Just took an rcr123 out of one my lights that was so drained it wouldn't register on my volt meter. I thought I had a primary in there and purposely ran it down to nothing. Throwing it on the Cottonpicker charger the first reading was 2.6v (oh boy). I just read this thread in regards and if I understand correctly I should be good. Thxs for posting this thread, it's helpful.
How far can LiIon be discharged?
- Thread starter HKJ
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Phlogiston
Enlightened
If your RCR123 has a protection circuit, and you put it on the charger immediately after the light shut off, you should be fine. The deep discharge will knock a few cycles off the cell's service life, though.
Great thread! The back-n-forth between experts forced me to read everything carefully and led to me learning a bit. Even though some of the interaction might have been annoying to some, I actually think it made what would've been an excellent and informative thread on its own, even better.
Reminded me of the Battle of Wits from The Princess Bride. Inconceivable!
Reminded me of the Battle of Wits from The Princess Bride. Inconceivable!
Swedpat
Flashlight Enthusiast
Thanks for another great thread HKJ,
I have to say that this matter is as well interesting and important but I still don't understand all details. Sometimes it seems a bit contradictory. While the illustrations from LiIon handbook defines over discharging as <2,5V you mean it's below 3,3-3,6V depending on the model, as I understand it. And if the remaining capacity of a cell is 0% it logically should mean that it can't provide any power at all to a light. Still it seems possible to run it even lower...
Anyway; I am very pleased with the use of Li-Ion cells especially when these can replace or be a complement to CR123s in a light. Especially I like the 16650 format which is an excellent choice for many 2xCR123 lights who can't take 18650(or 17670).
Regarding the capacity of Li-Ions my personal intention is to make use of it. If I get 3500mAh cells I do it because they provide longer runtime than lower mAh models.
If regulated runtime for a certain light at a certain brightness level is 90min I find no reason to never run it more than, for example, 30-40min before recharge(like I know some flashlight users are careful to always do). If so I could get cheaper 2600mAh cells instead and they do the same job. And if the voltage of the cell now and then becomes a bit lower than it should be for the sake of keeping the lifetime in cycles as high as possible it's not the whole world. It will still work for several years.
Of course I find no reason not to fully charge a cell before use even if it's not runned low, when I have time and possibility to do it.
I just mean that I feel it can sometimes go a bit too far to never run the cells half full or less.
I have mentioned it before that I find it strange that the over discharge protection of Li-Ion cells actually is not a true over discharge protection. If it would it should not be a problem to run the cells until the protection kicks in. For example: if a cell should not be discharged below 3,3V the protection SHOULD kick in at that level.
Just my honest thoughts.
I have to say that this matter is as well interesting and important but I still don't understand all details. Sometimes it seems a bit contradictory. While the illustrations from LiIon handbook defines over discharging as <2,5V you mean it's below 3,3-3,6V depending on the model, as I understand it. And if the remaining capacity of a cell is 0% it logically should mean that it can't provide any power at all to a light. Still it seems possible to run it even lower...
Anyway; I am very pleased with the use of Li-Ion cells especially when these can replace or be a complement to CR123s in a light. Especially I like the 16650 format which is an excellent choice for many 2xCR123 lights who can't take 18650(or 17670).
Regarding the capacity of Li-Ions my personal intention is to make use of it. If I get 3500mAh cells I do it because they provide longer runtime than lower mAh models.
If regulated runtime for a certain light at a certain brightness level is 90min I find no reason to never run it more than, for example, 30-40min before recharge(like I know some flashlight users are careful to always do). If so I could get cheaper 2600mAh cells instead and they do the same job. And if the voltage of the cell now and then becomes a bit lower than it should be for the sake of keeping the lifetime in cycles as high as possible it's not the whole world. It will still work for several years.
Of course I find no reason not to fully charge a cell before use even if it's not runned low, when I have time and possibility to do it.
I just mean that I feel it can sometimes go a bit too far to never run the cells half full or less.
I have mentioned it before that I find it strange that the over discharge protection of Li-Ion cells actually is not a true over discharge protection. If it would it should not be a problem to run the cells until the protection kicks in. For example: if a cell should not be discharged below 3,3V the protection SHOULD kick in at that level.
Just my honest thoughts.
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HKJ
Flashaholic
There is a couple of points:
- Is the cell loaded, this can mean a significant voltage different, especially when the cell is nearly empty.
- Is your goal is maximum lifetime: Stay above the highest value.
- Is your goal is maximum capacity you can go a bit lower, but the difference in capacity is rather small.
- Is your goal to stay safe and you do not care about lifetime you can go down to the lowest value.
- Going below the low value may make the cell dangerous, but will not always do it.
Cell ratings is usual based on getting a decent lifetime, then on capacity (The difference is rather small).
Swedpat
Flashlight Enthusiast
Thanks for answer!
Sorry if I am dumb here, but with lowest and highest value, do you mean 3,3 vs 3,6V?
HKJ
Flashaholic
3.3V or 3.6V is not very significant, many batteries can be discharge down to 2.5V.
Swedpat
Flashlight Enthusiast
Ok, thanks!
Then I understand I don't need to be very worry about the exactly voltage unless it does not go very low. Usually my Li-ions have not been down to 3V unloaded before recharge.
Reading through all of your LiIon/NiMH charger reviews.
Do you have top 5 lists or maybe top 3 lists of your ranking best to least best charger?
i.e. top 5 or top 3 lists of 4-bay LiIon/NiMH chargers?
Maybe a list that includes chargers with fans, and a list without fans? As fans are a huge turn-off for a lot of people.
Been reading your reviews trying to decide on a 4-bay charger without a fan as I need it quiet in bedroom during the night.
Thanks
ven
Flashaholic
Sure the Xtar xp4 panzer does not have a fan, will do nimh as well. 4 bays at 1a each!.
Pretty good value, no voltage readout though..............
As much as it can be an inconvenience, it does help keep things cool and under control,especially with chargers that have higher rates and discharge options. To help keep them fairly compact, its kind of part of the package as with hobby chargers.
Pretty good value, no voltage readout though..............
As much as it can be an inconvenience, it does help keep things cool and under control,especially with chargers that have higher rates and discharge options. To help keep them fairly compact, its kind of part of the package as with hobby chargers.
KeepingItLight
Flashlight Enthusiast
Instead of 4-bay charger, consider getting an analyzer/charger. The Opus BT-3100 and LiitoKala Engineer Lii-500 both got good reviews.
samgab
Flashlight Enthusiast
Nice info kept simple for people new to li-ion cells etc. Cheers HKJ.
I wanted to mention too, that the reason for not over-discharging li-ion cells on a regular basis is not only because it reduces the usable life of the cell, although that is certainly a negative effect of over-discharging. Another big reason is the safety concerns. Sometimes it happens over time, sometimes it can happen immediately, but when this chemistry cell is over-discharged - without going into chemical details - it causes the copper metal (which is used as the current collector at the negative electrode) to dissolve into the electrolyte material inside the battery, and then when it is recharged again the copper can redistribute itself again inside the battery in such a way that it causes a short inside the cell, which can then cause thermal runaway, start a fire etc when the cell or battery is recharged. Again, this doesn't happen when over-discharging, but it creates a situation where the battery is no longer safe when subsequently RE-charged. You might be lucky a hundred times and nothing bad happens, or it might happen the hundredth time recharging, the 50th time, or even the first time recharging after an over-discharge.
So what I'm saying, in a nutshell is: There is also the safety factor involved in over-discharging li-ion cells or batteries. It can be dangerous and should be avoided, not just for the longevity of the cells, but also for safety. Stay safe out there!
-source: Lithium-Ion Batteries Hazard and Use Assessment paper, Fire Protection Research Foundation.
I wanted to mention too, that the reason for not over-discharging li-ion cells on a regular basis is not only because it reduces the usable life of the cell, although that is certainly a negative effect of over-discharging. Another big reason is the safety concerns. Sometimes it happens over time, sometimes it can happen immediately, but when this chemistry cell is over-discharged - without going into chemical details - it causes the copper metal (which is used as the current collector at the negative electrode) to dissolve into the electrolyte material inside the battery, and then when it is recharged again the copper can redistribute itself again inside the battery in such a way that it causes a short inside the cell, which can then cause thermal runaway, start a fire etc when the cell or battery is recharged. Again, this doesn't happen when over-discharging, but it creates a situation where the battery is no longer safe when subsequently RE-charged. You might be lucky a hundred times and nothing bad happens, or it might happen the hundredth time recharging, the 50th time, or even the first time recharging after an over-discharge.
So what I'm saying, in a nutshell is: There is also the safety factor involved in over-discharging li-ion cells or batteries. It can be dangerous and should be avoided, not just for the longevity of the cells, but also for safety. Stay safe out there!
-source: Lithium-Ion Batteries Hazard and Use Assessment paper, Fire Protection Research Foundation.
recDNA
Flashaholic
- Joined
- Jun 2, 2009
- Messages
- 8,761
My Keepower 16650 protected battery was at 2.65 volts when my flashlight dropped to only low mode. It may of course have been lower and bounced back to 2.65 volts by the time I checked it. Anyway is the battery safe to continue charging and using or should it be recycled due to over discharge?
archimedes
Flashaholic
How long was it undervolted (overdischarged) ?
There is a spectrum of risk. Personally, I am not comfortable with cells that have been under 3V for any appreciable duration.
https://lygte-info.dk/info/BatteryLowVoltage UK.html
https://www.mpoweruk.com/lithium_failures.htm
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ven
Flashaholic
I would put on slow 0.25a charge and keep an eye on it. I have had cells drop less and been fine. Everyone has their own safety margins, i try like archi to not let them get bellow 3v. However many cells have a min spec and measured from 2.5v. So unless bellow 2.5v and near 2v for a period, I would charge and monitor . All should be fine imo. Even at 2v, as long as not left for a long period, will still be fine.
It must be near the PCB min V? So if it's not tripped(would of course read 0v)I would keep and use .
It must be near the PCB min V? So if it's not tripped(would of course read 0v)I would keep and use .
usdiver
Flashlight Enthusiast
I m not sure if I posted previously but my Batteries in my HDS have dropped well below 2.75 and still charged up ok. In my first light Tomahawk 425 on the other hand the imr s have dropped down to 0% according to the vp4 dragon and still charged up ok. .5 amp is minimum recharge .25 would be preferred
I have 8 PKcell 14500's ,I used one of them in my LUMINTOP tool AA which doesn't have LVP & I noticed I drained the cell to 1volt something ( it was last year & can't remember the exact voltage) but I charged it up & it's been fine. I did a discharge test on all 8 cells the other day thinking I would be able to spot which one it was , but they all tested about 850mah & all 8 cells have similar IR measurements ,so I conclude no damage was done , I shoulda marked that particular cell but didn't , I have no idea now which one it was but there all fine after about a year.
WalkIntoTheLight
Flashlight Enthusiast
According to the Samsung 30Q spec sheet, it says you should not recharge a cell that is below 1.0v. Charging between 1.0v and 2.5v should be done slowly, until it's above that voltage.
But the spec sheet makes no mention of how long a battery can be left in a severely discharged state. If it's more than a few days sitting near 1v, I'd probably consider it unsafe.
But the spec sheet makes no mention of how long a battery can be left in a severely discharged state. If it's more than a few days sitting near 1v, I'd probably consider it unsafe.
recDNA
Flashaholic
- Joined
- Jun 2, 2009
- Messages
- 8,761
The PCB never tripped. I only discovered the problem when a seldom used flashlight only turned on low with no access to other modes. I would guess it was in that state for days not weeks. The pcb should trip at 2.5 but on very low output I wasn't sure it would work. The battery did recharge uneventfully to 4.19 volts. I guess I will trust that the pcb would have worked had the battery dipped below 2.5 v. From reading about copper dissolving in HKJ explanation I guess the battery is just as dangerous in the drawer as it would be in the flashlight. I try to never allow batteries to dip below 3.3 volts so I have little experience with undercharged cells. Apparently once a runaway reaction begins the pcb isn't of any use.
I found this quite interesting
https://youtu.be/sRwoYJyjZNo
https://youtu.be/sRwoYJyjZNo
