SRT7 CR123 vs RCR123 vs 18650 pro and con?

As title, what are the pro and con using these battery configuration?

eurypylus said:

As title, what are the pro and con using these battery configuration?

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CR123 is going to be the most costly to operate as quality batteries are $2.50 each. The light may be slightly brighter than if using an 18650 due to the increased voltage (two batteries at 3.0 volts each). Only available in button topped, which the Nitecore lights require.

RCR123 will be the brightest with requiring two 3.7 volt batteries feeding the led. RCR123 is down on capacity with an average of 700 mah per cell. Need to check cell length as some batteries are too long when stacked. Also need to verify the presence of the button top.

The 18650 will have the longest run time with batteries available in the 3400-3600 mah rating. Again, button tops only in Nitecore lights. Length isn't a problem with a single cell light unlike stacking one on top of another. Batteries available in both protected and unprotected flavors.

NoNotAgain said:

CR123 is going to be the most costly to operate as quality batteries are $2.50 each. The light may be slightly brighter than if using an 18650 due to the increased voltage (two batteries at 3.0 volts each). Only available in button topped, which the Nitecore lights require.

RCR123 will be the brightest with requiring two 3.7 volt batteries feeding the led. RCR123 is down on capacity with an average of 700 mah per cell. Need to check cell length as some batteries are too long when stacked. Also need to verify the presence of the button top.

The 18650 will have the longest run time with batteries available in the 3400-3600 mah rating. Again, button tops only in Nitecore lights. Length isn't a problem with a single cell light unlike stacking one on top of another. Batteries available in both protected and unprotected flavors.

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Thanks very much for the info!

Hmmmm, I was thinking the amps made the light brighter, not the volts. Would an unprotected, high-drain 18650 that could continuously pump 10-15 amps be potentially brighter?

MAD777 said:

Hmmmm, I was thinking the amps made the light brighter, not the volts. Would an unprotected, high-drain 18650 that could continuously pump 10-15 amps be potentially brighter?

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Think of volts as potential for amps; you can't have amps without volts. A cell which can sustain a higher voltage under load will push more amps through that load.

There's a good chance that an unprotected, high-drain 18650 will sustain a higher voltage than a protected, low-drain 18650, because there won't be a voltage drop across the protection circuit. In addition, the construction techniques used in a high-drain cell tend to reduce internal resistance, which reduces the voltage drop that occurs across that internal resistance. Unfortunately, those same construction techniques often incur tradeoffs that reduce the cell's total storage capacity; nothing comes for free.

There are no hard and fast rules, however. A high-quality protected cell can still do better than a mediocre unprotected cell, for example.

Also bear in mind that if the light's driver is operating in full regulation, cell voltage and drain capability are less important, because the driver will be locking the light's output to a set number of lumens anyway. As long as the cell's output stays within range of what the driver needs to maintain full regulation for as long as you want it to, that does the job.

Cell voltage and drain capability only become crucial parameters when the light drops out of full regulation and at least some degree of direct drive starts to kick in. At that point, cells which can hold higher voltages and currents will allow the light to sustain correspondingly higher outputs, although that will normally be at the price of reduced runtime.

This post is starting to sound like something from a "Flashlight Electronics" thread

On that note, I commend HKJ's cell comparators to you. He has four of them, grouped in classes of cell size and type, so that you can get graphs of how different cells compare to each other under load. Look for "Index to comparators:" at the top of this page:

http://www.lygte-info.dk/info/indexBatteriesAndChargers UK.html

Go to the reviews section of the forum and read Selfbuilts review of the SRT7 it is very revealing. On an 18650, any 18650, the SRT7 is only good for 780 OTF lumens. 2xCR123 cells gets you I think it was 830 OTF and 2x16340 nets you 840 OTF lumens. It is the same case for the SRT6. I suggest NOT using CR123 primaries because the low voltage sensor in both the Srt7 and 6 read two fresh 3 volt CR123's as just 3 volts instead of the 6 volts that the cells are actually providing. This results in the red low voltage LED in the head of both lights to flash as fast as it can as the voltage sensors in both lights only read 3 volts. An enormous and inexcusable design flaw. Now two 16340's fully charged are 4.20v just like an 18650 so that issue does not present itself with 16340's. In both my SRT6 and 7 the visual difference to my eyes is very clear in terms of output and especially definition of beam profile. BUT...16340's run out of charge fast. I use Keeppower 700mah 16340's in both my 6 and 7. No negative results from using two 16340's either both lights still work as well as the day I got them. I prefer the SRT6 as the colored secondary LEDs in the 7 are useless. I am totally convinced both the SRT6 and 7 use the exact same driver save for the extra wiring for the 7's secondary LEDs. Both the 6 and 7 actually have the same output just different size reflectors.

But to answer your question in order to get the longest run times out of your SRT7 the NCR18650GA 10 amp 18650 cannot be beat. But...if you want the highest output possible from the light then 2x16340 gets you about 60 more lumens OTF but dont have much run time.

CelticCross74 said:

But to answer your question in order to get the longest run times out of your SRT7 the NCR18650GA 10 amp 18650 cannot be beat. But...if you want the highest output possible from the light then 2x16340 gets you about 60 more lumens OTF but dont have much run time.

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Even better than 2x16340: 2x18350. Most 18650 lights can't handle the couple mm extra length, but my SRT-7 is one of the few that does. (Others: ThruNite Scorpion v2, Nitecore P12GT)

18350 have more capacity than 16340, and fully use the volume of the battery compartment, no rattles. And yes it's brighter – not a huge amount, but noticeably brighter. I use Efest purple flat-top IMRs, which are capable of more current than the flashlight is.

But bottom line, CC's right: you trade slightly more impressive output for reduced runtime. You need to evaluate your needs and priorities, and determine which you value more.

to my eyes it is not just slightly more impressive output its more output, more throw and a more defined beam profile with brighter spill. I still run my SRT6 and 7 on 2xKeeppower 16340's(you will get the same result using 2x16340 on the 6 as well). That being said I have some button top IMR 18350s on the way. They will fit I know that now and give me better run time. GA's are indeed the best 18650's you can possibly put in the lights. They dont take flat tops so protected.

I also have found a lot of single 18650 lights that have a wide voltage input driver will only give max output with two 16340,s or 18350,s.
Obviously a sanyo 3500 ga cell with a small button top is best for run time with the srt7.
I like to run 2 x imr 18350,s in my olight m2x, not only is it brighter [approx 15%] but the most important thing it will still have the same lux intensity after say 4 x 2 min turbo blasts and almost equal intensity until cells are about 3.5v and ready for changing.
With the a single 18650 high drain, on the fourth turbo run it has already lost 20% of is lower starting output starting output and going south on every turbo blast.For me, i like full power and repeatable intensity throw at the expense of run time.

got my red button top IMR Efest 18350's and put them in my 6 and 7. My 6 is the brightest it has ever been now. It is brighter than the 7 now. More throw as well. Usually 16340's do not last long in the 6 and 7 but these red 800mah Efest IMR cells are cranking away like crazy still. My SRT6 is now literally almost twice as bright as it is on a normal protected 18650. As for my Javelots I stick with long running GA's as whenever I use them I am out and about and want the most run time in those situations. Looking forward to new SRT models from the new look NC that is now actually making far better lights than they were 3 years ago and these lights meet or beat specs now. Love to see an XHP35 SRT7 and an XP-L HD SRT6 etc.

have now stepped up to AW red 800mah IMR 18350's. Far longer run times on top of the output bump.