Err...my AW R123 is now reading 3.183V and won't charge?

[GarageBoy]

I used it for about one charge and now it's reading 3.183V? I thought the circuit was supposed to prevent over discharge?

 

[RedForest UK]

Yes, but the circuit cuts in at roughly 2.75v I believe. It's designed as a safety feature to prevent really deep discharge not a general purpose indication of when to charge up again..

Have you let the cell sit for 15mins or so? The voltage should 'bounce' back up to about 3.6v if you measured it at 3.1v straight out of the light. :thinking:

 

[march.brown]

I used it for about one charge and now it's reading 3.183V? I thought the circuit was supposed to prevent over discharge?

You should be avoiding over-discharging and over-charging ... The protection circuit is there just in case somehow you don't (or can't) avoid it.

Is your charger working OK ? ... Some chargers won't charge if the battery voltage is outside their limits ... Perhaps you could try a cheap charger , but keep an eye (or finger) on the cell temperature.

If the circuit has tripped , it is possible to momentarily parallel that cell with a good one for a second or so to try to reset the protection circuit ... Positive to positive then at the same time negative to negative ... Use paper-clips to make the connections.
.

 

[GarageBoy]

The cell was used in a Quark 123^2, but with a 1 cell body.
My WF 138 has charged by other R123 perfectly to 4.18V.

 

[RepProdigious]

At what kind of discharge speed did you use the cell?

If you were - for example - discharging the cell at a mighty 1A current draw then the voltage would have sagged quickly tripping the safety 'on time'.

If you however were discharging very very slowly the voltage drop would have been negligible and you could have actually discharged the cell past the point of no return (2.75V could actually do damage to the cell).

In the first case, let the cell sit for a while, try to recharge and if that fails try to 'jump-start' the cell as suggested. If this still doesn't bring it back to life you could try sending it back to AW under warranty.

If however you actually discharged the cell too low its just bad luck for you and you've learned a valuable lesson; Its called a safety, not a feature. Do not rely on it!

 

[GarageBoy]

I used it at the 1A draw, but only intermittently (on and off over the course of 3 months)

 

[Ragiska]

I used it at the 1A draw, but only intermittently (on and off over the course of 3 months)

and there's your problem. lack of user monitoring and maintenance for li-ion cells is big no-no #1.

 

[GarageBoy]

I paralled them and got it to charge. Wish me luck

 

[RepProdigious]

I used it at the 1A draw, but only intermittently (on and off over the course of 3 months)

This could indeed have caused the problem..... Every time after you use a cell its voltage will recover slightly (but it isn't getting any fuller). When using a cell like this it should be recharged at around 3.5 volts at rest but the safety will only kick in at around 2.7~2.8V and if the cell has already done its recovering trick many many times chances are that it will not recover after being discharged this low (and it could for example only bounce back to 3~3.2 volts).

But great to hear you got the cell to charge! I hope you didn't let it sit too long at this low voltage? When its full (4.2V) set the cell aside for a couple of days and remeasure the voltage, it should still read around 4.2V.

 

[GarageBoy]

Thanks, will do. I thought I could just leave them charged up and ready to go in my light
Didn't want to charge/discharge them too often

 

[Black Rose]

Didn't want to charge/discharge them too often

Li-Ion cells prefer frequent charging/topping up versus running to empty and then charging.

 

[45/70]

I thought I could just leave them charged up and ready to go in my light
Didn't want to charge/discharge them too often

Hi GB.

You can do that, and many people do. For some, it just isn't practical to have a light around that doesn't have fully, or nearly fully charged cells in it. The drawback is that storing LiCo Li-Ion cells in a high state of charge causes them to deteriorate more rapidly. If you were to charge your cells to only 4.10 Volts (or run them down to, before storing), instead of 4.20 Volts they would last quite a bit longer.

On another note, charging and discharging Li-Ion cells in and of itself, isn't really what wears them out so much as the depth of the discharge. This is what has a larger effect. All chemistry of Li-Ion cells are favorable to shallow discharges, as opposed to deep discharging. It is the amount of "stretch" that wears out cells, more than how many times they are placed on the charger. A cell that is charged to 100% and discharged to 50% (~3.85 Volts for a LiCo cell) will last maybe 4 times longer than a cell that is charged to 100% and discharged to 20% each cycle. So throwing your cell(s) on the charger, is not the real problem. It's how deeply they are discharged each cycle.

......When its full (4.2V) set the cell aside for a couple of days and remeasure the voltage, it should still read around 4.2V.

What Rep said is true for new LiCo cells. As they begin to age however, you will notice their 24hr rested voltage will drop lower and lower, as well as their voltage "hot off the charger" not being as high as it used to be. When a LiCo cell is charged to 4.20 Volts (or as close as you can get), and rested for 24hrs (many suggest 1/2 hr or so) and the voltage is below 4.00 Volts, the cell is considered to be at EOL, and it's time for recycling/disposal.

I'm not sure what's up with your particular cell. Perhaps it is just showing the effects of age. Most chargers will charge a cell with a voltage of ~3 Volts and won't require any "tricks" to get it to charge. Good luck with it, sounds like it has a chance, anyway.

Dave

 

[GarageBoy]

Rested 24 hrs, I measured 4.12 (compared to 4.18V fresh)
I think I'm okay and will top off from now on (habit from the NiMH days to discharge fully before recharging)

 

[Ragiska]

you don't fully discharge nimh cells either.

 

[GarageBoy]

So what should I avoid topping off on? Thanks