Should 18650 Cells Be Charged Regularly to Prevent Power Loss? Car Batteries Comparison

Hello!

One thing puzzles me.
Should 18650 cells be charged from time to time to prevent excessive power loss? I know that car batteries are used on this basis, but it's a bit different.
Alternatively, how do you use these types of cells?

Regards

Sentences are usually divided ... It is often said that leaving these cells fully charged is not indifferent to them (i.e. they lose capacity). Certainly, deep discharge cannot be allowed ...

Optimal storage conditions for 18650 cells - charging level 40-50% at a temperature of 0 - 10 degrees ?. Overcharging and overcharging have a catastrophic effect on the state of the cell. A defense diagram is installed in the cell, which is located inside the body on the side of the positive lead. At 4.25V, the defense diagram blocks charging, and when the voltage drops to 2.75V, it disconnects the cell from the load.

Ture11 wrote:

Sentences are usually divided ...

... and as usual, where three Poles, there are four sentences
Here sentences have nothing to do, and unfortunately often these home-grown opinions are sometimes wrong and harmful.

Manufacturers and their cell catalog cards clearly say how to store cells.
Panasonic recommends a full charge, Samsung 50% temp.

Quote:

... and as usual, where three Poles, there are four sentences

Sentences may be what they want, but accelerated degradation due to prolonged maintenance of high SOC is a fact.
https://www.researchgate.net/publication/3038..._Battery_Degradation_for_Cell_Life_Assessment

Discussions felt such a great need to express their opinion that they overlooked the fact that the author asked about something else

Quote:

Should 18650 cells be charged from time to time to prevent excessive power loss? I know that car batteries are used on this basis, but it's a bit different.

Both in lead and lithium one should not allow self-discharge to "finish" the battery. New LiIon batteries have less self-discharge than lead, they are at a level of a few% per month, but as the battery is used, as well as with temperature, self-discharge increases, and it is worth checking more often in older batteries.
Lead batteries "like" SOC = 100%, so you can recharge at any time and even leave permanently on a buffer charge.

It is a bit different with LiIon, here maintaining the maximum voltage for a long time is harmful, and buffer charging is inadvisable, if the battery is not used for a long time, it is worth checking the voltage, connecting the charger "just in case" is not a good idea.

Quote:

Manufacturers and their cell catalog cards clearly say how to store cells.
Panasonic recommends a full charge, Samsung 50% temp.

First of all: the "18650 link" only determines its size. And how they should be treated depends on its chemistry - here it is not even known whether it is NiMH or lithium (however lithium is more common). At the same time, both NiMH and lithium are of many types, requiring different treatment - and it is quite possible that the lithium of one company will be stored best when fully charged, and the lithium of another company will hurt, and it will be best if it is half charged (and even within one company there may be such differences - batteries are made for different applications, the company can use several varieties of their chemistry, depending on the intended application, to make it better suited to it).

Self-discharge of a few% per month is a lot - although a dozen or so years ago NiCd had bigger ones and NiMH even bigger than NiCd ones (currently new technologies have significantly reduced them, NiMH Eneloop batteries are an example). A good gel battery (or AGM - a slightly different technology, similar properties) can be left for two years after charging and still retain a large part of the charge - i.e. has a self-discharge of less than 4%. A good lithium battery will keep a large portion of the charge for 10 years.

And another thing is that if the battery is left unused for a long time, it is degraded regardless of the charge level - the electrodes are recrystallized. Maybe it depends on the chemistry, maybe they are such that such storage does not matter, I do not know - but for many it is advisable to discharge and recharge them from time to time.

And also about what aksakal wrote in # 3 - it's about the protection circuits built into the battery - this only applies to lithium, and I think that not everyone, you need to check it in the description.

Hello, as I do not want to create a new topic, I would like to ask if having Sony us18650gr cells should I equip them with an external circuit cutting off the receiver's power supply in case of cell voltage below ~ 3V? On one page about a sony link it is written that it should not be allowed to discharge below 2.5V (i.e. what, there is no built-in circuit?), In turn a few posts above @aksakal writes

aksakal wrote:

and when the voltage drops to 2.75V, it disconnects the cell from the load.

So how is it after all? And if I should mount such a system, are there ready solutions on the market or do I have to combine myself?

gandalf_58 wrote:

So how is it after all?

Freddy wrote:

Manufacturers and their cell catalog cards clearly say how to store cells.
Panasonic recommends a full charge, Samsung 50% temp.

gandalf_58 - But you have the answer, just above your question, this is the peak of laziness ...

_jta_ wrote:

After all, you have the answer, just above your question, this is the peak of laziness ...

Today, some need to bring home and give apologies that it took so long. The peak of everything.
It is suitable for the basket

Approx. So I understand that having a link discharged to around 3V the flashlight should not shine for me. In the meantime, I found an old flashlight with such a link, I do not know how long it was, but certainly a year / two, I fired it and lit it, less than usual but still worked. After checking the voltage was ~ 2.4V. So how? Safety system broken?

Thank you all for the answers. I have already learned many things.

"Both in lead and lithium one should not allow self-discharge" to finish "the battery." '

After checking the voltage was ~ 2.4V. So how? Safety system broken?

Or he's not here. It's better to recharge quickly, because such a discharged lithium cell corrodes inside.

But first make sure it's a rechargeable battery, because it is absolutely forbidden to charge disposable lithium cells.