My first unprotected cell - need advice! (started life as a protected RCR123)

[Matt7337]

Afternoon all, I just have a quick story and question about one of my RCR123 cells. When I first got into flashlights a couple of years ago, I bought my supply of rechargeable cells for the lights that I had and the ones I intended on getting. That was a total of 6 cells - 3x RCR123's and 3x 18650's from AW. A while ago one of those 123 cells stopped working. At first I thought it was the flashlight that had gone but I put a new primary cell in it that day and it worked fine.

The RCR123 wouldn't take a charge after that, and wasn't reading any output voltage either. So I shelved it for ages - it sat in one of my battery caddies for well over a year. I found it whilst I was clearing out my battery drawer the other day, and decided for the sake of interest to take the black wrapper off it and have a look at the protection circuit. When I had it stripped back, I put a voltmeter on the actual terminals of the cell - bypassing the protection circuit - and it read 2.8 volts. Remember that this was the cell that read zero volts on my multimeter using the outer terminals before.

So, I decided to chance it and removed the protection circuit from it along with the small connecting strip for the +ve contact, and put it in my Ultrafire WF-139 charger with an aluminium spacer to make it up to 18650 size. It began charging immediately, so I turned it off and put a DMM on it to monitor the voltage through the charging cycle. It charged all the way up to 4.25 volts, at which point the charger stopped, as expected.

I have it in my Nitecore Extreme now and it's working perfectly. My question is this - I know the WF-139 charger protects cells from over charging but which (if any) of my CR123 sized flashlights (see sig) will protect this cell from over discharging below 3V?

I know some of you may not exactly be thrilled at hearing that I pulled the protection circuit out of a protected cell, but I only have 3 of them and I really needed this one working - the protection circuit was obviously faulty and I didn't damage the actual cell in any way, and I closely monitored the charge cycle of the unprotected 123. I really need to buy some more AW cells now though. I have way more lights now than I had when I bought the 6 AW's that I have

Thanks in advance for any help or advice.

 

[Bat]

AW

 

[Matt7337]

I thought AW cells were supposed to be good! Or are you making the joke that "AW" sounds like "Awwww"?

 

[Lightfoot98]

I have some DMM probes that I sharpened up the tips that I use to poke thru the cell wrapper to get a reading on the case (neg term) bypassing the protection circuit. That way I don't have to destroy the wrapper. just 1 small pinhole.
When the circuit trips at <3v, battery is unuseable.
As long as it is above 2.5v, I'll go ahead and put a slow trickle (less than 150ma) on it thru the sharpened probe to bring it up to 3+v, then the
protection circuit kicks in and it can be charged as normal.

Most protection circuits protect anywhere from 3.0v down to as low as 2.5v, depends on mfg.

Anything I read as less than 2.5v, I recycle/discard.
Less than 2.5v stresses the cells and they could be unstable, re dangerous.

Most modern premium LiOn chargers have a pre-conditioning circuit that senses when the cell is below 3.0v and gives them a
gentle low ma charge to get them back up to 3V before going into full charge mode.
Some will even do this down to 0v (I don't like it this low myself)

I'm not endorsing this, Just a suggestion, as some might think it as unwise/dangerous.

Google "LiOn charging" to read info on charging practices and hazzards.

BTW, I check voltages on my cells every 6 months and put a slight charge in them to bring them all up to 3.8-3.85v as a storage
charge. They will self-discharge down to a dangerous/unuseable voltage all by themselves if unattended.


Most flashlights do not have protection circuits built in, although some of the better ones do.
Should be stated on spec sheet in manual if it came with one. (or on box)

Protection circuit probably was not faulty, just doing it's job.
Some will reset when a voltage of 3+v is applied to cell, some won't untill cell itself is above 3v.

You can google "LiOn-LiPo protection circuit" to find out more.

 

[Matt7337]

LightFoot - thanks for the "tip" ('scuse the pun) on the sharpened DMM probes. I know for sure that the protection circuit was faulty, because the cell had been freshly charged the previous night and used briefly that morning, it just stopped working all of a sudden around lunch time, the light just wouldn't come on. No way it could have been over discharged because it was in a "smart light" (RA Twisty 85Tr) and had only been used on red low that morning to read something in the car. I went to switch it onto high a few hours later and nothing happened.

I'm not sure which of my lights have over discharge protection - I would assume that the HDS Clicky 170 has it, as well as the Twisty 85Tr, given that they switch modes down to a safe level as the battery discharges. I also think the Bitz lights as well as NEX and Nitecore EX10 include it but am not 100% sure - that's why I posted this topic, becuase I don't want to use my unprotected cell in a light that does not cut off at/above 3V.

 

[Lightfoot98]

Yea, some lights go into a low output mode and some even blink to let you know the cell is low.

Best to google search models or even contact mfg to find out for sure.

 

[Matt7337]

Yeah, I'll have to go and read up on it more. There's a fairly good chance I am confusing regulation with battery protection here - or do the two come hand in hand?