Rechargeable Li-Ion Battery Notes

This is a look at the AW ICR 123 750 mah lithium ion (LI) rechargeable cells that I use every day in a 4sevens Quark 123, a state of the art, single-cell LED flashlight.   I have two AW ICR 123 cells whichI use alternately to power this light.

The AW ICR 123 battery has built in integrated circuit (IC) over-discharge (OD) protection Does it work? Yes. I have used these cells to the point where the OD protection kicked in  somewhere between 2.5 to 2.8 V under load. A meter shows that after a few minutes, the cell gradually recovers to a resting voltage of 3V. There is a concensus on CPF that this is the correct behavior for an OD circuit.  At the same time most consider running down an li-ion cell this low to be damaging to the cell’s longevity.  Some of the more hard core CPF’ers would even throw out a cell that has gone this far.  What I’ll do is to do whtat most people do; continue to use the cell, rely on the built in protection of the AW, and replace the cell if it’s longevity drops unacceptably.  Otherwise the conventional wisdom of CPF is that the AW is about the best cell for longevity.  It would follow that this could be because of its OD protection aka PCB (for printed circuit board).   I think the AW is a good overall value for a rechargeable cell for lights.   Costs  more, protection works as designed.   ($9 from 4Sevens, $7 from Lighthound)

Another cell that is lower in cost than the AW and with protection circuitry is  is the TrueFire Gray RCR123. This cell reputedly does not have the same QA as the AW but it is cheaper and on average has a somewhat larger mAH capacity than the AW.  As far as cell life is concerned I haven’t read much about this particular TF.  This cell is longer than the AW – there is discrepancy in its dimensions. May be a better value for the Quark’s  ($5.21 from Deal Extreme)

I use TF’s 18650’s in two other lights (Quark + 18650 tube and a Fenix TA21).  Those are proving to be really good cells, great capacity.  Problem is they are MUCH bigger than the  single 123 lights.

The AW 123 capacity is a bit lower than ideal … I get a weeks use without an OD, but  I have a few times now forgotten to charge and get the blink out as the protection circuit kicks in.  The question is how much damage is done to the cell – i.e. affecting the overall cell life.  I am in the middle of this now, we will see.  My impression is that the 123 capacity has been affected, but my records are not good enough to check this out.

CPF Thread: AW RCR123 750mAH Actual Capacity

Name   Size       V     AvgV mAh PCB amps

CR123  16340 4.2  3.7      750        5

Anti-explosion Vent/PTC Module
protection PCB with high current threshold of 5A +/- .5A
button top for better contact
steel bottom plate for wear protection

There is good information at CPF about cell capacity (in mAh) and run times under load (in minutes) in this tread.

Information  here shows that AWRCR123 750mAh cells have the best run-times over the long haul, but fall in the middle in cell capacity in the discharge curve tests under loads of 250, 500, 750, and 1000 mAh. From a practical standpoint the AW cells really have a capacity of around 550 mAh and not 750mAh.   The grey TrustFire cells are a bit larger – longer by 1.5 mm or 3mm with two cells.  This may account for their better mAh testing – possibly slightly larger cell size.

Appendix from CPF

Size Information and other info
Batterystation: 34.4*16.7
DX11670 (white TF):35.9*16.7

DX8683 (grey TF):35.8*16.6 … the grey trustfire, AKA
Trustfire Protected 16340 / 880 mAH 3.7v   36.2mm 16.3 mm (possibly some variation in size) $5.21 (8263 is the SKU #) from deal extreme (undervoltage cutoff ~2.75v)

AW:34.3*16.6  ( $6.99 at lighthound, $9 at 4sevens)

Other CPF anecdotal information
DX 11669 White Trustfire 880mAh — not good, lose capapcity – higher voltage under load but lower capacity
DX 8683 Grey TF) … longer than normal and don’t fit some lights – otherwise good value protected cells, expect some quality control issues (some cells die early)
DX Ultrafire R123 880 — also gray, overall poor performance
Solarforce 880 mAh — OK
AW 750 — best
KD have been found to not hold up well

DX == “Deal Extreme”
KD == kaidomain

Lithium-ion batteries are everywhere now. If you use a cell-phone,  laptop or ipod, you use lithium-ion batteries.   If you have used these things a while or are a heavy user of these devices,  you have noticed that this years batteries are better than last year’s  batteries, but still leave something to be desired, namely capacity and durability.  Capacity determines  how long the device can be used before recharging (ideally “forever”).  Durability determines how long the battery lasts before you have to buy a new one (ideally, also forever).   Here in the real world batteries have limits on capacity and durability.

LI also has limitations that raise safety concerns for the average person for certain uses, like flashlights.

The main problem with LI in general is that if the cell is drained (discharged) past a certain point, it can become chemically unstable, short out internally, and burn itself up, or worse yet, explode. The second main problem occurs when recharging the cell: if recharged past a certain point (overcharged), it can become chemically unstable, short out internally, burn itself up, or explode. As long as one stays away from these danger zones however, the technology is perfectly safe.  Before getting too worked up, LI is used everywhere from BlueTooth devies;  you put the device with it’s LI battery in your ear;  cell phone (the LI battery device is next to your head), and laptop computers (in your lap).  But rest assured, the manufacturers have these Li-Ion devices well under control so you don’t often hear of a problem known in the industry as (ahem) ignition.

This is not true of the hobby applications however  like radio controlled cars, airplanes, helicopters, or flashlights.  Here size and weight restrictions, and the hobbiest’s notorious tolerance for danger, drive a market for applications that are not fully protected, and this is true of flashlights.

Lights in particular are driven by design compromises in a fickle market.  There is a market that wants to use primary cells and not rechargeable ones.   Primary single use cells, unlike the li-ion cells, can be discharged to zero like any other cell without danger.  Much of the world prefers this ease of use.  Hobbyists, OTH, like rechargeable cells because they are cheaper to run over the long run, because they are the state of the art, because they are “greener”, as well as more demanding technically, and therefore more interesting.


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