Two RCR123As in series?

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joema

Flashlight Enthusiast
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I noticed BatteryJunction has a Striker-VG packaged with two RCR123As and a charger: http://www.batteryjunction.com/ledlostvgtaf1.html
Apparently they're 750 mAH protected cells: http://www.batteryjunction.com/rc375reliba.html

However I thought you never should use RCR123As in series? Are there specific conditions where this is safe?

Could I safely put those batteries in my U2?

I thought the problem was non-protected RCR123As in series could over-discharge the weaker cell (with fire/explosion risk), whereas protected versions could trip the protection, disabling the battery. Therefore in either case (protected or non-protected) RCR123As in series is problematic. Am I wrong about this, or could someone explain further?
 
if they are protected there is no propblem, they will only trip the protection once they are dieing to prevent overdischarge and damage the cell.

for a U2 i would think you would be far better off using 1 18650 or 17670 cell, but someone will let you know if 2 rcr123a will work(i dont know)
 
Hello Joema,

The same rules apply for using all battery chemistries in series.

1. Use cells that are the same capacity.
2. Use cells that start off at the same state of charge.
3. Make sure your low voltage cut off is high enough to prevent cell reversal.

Protected Li-Ion cells offer a second layer of protection. If you low voltage cut out fails to function, the protection circuit in the cell will kick in before the cell is totally ruined. It is my opinion that running Li-Ion cells down to the protection circuit cut off every time does some damage to the cells and you will get reduced life from your cells by doing that.

Charging Li-Ion cells in series (or charging cells that have been over discharged) is where things can get dangerous...

Tom
 
I've used these 900mAh rechargeable Li-Ion batteries in series within a flashlight with no problems. These batteries, like the 750mAh versions, are fully protected. So there is little chance of "problems" occuring except for fairly quick shutdown of the batteries to prevent overdischarge.

As these (Tenergy 750mAh & 900mAh) batteries are regulated to provide about 3 volts each, I don't see any problem in using them in just about any LED light that normally takes primary lithium batteries (including the U2).

The main disadvantage of these rechargeables is their limited capacity ( up to 900mAh) compared to higher capacity primary batteries (up to 1500 mAh). This usually means less light runtime while using these rechargeables.

Alternatively, the "17670" 3.7 volt Li-Ion rechargeable batteries are equivalent in size to two primary batteries in series, and are rated at about 1600mAh. These rechargeables may produce similar runtimes (give or take a bit) to those runtimes produced by primary batteries. But because the voltage of these rechargeables is lower than the primary batteries, the light output may drop a bit as well. It is my understanding that these 3.7 volt rechargeables can be used in U2's.
 
For your U2, don't use normal 4.2v RCR123 cells - you will overdrive the LED and controller circuit. The 3.0v limited RCR123 cells will probably be fine, but you give up a substantial bit of runtime to get the voltage limiting.


Best bet for the U2 is definitely the 17670, or the 18650 if it will fit yours.
 
I just received this charger and cells today. I don't have a ZTS that can test 3V lions, but I do have a DMM. Interestingly enough, the two cells that just finished charging read 3.7V and 3.9V "hot off the charger." If it matters to anyone, the charger was air-cooled the whole time to around 65F. I tried a freshly-charged cell in my P1 and couldn't visually detect any difference in brightness. Just out of curiosity, I measured the voltage of the uncharged cells, and they were all around 3.8V, just like the fully-charged cells. Do these Tenergy (or similar) cells always stay at around 3.8V?

Here's my big question: will these cells be safe to use in my soon-to-arrive Gladius? I've heard that the maximum voltage is seven volts, and 3.8*2=7.6. I've heard that the so-called 3.7V RCRs are around 4.2V hot off the charger, so my new cells are definitely less than that. Is the voltage low enough, though?

The Gladius is my most expensive light by a huge margin, and I don't want to fry the LA and the warranty in one fell swoop.

So, meeshu, are you sure about your second paragraph in post #4?
 
TigerhawkT3 said:
I just received this charger and cells today. I don't have a ZTS that can test 3V lions, but I do have a DMM. Interestingly enough, the two cells that just finished charging read 3.7V and 3.9V "hot off the charger." If it matters to anyone, the charger was air-cooled the whole time to around 65F. I tried a freshly-charged cell in my P1 and couldn't visually detect any difference in brightness. Just out of curiosity, I measured the voltage of the uncharged cells, and they were all around 3.8V, just like the fully-charged cells. Do these Tenergy (or similar) cells always stay at around 3.8V?

Here's my big question: will these cells be safe to use in my soon-to-arrive Gladius? I've heard that the maximum voltage is seven volts, and 3.8*2=7.6. I've heard that the so-called 3.7V RCRs are around 4.2V hot off the charger, so my new cells are definitely less than that. Is the voltage low enough, though?

The Gladius is my most expensive light by a huge margin, and I don't want to fry the LA and the warranty in one fell swoop.

So, meeshu, are you sure about your second paragraph in post #4?
Click to expand...
The ZTS can't check Li-Ion cells, only CR123A lithium primary cells.
 
all U2 with internal liners supports single 18650.

from reports, latest version has no liner, so you need to use 17650 instead.

assuming you have older version of U2. 18650 is the way to go VS 2x R123. why risk killing your U2 with 2x R123, when 18650 is much safer and better?

better to chose single cell lithium configuration over mulitple in series. if you have a choice, for reasons silver just posted...
 
Silverfox,

I am just now taking the Li-ion rechargeable plunge after enjoying the use of Nimh AA in first my digital camera and now led flashlights (Fenix L2T). I just received a Tenergy RCR123a 3.0V charger and four 900mah batteries. The two batteries that were in the charger read 0.00V on my DMM. The two batteries not in the charger read 3.77V & 3.78V (close to fully charged). These are advertised as fully protected and should not have discharged below approx. 2.5V. I read in your post above that charging a very discharged battery could be hazardous and I have had bad luck reviving Lenmar Nimh AA 2000mah batteries that came out of the packaging in the 0.65V to 0.85V range. Should I attempt to recondition these 0.0V cells or ask for replacements.

Thanks, Kippers :candle:
 
meeshu said:
Look here, about 2/3 down.

Apparently the 3V(loaded) protected RCR123's do work!
Click to expand...
I've read through that entire thread before you mentioned it, and have even posted to it already.

However, I can't quite find the part you mentioned. Might you possibly have a post number for me? :whistle:
 
This is an often discussed problem. Not only with the Gladius.
The fact, that one or a few people tried critical RCR configurations in their lights and they worked does not mean, that this is a safe way to use the light in longterms.
A lux III, used with the configuration it's create for, should last up to 100000 hours.
When the same led will be used at such a critical configuration it could be (only a thesis) it will lasts only 100 hours.
So if a user needs his light for one hour a week, it could work for nearly 2 years and about 100 charging cycles.

There are also a few different factores. How often and how long using the max brightness level (or interrupted).

IMO it's a lottery and it's everybodys own decision, to play this lottery.
I for myself can tell, I would'nt play this game with a light in this pricerange.

This could be a helpfull thread:

http://www.candlepowerforums.com/vb/showthread.php?t=104388&highlight=Gladius+RCR123

Best regards

____
Tom
 
Hello Kippers,

Your cells that read 0.0 volts have tripped the low voltage cut off. Put them in the charger for a minute or two and then check them again. They should read higher.

Sometimes you have to insert them a few times to reset the low voltage cut off circuit, but it should bounce back up to above 2.5 volts.

If they do bounce back up, they should be fine. If they do not, then you should replace them.

Tom
 
Tigerhawk, I have the exact batteries and charger you have and have been using them in my Gladius for awhile now with no problems. They just don't last as long as regular batteries.
 
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