How far can LiIon be discharged?

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HKJ
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Illumenated wrote:
So what do you guys DO with all the batteries you’re not using right that minute? Are they in storage? If so, how do you store lights without letting them drain down too far??

Most lights do not drain the battery when off, this means you can store the battery in the light for years.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

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Illumenated wrote:
… Sorry it’s actually an 18350. Keeppower. I’ve let it run down to empty quite a few times over the last year while camping, using as a night light etc. Guess I’ve been lucky so far. …

Ask Olight tech support what is the minimum operational battery voltage for your flashlight. If 2’5+V, nothing to worry.

Illumenated wrote:

So what do you guys DO with all the batteries you’re not using right that minute? Are they in storage? If so, how do you store lights without letting them drain down too far??

I’ve got a Nitecore charger where I keep my spare 18650 or 18350s charged up so that they are ready to go when my flashlights die. Is that safe?? I believe the charger has a cutoff system that shuts off when they are fully charged

Store batteries where you know no moron would touch them.
Minimize battery stress keeping their no-load voltages well below the specified maximum (I’d say at or below 14/15th of this value) and, of course, not too low. Between 40-50% of SoC (state of charge) is said to be optimal for this purpose, which should correspond to around 3’77-3’85V… but heck, no need to be so anal on this, just aim at around slightly above nominal no-load voltage and you’ll do fine.
My last li-ion battery shipment tested exactly 3’8V on my multimeter.

Storing batteries on a charger is generally unwise, to my knowledge lots of them have some kind of ghost drainage which could kill unprotected batteries if kept for long enough Facepalm (it could be a very looong enough, though).

Advice
At this bargainly price, do yourselves a favour and get one:
DT-830D for 3½ bucks at Aliexpress

Cheers

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JakeDjanitor
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Thank you salvadore. Too had we cant program phones to stop charging at 80% and shut down at 10% rethought monitoring them

Barkuti
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As I said, there’s really no point in preventing your device battery state of charge from falling below 10%, unless you deliberately do so in order to still have some power left in case of emergency.
Device manufacturers know what they’re doing: your stuff’s battery will never get damage no matter how many times it does a forced 0% shutdown. Every bit of this I already explained above.

Cheers fellas Crown

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sixty545
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Illumenated wrote:

Sorry it’s actually an 18350. Keeppower. I’ve let it run down to empty quite a few times over the last year while camping, using as a night light etc. Guess I’ve been lucky so far.

Reading this thread makes me feel like I’ve been a bad father for almost burning my house down due to irresponsible battery parenting.

Keeppower has a protection circuit at the bottom so you cannot harm it by emptying it fully. Just keep on using it as you do.
That is if it is NOT an IMR battery! They do not have the protection.

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Take a look at these:

MOS DIY 26650 Battery Protection Board

4.2V Dual MOS DIY 18650 Battery Protection Board

The 26650 board has 2 additional slots where you could solder additional 8205A’s, for up to, at least, 8A sustained and 12/16A peak current delivery.

Cheers

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tops2
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Illumenated wrote:
Sorry it’s actually an 18350. Keeppower. I’ve let it run down to empty quite a few times over the last year while camping, using as a night light etc. Guess I’ve been lucky so far.

Do you mean 16340 (RCR123) or 18350? I’m using the Olight 16340 in mine and didn’t think 18350 would fit.. Sorry for derailing thread…

I did do one runtime test with the S1 till the protection kicked in. Was tempted to do another runtime test at another level, but then didn’t want to run the battery all the way down again.

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gauss163 wrote:

But you’ll have to charge it 3x as much as would most users, so any benefit in cell lifetime may be offset by wear in other components (e.g. the USB jacks).

One of the main advantages of Li-ion cells over NiMh is the increased energy density. By using less than half (1/3?) of your cells capacity per cycle you are negating most of that advantage. Typically such ultraconservative charging regimens are only employed in devices where it is extremely difficult/expensive to replace the battery (e.g. unmanned spaceships), and/or where ultra-long life (> 6 years) is required (e.g. electric vehicles).

I do not remember to have said I used just ⅓ of my battery capacity. I, generally, charge up to 60% of my maximum battery capacity so, in essence, that means I, at most, charge my device twice as much, all other conditions equal. Battery life expectancy, as said, potentially cuadruplies.
You could still benefit from a good deal of extra life expectancy (nearly 3x) by going up to about 72-74%, maybe.

With regards to the added wear on the USB jacks, I can buy a 10-pack of ‘em for a buck or so (I have around 4 jacks lying somewhere on a bag, tinkerer I am). I am quite dextrous wielding my quality JBC soldering iron, and I have plenty of solder wire, cables and stuff… Steve
Hope this is adequately understood.

Cheers my dears

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Illumenated
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Quote:
Do you mean 16340 (RCR123) or 18350? I’m using the Olight 16340 in mine and didn’t think 18350 would fit.. Sorry for derailing thread…

They are 16340 actually. Sorry for the confusion. Sounds like it’s protected so I’m not as bad of a battery parent as I thought!

Ken Hegemann
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Could someone please present the discharge charts for the following two batteries? 1) NiMH 3 cell, 3.6 volt, 930 mAh capacity and a load of 500 mA. 2) Lithium-ion 3.7 volt cell, 800 mAh capacity and a load of 500 mA. I would like to comapre the voltage of the two batteries as they drain. Thanks

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Ken Hegemann wrote:
Could someone please present the discharge charts for the following two batteries? 1) NiMH 3 cell, 3.6 volt, 930 mAh capacity and a load of 500 mA. 2) Lithium-ion 3.7 volt cell, 800 mAh capacity and a load of 500 mA. I would like to comapre the voltage of the two batteries as they drain. Thanks

Reviewer and tech wizard HKJ may be of help here. His website, https://lygte-info.dk, hosts thousands of battery reviews. Your question is too generic, there are lots of different possible batteries meeting those scant specs. A 930mAh cell could be some Ni-MH AAA, or some rugged long life industrial Ni-MH AA. Various 14500 (AA size) cells meet 800mAh li-ion capacity spec. And there's more.

 

Cheers Smile

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bluereidon
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Guys for Samsung 18650 30Q when do you charge them?3.6 or lower volts?
One more question if you put them out of the flashlights and store them which is the recommended voltage for storing li ions lets say for an year?

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3,6V would be recommended yes.

Actually, 3,4V would be even better since self-discharge is even lower at this voltage.

Just check their voltage every few months just in case.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

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I wouldn’t worry about self-discharge on a cell in storage or in a flashlight with no parasitic drain. I have 50+ 18650’s stored away that were at about 3.6v 5 years ago and some that I pulled last year were still around that.

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If anyone wants to know how far a cell can be discharge and still perform well I recommend reading this entire thread.
http://budgetlightforum.com/node/20513

I read a lot of datasheets with lots of opinion’s on the web and I have personally tested a lot of cells.
The thread above goes against everything I had read or was told. Not to say the datasheets are wrong but no data on what happens if the cell is subjected to outside of those specs. It’s a must read for battery Guru’s. Beer

Thanks for the info HKJ. Thumbs Up

I also still have the batteries in that thread at 10 years old now, I may do a discharge test just to see where they stand.
Anyone else still have some of these?

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bluereidon, charge your batteries when you see fit. I usually do it below ≈3.6V, to always have some juice left.

Li-ion cell over-discharging is something I do not worry about. 2.5V is a frequently used and perfectly safe figure, even 2V for some chemistries. Those numbers can be found in top OEM cell datasheets.

I've recharged cells which were somewhat below 2V, from laptop packs. They can still work after this but I advice to keep them quarantined while whatching their self-discharge rate.

To me, the over-discharge thing is a busted myth, of course thanks to wisdom and discernment. 

What really “hastens” battery/cell degradation is high voltage, and what I mean here is you can noticeably increase the number of useable cycles and life span by reducing the charge voltage. See BU-808: How to Prolong Lithium-based Batteries @ Battery University.

 

Smile 

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mikeyx
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I recently purchased some 18650 cells and when I put them in the charger they were uncharged. Is this ok ? In the past, all cells that I have purchased have had partial charges when I received them.

Thanks,
Mike

WalkIntoTheLight
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mikeyx wrote:
I recently purchased some 18650 cells and when I put them in the charger they were uncharged. Is this ok ? In the past, all cells that I have purchased have had partial charges when I received them.

Did you measure their voltage with a multimeter? What was their exact voltage?

If you’re reading zero volts, check both ends of the battery to see if there’s a thin clear plastic tab on it. Sometimes they put those on to prevent shorting or discharge during shipping. Obviously, they need to be removed.

If they’re protected cells, they’ll also read 0 volts if the low-voltage protection circuit has triggered. They might still be okay after activation.

If you’re reading something between 0 and 1 volt, I personally wouldn’t trust that cell. Under 2 volts, I’d still be a bit nervous of it, depending how long it has sat that low (and you don’t know how long).

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The problem is not how far it works to be discharged, it’s about how far do you afford to do it.

Original Li-Ion spec is very clear: at 3.3V it is considered discharged and at 4.2 it is considered fully charged. Anything out of this interval will inevitably reduce lifetime. They do that to smartphones a lot: they overcharge to up to 4.35V.

Given the manufacturing improvements over the years, yes, the damage taken is smaller but it still happens: the cell will have less life-cycles.

So when choosing how low you want to go with a discharge, you practically establish the life of your cell.

agent80
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Does this mean that for laptops, cellphones and powerbanks, its bad practice to discharge Li-Ons below 10%?

Overmind
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Generally yes.

If you want super extended lifetime for you phone battery you can stop charging at 80% and don’t discharge it all the way. In fact, most phones will try to stop you from discharging completely (have failsafes at around 15%) as getting too low may not provide sufficient current for normal functionality anyway. Some battery-related applications also recommend charging only up to 80% which corresponds in most cases with the 4.2V value.My article about phone batteries here.

On the laptop side things are a little more elaborate. Laptops will not overcharge Li-ion cells as far as I’ve tested until today, but they have another problem: most models except the high end and top ones have low quality or even no charge/discharge BMSs. That will mean in time (taking a 3 cells in series battery as example) that a pair of cells will start not getting enough charge, another will remain balanced and another will overcharge, leading to 2 / 3 cell pairs starting to degrade faster and faster. That is one of the main reasons of current laptop batteries dying so fast.
In the case of laptops I only use them on battery when really needed and I don’t cycle the battery as some do because cycling does lower lifetime compared to not doing it.

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While I agree with many stuff in Overmind's article, I believe differently in certain areas. The discharge cut-off thing, namely.

The industry standard for li-ion cell discharge cut-off nowadays is 2.5V, even though older and/or high voltage energy cells usually set it higher. Examples: Samsung ICR18650-30A/30B/32A specify 2.75V cut-off, LG ICR18650-C2/D1 specify 3.0V cut-off, LG ICR18650-E1 2.75V cut-off, LG INR18650-MJ1 2.75V cut-off…

In essence, the selected cut-off voltage for a cell or battery is, in my opinion, the highest voltage which allows delivery of the battery's minimum specified capacity at its maximum specified discharge rate or current

 

I also take great care of smartphone batteries, being a heavy user of these devices. I run a rooted custom Android ROM and pay great attention to power handling and consumption, clipping the wings of certain apps and uninstalling any unneeded bloat if required. With 3C Battery Monitor I enjoy battery usage graphs, history and even statistics. I do not usually charge above ⅔ of the fuel gauge, but don't hesitate to go all the way down to 0%. Smartphone batteries do have built in BMS circuitry and cut-off properly, no need to care for this. In fact, in all my rooted Android devices I disable the low battery warning (works by disabling System UI notifications). 

 

 

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mikeyx
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The cells that I purchased were new and appeared to have no, or very little charge. I asked the dealer (IMRbatteries) if they were ok and they said to charge as normal. They charged fine, but I don’t like to take chances with li-ion batteries and I value the information from the forum members here more than the dealer. So I will probably discard them.

Thanks,
Mike

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mikeyx li-ion batteries often ship with relatively low voltages, I think this is due to transport regulations.

What cells? What voltage? Multimeter measured, doesn't it?

 

Some of you seem overly dramatic with the low voltage thing, but in my experience it really is a myth. I've salvaged laptop cells with really low voltages, even a few slightly below the 2V threshold, and they ended up working well. After initial discharge tests to verify their performance I further charge them close to 3.9V, measure and write down their resting voltage at least half an hour after this, and them let 'em rest a few weeks. Finally I measure their voltage again and compare to the initial figures. This is a good integrity check as healthy cells will barely show any self-discharge, few millivolts at most. 

 

Wed, 10/02/2019 - 21:29

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I get the feeling mikeyx didn’t measure the voltage with a DMM. Maybe he just relied on what the charger said, but most chargers are horribly inaccurate.

When I buy new cells, the first thing I do is measure their voltage. All good ones arrive at somewhere between 3.3v and 3.6v. They ship at a low charge for safety reasons.

As Barkuti says, then you should probably test them. I do what he does, but instead I fully charge to 4.20v. After a week or so, they should still be above 4.16v. Voltage will drop some initially, which is why they don’t hold a full 4.20v, but after a few hours, they should maintain voltage pretty well. If you use 3.9v as Barkuti does, they should hold rock-solid after the initial drop when you remove them from the charger.

I have many cells in storage at 3.75v, and they hold that way for years.

If you see any cells self-discharging at an unusually high rate, they’re bad.

Also, feel the cells often when you first charge them. They should never get hot. That also indicates they’re bad (assuming you’re not charging at too high a current).

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mikeyx wrote:
The cells that I purchased were new and appeared to have no, or very little charge.
Unless you know what their voltage was at the time, you really cannot judge their state of charge/discharge with any sort of accuracy.

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