Battery choices>>expert opinion needed.

[DR_DEUCE]

A> 1x18650, approx 2400Ma.....or
B> 2xCR123A, approx 750MA each.

To be used in a LED flashlight.

Which might be brighter...run longer....more stable over running time.
Any help appreciated!

 

[RedForest UK]

The Trustfire 2400mah rated Red and Black DX cells really are 2400 mah, but if you want more and with a higher discharge rate possible then AW's 2600mah cells are the very best, just a lot more expensive.

For RCR123's I'd go for AW every time, they may not be true 750mah but they are the closest you can get by quite a way. :thumbsup:

 

[DR_DEUCE]

Thanks for the brand info, which is helpful.
I was initially wondering which option....A or B, would be more advantageous to buy, relating to run time, brightness, stable output during runtime. Not really concerned about the cost.
Thanks....

 

[RedForest UK]

Oh yh sorry about that, I missed the 'or'

Well 18650's will provide much higher capacity, but rcr123's will provide higher voltage/ So the general rule would be 18650's give longer runtime and RCR123's a more flat output and possibility of brighter output too..

That being said it really depends on what light you are using, there are many lights now which are fully regulated on 18650's as well as rcr123's and put out the same output on both, just for a lot longer with 18650's. In that case there really is no reason not to take 18650's unless you really dont want rechargeables at all, which isnt the case for you anyway.

Could you give any pointer on what make/brand/quality of light you will be using the batteries in, then I'll be able to give much more specific and hopefully helpful advice. :thumbsup:

 

[jasonck08]

Just so you know, the highest quality RCR123's test out at 600-650mAH, and thats at a very light .2C load. When you put most RCR123's under much load like 1A, there capacity will drop a LOT. I tested an AW cell out and only got 463mAH @ 1A! 18650's are really the way to go! Much higher capacity.

 

[DR_DEUCE]

OK>> these will be used in a very CHEAP Ultrafire from DX. An $18 light.
A 501 or 502 unit.
It can run either 2 cr123's or 1 18650.
Seems the light(s) are regulated with a 1000 or 1200Ma output.
SO>>>what do you think now???????????

 

[RedForest UK]

OK>> these will be used in a very CHEAP Ultrafire from DX. An $18 light.
A 501 or 502 unit.
It can run either 2 cr123's or 1 18650.
Seems the light(s) are regulated with a 1000 or 1200Ma output.
SO>>>what do you think now???????????

In that case the cr123's may give you better regulation/output overall, but it still depends on the specific light. IMO if you are only going to spend that much on the light then theres no way youll want to shell out more than the same again for the high quality AW RCR123 cells, get yourself some 18650's for much greater capacity and longer runtime.

Pick up these: http://www.dealextreme.com/details.dx/sku.20392

And this: http://www.dealextreme.com/details.dx/sku.6105

They are by far and away the best available on DX and IMO in that entire price range.

 

[DR_DEUCE]

Red Forest.....with the cells you recommend, they are rated at 3.7v. and cutoff at 4.2 and 2.75v.
When fully charged, I assume they'll be 4.2v, so why are they called 3.7v?
Also, if the light I use says 1000Ma and has an input rating of 3.3 to 8.4v, it seems like the light will shutoff before the battery will shutoff.....am I correct.
I know I'm being anal about this, but thats how I do everything.
I eat off my engines!!

 

[VidPro]

they call the cells voltage "nominal" or (dictionary) "according to design". or "in name only" from wikidictionary "Of or relating to the presumed or approximate value, rather than the actual value."

if i renamed it, its the "working average" voltage, but it isnt that either, because at 3.6 they are pretty low. mostly it is just thier label thing, and the High and Low that you know , is more Usefull a determination of whats gonna happen.

the range will be the 4.2 - about 3.?? depending on the cell , they are pretty much depleated before that 2.75 max low spec.

the light is not likly to shut off completly . . before the battery capacity is mostly depleated.
What will occur is: when the voltage drops below the leds voltage the regulation will no longer be in play, and the light will start going down in output.
Then eventually the driver might stop operating , and basically the battery is pretty much discharged, and the output is pretty much very low too, a protection curcuit on the battery can also cut-out to stop the battery from being discharged to far, but the light generally will be very very low by then.
so
it will act sort of like you have this low reserve tank going, where you noticed that the battery certannly needs to be charged, but you can still safely discharge a bit further (helps also to have protected cell), and it will discharge slowly then because the led (at the lower voltages) wont be driven as hard.

its better to see this for real, its really nifty how you get a good full regulated output for quite a while, then dwindling output , where you know you need to recharge, but are not left in the dark.

if you must stay on the High-Side using the 2xbatteries, AND you use the 2x rechargables with only ~600ma , the 18650 will do almost everything they will do usually, plus run longer at low.
but when it is primary 2x batteries, then they have much more capacity, so with those you stay on the high side longer, and when it starts to drop in output , it is done.

 

[357mag1]

A> 1x18650, approx 2400Ma.....or
B> 2xCR123A, approx 750MA each.

To be used in a LED flashlight.

Which might be brighter...run longer....more stable over running time.
Any help appreciated!

You could do like I did and come to CPF and read about how some think all other batteries are inferior to the AW brand. Start thinking we may have some battery snobs here and buy a bunch of ****fire batteries or even the Battery Station RCR123s. Then when they start to fail after a couple of uses, drop to 4.10 shortly after being charged and don't hold their voltage well under load you will eventually migrate to AW cells. Now I won't buy anything else.

The only exception I make is the Ultrafire 18350 which seems to hold up pretty well so far and is the only battery of that size to my knowledge. If AW starts making 18350s tomorrow then I will switch.

 

[BeeMan458]

You could do like I did and come to CPF and read about how some think all other batteries are inferior to the AW brand. Start thinking we may have some battery snobs here and buy a bunch of ****fire batteries or even the Battery Station RCR123s. Then when they start to fail after a couple of uses, drop to 4.10 shortly after being charged and don't hold their voltage well under load you will eventually migrate to AW cells. Now I won't buy anything else.

I'm still having my wonders as I await this fateful day to occur. Not only have I read here but I have been web searching for days now and not found much to corroborate your above. I'm not saying it's not true, just have troubling finding ancillary, non-CPF information. All the complaints that I find seem to have auto-pointers to CPM and no complaints in other venues.



Millions and billions of batteries and little to no warnings other than watch for heat and don't overcharge or discharge faster than the battery is rated for and life will be beautiful all the time. And now, due to my readings here, oh goody, I get to do DMM readings of my charger as I'm researching out IMR rechargeables to put in my yet to be received, 5A draw, RRT-3.

:thinking:

And why are these IMR 18650's so anemic in the mAh arena? Why can't I get a protected, 3000 mAh, rechargeable, IMR 18650 button-top, in a safe, Li-ion chemistry with a 30A maximum discharge rate at a reasonable price?

:mecry:

 

[DR_DEUCE]

Relax boys.....we are getting a bit off topic.
I was asking which SIZE cell the CPF recommends.
1 18650 at 2400ma, OR 2 cr123's at 700ma.

 

[BeeMan458]

A> 1x18650, approx 2400Ma.....or
B> 2xCR123A, approx 750MA each.

To be used in a LED flashlight.

Which might be brighter...run longer....more stable over running time.
Any help appreciated!

Relax boys.....we are getting a bit off topic.

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

Your above is a valid and simple question but I find a complete answer gets a bit nerdy in reply.

In the simple, all things equal, my understanding, higher volts equal brighter, stored amperage equals how much gas is in the tank, unless volts are regulated in which to equal out the above. If regulated, then it all becomes about mAh (capacity) and how long will the emitter burn at a given output for a given amount of capacity; regulated vs unregulated. This, of course, assuming the flashlight in question accepts multiple battery styles.

After that it becomes a bit nerdy;

What's your current draw for a given flashlight application and how will you be using this light? Will you be using it to walk your dog for twenty minutes or do nighttime ops on a carrier? If stressful usage, then type of usage and battery construction comes into play; build quality and internal resistance to current flow. My opinion, once regulated, for occasional/daily, non-stressful household use, it becomes six of this and a half a dozen of the other. My opinion, if your household current draw needs are under 1.5A, you're pretty much good to go what ever door you choose to go through. If you go to the high-end throwers that are in the 1.5A or above draw range, then quality of battery build seriously comes into play. The harder you play, the better your gear needs to be. The answer to your question will depend on if the flashlight and batteries are regulated or not and how will you be using the flashlight; household (sitting on the shelf) check the basement usage vs daily, always at the ready, search and rescue needs? Another important factor, how much money do you have to throw at this money pit for as with everything, pretty much, it all boils down to available cash.

Disclosure; I'm not a flashlight battery expert and don't want to be. All I want is a battery and charger that I can forget about. But to get to this forgetful point, I have to go to "Battery U." and spend a boatload of cash to get an education on the matter. Currently, I'm sharing with you what I've picked up along the way; layperson to layperson as opposed to battery nerd to layperson.

:wave:

Hope the above helps.

:thumbsup:

 

[shark_za]

For a drop in or light that runs regulated with 3.7v then I'll take the 18650 every day and twice on Sunday.

3.7v x 2200mAh = 8140wH
7.4v x 750mAh = 5550wH

And that is at manufacturer specified capacities.
18650's do get close to that while you have a really good RCR123 if you see 600-650mAh.

 

[hoongern]

For a drop in or light that runs regulated with 3.7v then I'll take the 18650 every day and twice on Sunday.

3.7v x 2200mAh = 8140wH
7.4v x 750mAh = 5550wH

And that is at manufacturer specified capacities.
18650's do get close to that while you have a really good RCR123 if you see 600-650mAh.

Just for accuracy, it's actually 8.14Wh and 5.55Wh Note that there are also higher capacity 18650s - in the 2600mAh range, and as mentioned, RCR123s are normally actually lower than 750mAh, which means that the difference is even larger. The 18650 has MUCH more energy than 2x16340s, provided that the light you're using it with supports single 18650s.

Also, the general recommendation is that if you can use a 1 cell setup, do it. Having 1 cell reduces all the risks involved in multi-cell operation, which means that it's safer.

18650s are also very mature technology, as they are used all over the world in laptops.

------

Just as a side note (If you're not aware yet), make sure you don't get confused between the capacity of a battery and the energy in a battery. Energy = Capacity*Voltage.

A good example is with a 1.2V 2000mAh Eneloop and a 3.7V 750mAh 14500 Li-Ion. The li-ion has much less capacity, but it actually stores more energy:
1.2V*2Ah = 2.4Wh (Eneloop)
3.7V*0.75Ah = 2.775Wh (14500 li-ion)

 

[357mag1]

Relax boys.....we are getting a bit off topic.
I was asking which SIZE cell the CPF recommends.
1 18650 at 2400ma, OR 2 cr123's at 700ma.

Results will vary with lights depending on their circuits. Using an Olight M20 which is very well regulated with both battery types the current draw with an 18650 is 970ma and 2x16340s is 540ma (both AW).

If we can assume the ratings of 2600mah for the 18650 and 750mah for the 16340 are accurate that gives a runtime of 2.68 hours with the 18650 and 1.39 hours for the RCR123.

The above numbers are good for comparison but in real world the current draw will vary with the voltage output so it isn't exact but gives you an idea.

Hope that helps.

 

[Linger]

Unfortunately there are too many unrestricted variables in your question:

Capacity - Hoongern illustrates the 18650 may contain more energy that is potentially available to the emitter

voltage - different emitters have different efficiencies, but most importantly the driver (circuit board) may have a range of input efficiencies. Driver efficiency may vary from %40 to %89 across its input range. You need to figure driver characteristics before choosing appropriate voltage

battery health, the internal resistance of the batteries - 2 cells at a lower drive current (but higher voltage) may face less resistance then a single battery at a higher draw. With cheap batteries it is hard to tell. Further, 2 cells may sag less under load, or the sag may be beneficial if it drops the vbatt into a higher efficiency range for the driver. A single cell may sag below the driver's required current and your light could never run in regulation and you'd never get full performance on high.

Battery rattle, additional resistance because of the 2 contact points, possible reverse charging and 'vent with flames' occurance.

anyway, lots of questions, but perhaps you don't need to answer any of them:

If you want a cell that performs well over time, is reliable and consistent, pay for it. Spend the extra $ and buy a quality cell. You may very well find a larger performance difference between a premium cell vs. a discount xxxfire cell. I mean, it may not matter as much if you get 18650 or 2x16340's if they're of poor quality: you will receive better performance across the board by using a quality cell.

Lastly, you will never know what quality the discount, cheap cells are until you have bought them and they have failed. Different brands and different product lines are discount re-sales of cells that failed quality control from a premium manufacturer. Did the cell fail because the internal resistance was too high, because it was over-crimped, or because the wrapping wasn't straight?

If you want a battery to perform, pay for it. e.g. an AW 18650p (2600ma)

 

[BeeMan458]

While waiting for the RRT-3 pre-order to be filled, today I ordered up eight two packs (16/ea) of the protected TrustFire, 18650, True 2400mAh batteries from DealExtreme. At $5.28/ea., delivered, it seemed like a screaming good deal.

http://www.dealextreme.com/details.dx/sku.20392

Independent tests that I read yesterday and today (independent of CPF) wrote that the readings were pretty darn close to the TrustFire rated 2400mAh when under a 5A load such as what the RRT-3 would demand of it's power supply source. Based upon specs posted on BugOutGear, this gives the RRT-3 (700 lumens out the front) a hundred and five minute run time. DrDuce, this sounds like a good thing.

FWIW, I have a 502B, with an incandescent bulb installed and it runs much brighter with the higher, unregulated voltage provided by a pair of CR123A batteries than a single 18650.

:thumbsup:

 

[DR_DEUCE]

GUYS.....thanks a bunch for all the thoughts.........I have many answers, and some more confusion. Very much appreciated!!!!!

 

[mdocod]

Safety warnings first:

The charger that has been linked to above (DX SKU 6105) does not terminate the charge and will trickle a cell to ~4.26V (give or take) without ever stopping the trickle to hold the cell at that voltage. This charging method is not recommended by li-ion cell manufactures and can lead to the conversion of lithium oxide (ions) into metallic lithium plating on the anode. This conversion process can lead to chemical instability within the cell, which can eventually lead to fire or explosion.

It's easy for folks to post a quick link to a cheap charger on DX but very time consuming for someone to go around and "clean up" after the fact.

If you choose to purchase the charger, you can increase your safety margin considerably if you do 2 things:

1. Always monitor the charge, try to remove when the light turns green. Leaving them on any longer is going to be harder on the cells.
2. Possibly attach a timer to the charger that will kill the power that the charger is being fed after like 2 hours (modified up or down based on state of charge).

You may want to have a look here to make a decision on which charger to purchase

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

In response to the original question:

Most LED flashlights that support either 2xRCR123 or 1x18650 will operate as follows.

2xRCR123: Maximum output for 45-60 minutes run-time. No diminishing output. Followed by sudden shut-off by PCB in cell.

1x18650: Some units will be as bright fresh off the charger as 2xRCR123, some as much as 30% or more dimmer. Most will steadily diminish in output through the discharge to about 50% of the initial starting point on the 18650. The resulting run-time can be anywhere from 3-6+ hours depending on specific behavior of the flashlight in question.

In some specific cases, which is usually advertised by the manufacture, the light will run in regulation on both. I'm only aware of 1 light that does this, and it's made by EagleTac and achieves this ability by using selected low Vf LED emitters and a very well designed buck regulator with minimal over-head voltage requirements.

Best of luck on your quest for your optimum rechargeable configuration. Be Safe,

Eric