 6.0v total. Fivemega tested them with a p60 and got 5.8v. So pretty close and could be an error somewhere. I do not believe the tail cap switch adds 0.8 v of resistance. He assumed that but that assumption is wrong in my opinion. I've never seen anything to suggest a switch adds anywhere close to that. So that means you're feeding a lamp designed for 5 volts, 6 volts. That's a big jump. In my opinion you will be accelerating the wear of your lamps by quite a bit with these cells. Something like a p91 is designed to run on 6.6v. Running on 2 regular lithium ions will give approx 7.4-7.6v freshly charged. And last one I did that with only lasted a couple hours of use. So it's the same amount of overdrive.
If wanting to run rechargeable cells, your safest bet is to run a 3 cell lamp. Like a p90 or a lumens factory sr9. Or check out kaidomain for one of their 7.4/9v lamps. They're like $3 each and excellent. And use two normal 16340. Or better yet, a kadomain 3.7v lamp and a 16650. These are a bit brighter than a p60 and are cheap and great
 
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ViperaPiper

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I have to agree they run a P60 way too hard. Before vicv warned me I was really impressed how bright and how white the beam was :D. Considering that I rarely use it for more than a minute and more for the experience than actual need I guess primaries are justifiable.
As for the RCR123As, currently I am rotating them between my Kroma, U2, and KX4, and they seem to be doing fine. They have quite an abrupt power cut off though.
 

aznsx

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They have quite an abrupt power cut off though.
There are several reasons why I'm not currently using cells of this type, but this is probably the primary reason. The chances of my light instantly going 'dead' in my hand while needing to use it, barring a component failure, is a condition I don't want to increase the odds of. To the contrary, I want to minimize those odds. That's why I will continue to use LFP123 cells (in applications which allow it) in LED lights instead of these. For other applications, I would perhaps consider using them.
 

vicv

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There are several reasons why I'm not currently using cells of this type, but this is probably the primary reason. The chances of my light instantly going 'dead' in my hand while needing to use it, barring a component failure, is a condition I don't want to increase the odds of. To the contrary, I want to minimize those odds. That's why I will continue to use LFP123 cells (in applications which allow it) in LED lights instead of these. For other applications, I would perhaps consider using them.
Well that's not the chemistry but the fact these are protected. Not protected 3.7v 16340s won't abruptly cut off. I agree though I like lfp as well. But they would probably instaflash a p60 with the extra 0.6V
 

aznsx

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Well that's not the chemistry but the fact these are protected. Not protected 3.7v 16340s won't abruptly cut off. I agree though I like lfp as well. But they would probably instaflash a p60 with the extra 0.6V

Agreed it's not just the chemistry. It's the fact that these are a completely different animal because they contain a switching power supply and are also based on a chemistry which, unlike LFP, is highly sensitive to over-discharge which imposes such limitations. XTAR is on the right track by starting to provide some form of mitigation to this 'sudden death' characteristic in their latest AA implementation of this technology. While LFP voltage is nearly flat through most of the discharge cycle, their chemistry does inherently provide some dropoff prior to shutdown, and in the lights I use them in is sufficient to mitigate the 'sudden darkness' issue in practice. So, it is also partially / indirectly a function of chemistry as well. This is not just about "protection" circuits (in the classic sense), although I know that is a subject that is near and dear to your heart:)
 
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