What are you toting today?

cyberhobo

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Oct 23, 2005
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533
Location
Highlands
Emisar D1 FC-40 R9050 5000K

20231120_064945.jpeg
 

ViperaPiper

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Apr 17, 2019
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34
Nice light. Just know that p60 won't last long on the two 3.0v rcrs
Thanks! But why is that? Isn't the voltage regulated to 3.0 volts like on the primaries? I know the bulb is supposed to be a 5 volt one and driven at 6 but why would the rechargeables have a different effect?
 

vicv

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Joined
Mar 22, 2013
Messages
2,730
Location
Southern Ontario
Thanks! But why is that? Isn't the voltage regulated to 3.0 volts like on the primaries? I know the bulb is supposed to be a 5 volt one and driven at 6 but why would the rechargeables have a different effect?
Because primaries don't put out 3v. On a p60's 1A load, they're 2.5v a cell. So your 5 volts. The regulated lithium ion will be 3v under load. So 6v total. So you're overdriving by about 20%. Which is quite a lot for an already hard driven bulb
I can't say for sure how bad it'll be, but another member here claimed about an hour of use before their brand new p60 popped
 

ViperaPiper

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Apr 17, 2019
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Keeppower 3v are 1000mah each

CR123 Primary are around 1600mah ea
Because primaries don't put out 3v. On a p60's 1A load, they're 2.5v a cell. So your 5 volts. The regulated lithium ion will be 3v under load. So 6v total. So you're overdriving by about 20%. Which is quite a lot for an already hard driven bulb
I can't say for sure how bad it'll be, but another member here claimed about an hour of use before their brand new p60 popped
I really didn't know that about primaries. Always thought that because they were lithium they had a pretty stable voltage maintaining. And I was wondering why it is so bright! But what reduction in lifetime are we talking here?
 

vicv

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Joined
Mar 22, 2013
Messages
2,730
Location
Southern Ontario
Lithiums don't really have a stable voltage on discharge. Lifepo4 does. But lithium ion gradually decreases as they drain. So do lithium primary cells. Here is a normal 16340
IMG_0130.png

Here is a graph for a primary. Look at the purple line. That's 1.0a. It also steadily falls

IMG_0131.png

As far as how long it'll last, it could pop at any time. There's not really a way to know

Both graphs were taken from www.lygte.com hosted by HJK
 
Last edited:

bigburly912

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Joined
Aug 12, 2015
Messages
3,361
Location
Virginia
I really didn't know that about primaries. Always thought that because they were lithium they had a pretty stable voltage maintaining. And I was wondering why it is so bright! But what reduction in lifetime are we talking here?
Last time I tried it I got about 20 minutes on a pretty hard core use firefly hunt with my 7 year old haha.
 

ViperaPiper

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Joined
Apr 17, 2019
Messages
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Lithiums don't really have a stable voltage on discharge. Lifepo4 does. But lithium ion gradually decreases as they drain. So do lithium primary cells. Here is a normal 16340View attachment 52741
Here is a graph for a primary. Look at the purple line. That's 1.0a. It also steadily falls

View attachment 52742
As far as how long it'll last, it could pop at any time. There's not really a way to know

Both graphs were taken from www.lygte.com hosted by HJK
That's a shame. Is it better to underdrive it with a 16650 then? There's no way I am running primaries even though I am almost never keeping it on for more than a few minutes.
 

vicv

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Mar 22, 2013
Messages
2,730
Location
Southern Ontario
If you were only using it at a few minutes at a time set of primaries will last a while. Do you have a way to get them cheap I would just use those. That bulb is meant to run two primaries. On a single 16650, You will probably be at around 20 lumens, and it will be quite orange. P61 will be a little bit better though. That's a 4.4v bulb so will not be underdriven as much. My recommendation is this. http://kaidomain.com/3_7V-12W-or-15W-Xenon-Bulb-Drop-in-26_5mm.
It draws 1.8A on a single cell. Very white and bright. And lasts 10s of hours. For the price they're incredible
 

ViperaPiper

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Joined
Apr 17, 2019
Messages
34
If you were only using it at a few minutes at a time set of primaries will last a while. Do you have a way to get them cheap I would just use those. That bulb is meant to run two primaries. On a single 16650, You will probably be at around 20 lumens, and it will be quite orange. P61 will be a little bit better though. That's a 4.4v bulb so will not be underdriven as much. My recommendation is this. http://kaidomain.com/3_7V-12W-or-15W-Xenon-Bulb-Drop-in-26_5mm.
It draws 1.8A on a single cell. Very white and bright. And lasts 10s of hours. For the price they're incredible
Thanks for the knowledge! I have a few other Surefires so it definitely is a very valuable piece of advice. Especially considering that these older flashlights are like classic cars which are no longer officially supported but you run anyway for that special experience.
 

Megalamuffin

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Jan 18, 2021
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Oklahoma
Because primaries don't put out 3v. On a p60's 1A load, they're 2.5v a cell. So your 5 volts. The regulated lithium ion will be 3v under load. So 6v total. So you're overdriving by about 20%. Which is quite a lot for an already hard driven bulb
I can't say for sure how bad it'll be, but another member here claimed about an hour of use before their brand new p60 popped

I only got a few hours out of a new p60 that I used with two 3v rcr123's.
 
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