Qs about recharging RCR123s and nano charger

[manoloco]

I was a bit negligent with a couple of my AW rcr123s black label, they were discharged for a while and i left them like that for months, now they seem unable to hold a charge.

last time i tried charging them (2 days ago), it took more than 8 hrs and the green light on the nano charger didnt come, so i unplugged the thing from the wall, tried the cell and light came up on my HDS U60 but as soon as i hit high, the light goes off, to not come again, at any level.

ditto for the other cell

now as both cells seem to be dead, could this be due to those months i left them discharged?, or maybe the light (which i modded with a seoul p4) could have damaged the batteries due to my mod in any way? (like using them right after modding it, maybe too hot?)

and my other question is: i dont remember if it was like this when new but theres an electronics toasty smell that i can perceive if i place my nose very close to the cell compartment in the nano charger, maybe something is burnt inside?, should i get another charger? (dont want to risk an accident or damage my other cells)

what are the possible scenarios?, only thing i know i should not do is ever use or charge those 2 cells again.

thanks in advance.

 

[manoloco]

little bump, sorry if this is annoying.

 

[SilverFox]

Hello Manoloco,

Leaving a Li-Ion cell in a discharged state for an extended period of time will usually render them unusable.

You need to find a voltmeter and check the cell voltages. There is a possibility that the protection circuit has malfunctioned, but this is just a slim chance of being what has happened.

Most likely the cells are dead, but it is worth checking just to be sure.

If you have any question about the condition of your charger, I think you should replace it.

Tom

 

[manoloco]

Thanks SF, i will buy a voltimeter (long time thinking about buying one, good reason to do it already) and test the cells, though i doubt the protection circuit failed coincidentially in both cells at the same time, i am afraid those 2 are goners (a pity since i really like those cells).

about the charger: yup you are right and at less than 10 bucks it would be easy to replace, however i should test it with the voltimeter too, what readings should i be getting from a 123 AW nano charger?, and if the readings are ok what are the chances of it being ok? (i do think other things might malfunction, like cell topping detection and such, am i correct?)

once again thanks, you can never take safety for granted with electronics, much less with cells.

 

[manoloco]

bump

 

[zipplet]

and my other question is: i dont remember if it was like this when new but theres an electronics toasty smell that i can perceive if i place my nose very close to the cell compartment in the nano charger, maybe something is burnt inside?, should i get another charger? (dont want to risk an accident or damage my other cells)

My nano charger does this and it's brand new. It's not an unpleasant smell, more like a hot PCB/electronics smell. My charger gets warm but not abnormally hot. I don't think it is an issue - my sealed lead acid charger does it too, as does my TV when it's been on for a while.

Hope this helps.

 

[mdocod]

Test the voltage on your cells. Unfortunately there is very little else we can tell you without this information.

Eric

 

[manoloco]

both read 0.00, sometimes they give me a negative value like -0.01

im planning to properly discard them, how do you discard your spent, or malfunctioning lithium ions?

also im more interested on knowing if my charger is ok, is there a way to test that?

 

[LumenHound]

Pop each cell into the charger for ten seconds only and then check the cell's voltage after you pull them out.

Still the same zero volt reading?

If so, what voltage do you get across the the metal tabs of your nano charger while the battery is in place? 4.2V?

 

[manoloco]

2.73 in one cell
2.88 on the other

while charging on the metal tabs i get those same values:

2.73 with one cell
2.88 with the other

thanks for replying!

 

[mdocod]

yea, the low voltage protection kicked in, resulting in the 0V reading, a bump on the charger brought the cell voltage up above the bottom end range for the PCB to close the circuit to the cell again..

if they've been sitting like this for awhile, they are probably not going to come back to life...

based on what you described in the OP, i'd suggest retiring them.

 

[manoloco]

thanks for the reply, have to learn a lot about cells... i know some precautions, but im a bit more interested now.

Mdocod, do you think the charger is all right to use with my other cells?

also what is the best way to dispose of the cells?, i dont think the battery recollection bin near my house on the local market is a good option, specially living in a third world country were there is less knowledge of this kind of chemistry.

 

[mdocod]

Anywhere they take cell phone batteries would be a good place to get rid of em.

As for the charger, it very likely is fine.

Since you have a volt meter you can check this when you get new cells. Just make sure that it is charging the cells to ~4.10-4.20V.

Eric

 

[manoloco]

thanks for your recommendations mdocod, i already received a couple more of AW protected RCR123 750mA cells, will test using that, keeping an eye on the charge.

glad to have you guys so newbies like me dont

one question, i saw a thread were AW recommended some other poster with my same problem (he didnt of course had the cells sitting uncharged for so long) to reset the pcb?

i assume he means resetting the protection circuit, but how do you do that?

 

[manoloco]

I checked the voltage across the nano charger, no battery, it was putting out around 3.09V, im thinking the culprit can be the nano charger, and its no longer working properly, i tried an ok not completely spent cell and after 3 hours didnt raised the initial reading of 3.26V, what do you guys think its happening, any chance the other cells could be ok?.

in the meantime im getting another charger, possibly a wf-138 or a wf-139, since i only need to charge RCR123As i will probably go with the ´38.

thanks for your responses!

 

[zipplet]

That nano charger sounds faulty. Open circuit it should show ~4.2V.

Edit: Unless it's a nano charger designed for LiFePO4 cells - although I thought they had to charge to 3.2V?

 

[manoloco]

yup i dont know what caused its malfunction, but already ordered a wf-139. hope i can still use the cells, seems to me they probably were ok all along... can this be the case? (i only have one charger, that faulty nano)

 

[mdocod]

Hard to say, It's possible that a charger design could in fact deliver a lower open circuit voltage, and then "crank up" to charging voltage when a load is applied. Especially if the charger is waiting to take a voltage reading of the cell before charging, it might not want to have a high open circuit voltage that could change that initial reading too much.

Disclaimer: The above is what I like to call- a bumm extracted guess.

 

[manoloco]

mdocod: i can see what you mean, however, it cant charge a cell that i have tested to be ok, it remains at 3.26V after 4 hours of charging; i definitely lean to believe the charger is faulty, however to say i am a newbie and can be wrong is definitely and understatement.

 

[mdocod]

It sounds like the charger is busted, I was just pointing out that it's possible that an open circuit voltage reading might not be an accurate way to figure out if it is broken or not, definitely sounds like the charger is bust