Over-discharged IMR 18350 now only at half brightness?

I have a Jetbeam RRT-01, and a visitor accidentally left the ring half-on for a few days, completely discharging the IMR chemistry 18350.

After I found it, I immediately put it in a Pila charger.
After several hours, I found the Pila charger flashing a red light very rapidly, rather than giving a constant green light.
What does this rapidly flashing red light mean?

I then placed the supposedly fully charged IMR 18350 into the RRT-01, and I found it turns on normally, but has only half the maximum brightness.
I have another IMR 18350 battery of the same age, purchased at the same time, and I put it into the RRT-01, and it turns on with the full brightness.

My Fluke 87V measures the good IMR 18350 A at 4.11 volts, while the overdischarged IMR 18350 B was only 1.27 volts!

What is happening?
Can I rejuvenate the over-discharged IMR chemistry 18350 battery, or is it permanent loss of full brightness?

Maybe the charger won't recognize the cell at it's discharged voltage. You can take a equal charged cell and attached it in parallel with your discharged cell for a few seconds to surface charge it. The voltage may rise enough for your charger to accept it.

Can you define "completely discharged?" What was the voltage?

I tend to be conservative with Li-ion. I would err on the side of safety, discarding (i.e., recycling) a battery that had been discharged below the lowest voltage it was rated for.

Joe Kidd said:

Maybe the charger won't recognize the cell at it's discharged voltage. You can take a equal charged cell and attached it in parallel with your discharged cell for a few seconds to surface charge it. The voltage may rise enough for your charger to accept it.

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Just trying that now.
Now, the Pila is on a constant red light.
Not sure what will happen with time, like in an hour or so?

KeepingItLight said:

Can you define "completely discharged?" What was the voltage?

I tend to be conservative with Li-ion. I would err on the side of safety, discarding (i.e., recycling) a battery that had been discharged below the lowest voltage it was rated for.

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In other words, the RRT-01 was kept constantly on, despite a flat battery.
I never checked the voltage when I took the IMR 18350 out.

Just that after a few hours of charging on the Pila charger, the Pila did a rapid red blink - what ever that means?
Furthermore, there is now only 1.27 volts in the IMR 18350, and when inserted into the RRT-01, it will only light up at half the maximum brightness.

Is 1.27 volts excessively low, such that the IMR 183509 should be discarded?
Is this to prevent explosion and fire?

Btw, why is there no protection IC in these IMR 18350?
Is that because the IC circuit will reduce the mAH capacity even more?

If you can't surface charge the cell quickly up around 2.75-3.00v I would trash it.

peterharvey73 said:

Just that after a few hours of charging on the Pila charger, the Pila did a rapid red blink - what ever that means?

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Red blinking means "bad cell", i.e. the microcontroller in the Pila decided your cell is broken/can't be properly recharged. Without knowing the programming logic and without data from your 18350 it's impossible to say why exactly.
1.27V is excessively low for LiIon and the cell might be internally damaged. Toss it.

Unprotected batteries in flashlights without their own protection logic always need a little bit more care (e.g. don't hand them to strangers).

Joe Kidd said:

If you can't surface charge the cell quickly up around 2.75-3.00v I would trash it.

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I did as you said, and recharged both the good IMR 18350 A and IMR 18350 B in parallel on the Pila charger.
For some strange reason, both red lights were constantly-on for each channel.
After a few minutes, I took the good IMR 18350 A out, because it was already above 4.1 volts.
However I left the bad IMR 18350 B which was only 1.27 volts to stay.

After half an hour or so, I turned the Pila off, and took the bad IMR 18350 B out; I checked the voltage on a Fluke 87V - now it is 3.6 volts!
So I have put the bad IMR 18350 back into the Pila, and will leave it a few hours.
Hopefully a constant green light comes up?
And hopefully it registers 4.2 volts on the Fluke too???

The task I mentioned is done outside of the charger with the cells only, kind of a "kick" start if you will. It doesn't always work and should be used with caution. You may have a damaged cell.

Joe Kidd said:

The task I mentioned is done outside of the charger with the cells only, kind of a "kick" start if you will. It doesn't always work and should be used with caution. You may have a damaged cell.

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Ditch it, it's only a few dollars and start over. Give your coworkers AA based lights!

Been there, done that.

Life's too short to muck around with fully discharged li-ions.

Chris

Joe Kidd said:

The task I mentioned is done outside of the charger with the cells only, kind of a "kick" start if you will. It doesn't always work and should be used with caution. You may have a damaged cell.

Click to expand...

ChrisGarrett said:

Ditch it, it's only a few dollars and start over. Give your coworkers AA based lights!

Been there, done that.

Life's too short to muck around with fully discharged li-ions.

Chris

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That's it.
Fully recharged to 4.14 volts now.
Tested inside RRT-01, the previously discharged IMR 18350 B works nice and bright just like IMR 18350 A.

Lucky shot.
If it didn't work, I'd just purchase another IMR 18350.
I was more afraid of an explosion or a house fire trying to recharge a fully depleted IMR 18350...

Just one other question.
As my Jetbeam RRT-01 ages, its maximum brightness seems to be dimming.

Is this due to the age of the LED emitter?
Or is this due to the age of my IMR 18350's?
It also seems that the maximum voltage of my IMR 18350's immediately after charging has fallen from say 4.3 volts, to just 4.14 volts now; am I right that the maximum voltage immediately after charging is falling???

peterharvey73 said:

Just one other question.
As my Jetbeam RRT-01 ages, its maximum brightness seems to be dimming.

Is this due to the age of the LED emitter?
Or is this due to the age of my IMR 18350's?
It also seems that the maximum voltage of my IMR 18350's immediately after charging has fallen from say 4.3 volts, to just 4.14 volts now; am I right that the maximum voltage immediately after charging is falling???

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I would presume the emitter or the driver.

4.14V is still more than enough volts for the driver/led to work at their intended outputs.

Pila chargers are known for under charging. My Pila charges on one bay to 4.18 & the other only to 4.15V.

peterharvey73 said:

That's it.
Fully recharged to 4.14 volts now.
Tested inside RRT-01, the previously discharged IMR 18350 B works nice and bright just like IMR 18350 A.

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Still could be a ticking bomb since copper dendrites may now be growing.

FroggyTaco said:

I would presume the emitter or the driver.

4.14V is still more than enough volts for the driver/led to work at their intended outputs.

Pila chargers are known for under charging. My Pila charges on one bay to 4.18 & the other only to 4.15V.

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I will try to recharge with my all new Nitecore D4 charger next time.

Gauss163 said:

Still could be a ticking bomb since copper dendrites may now be growing.

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I guess I should throw the overdischarged one away.
Else, always recharge it while I'm awake and nearby, and never recharge in my absence.

To be true, IMR chemistry is claimed to be much more safe than widely used ICR. IMR batteries have no protection because of that. IMR gives a little bit less capacity, but way much more current.

I may be wrong, but IMR does never "Poof!". Overdischarged it may suffer overall lifetime, but nothing more.

A very long read -- "Why do Lithium-Ion batteries die": https://batterybro.com/blogs/18650-...3090502-why-do-lithium-ion-batteries-die-long

Thanks for that tip Vadimax.
Perhaps I'll keep that questionable IMR 18350 B afterall.
It shone brightly last night.
Could be my Pila charger not charging properly.
Will have to try out my new Nitecore D4 with special 500 mA recharge mode for small capacity batteries.

vadimax said:

I may be wrong, but IMR does never "Poof!". Overdischarged it may suffer overall lifetime, but nothing more.

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You are indeed wrong. Where did you get that idea?