Battery question

[ArthurDent]

I have several batteries for my D500. In order to maximize battery life, should batteries not being used be stored charged or discharged or somewhere in-between? Also, does it affect battery life if I use a battery until it is fully discharged, or should I replace it with a fresh battery when it reaches a certain level of discharge. If the latter, at what level should the battery be taken out of service? Thanks for any insights

[pluton]

If I had to choose between storing them fully charged or fully discharged, I'd pick fully charged based on my own limited experience.
Thom Hogan's long-term battery storage advice, written about 10 years ago, is to store Nikon LiIon batteries at roughly about 1/3 charge.  When I got Nikon D3 cameras in 2008, I followed that advice.  After about 4 years, I began to notice a decline in the capacity of those batteries.  The D3 batteries were still working (at reduced capacity) at 4.5 years. 
The EN-EL15 batteries for my D800s have gotten the same treatment, and have lasted similarly.
On the other hand, with my Fujifilm XE- camera batteries, I generally use them in the camera until they are almost completely discharged**, then immediately recharge them.  Then they sit, fully charged, for a week or two (or more) until they get used.  The Fuji batteries have also lasted over 4 years, with only a nominal decline in capacity.
Conclusion: Either way works.
**The reason that the Fuji batteries are used until they are fully drained is that the battery meter in the Fuji cameras has only 4 segments, Full, 2/3, 1/3, and Dead.

[ArthurDent]

Keith- Thank you for your reply. Based on your response, I have amended my question.

[Seapy]

The Li-Ion technology isn't like most other battery technologies. Pluton used the term 'Dead' instead of empty or fully discharged... Big difference, if it's dead then it will never charge again.

The voltage range which is acceptable between fully charged and fully discharged is critical and is controlled by the circuitry within the Nikon battery casing.  This explains why Li-Ion batteries cut out without a noticeable drop in performance, one minute almost full power, next it can cut out.  If the voltage were not finely controlled, especially at the lower range the battery can become unstable chemically.  For this reason it's unwise to store Li-Ion batteries in a low charged state, even (especially?) newish good ones.

The batteries are perfectly happy being fully charged then recharged from any state of discharge.  If the critical low voltage in an individual cell drops below the preset minimum then that battery will not charge again and will effectively become dead.  It is dangerous to charge an Li-Ion battery which is below the critical voltage.  This can result in serious expansion of the cell, fire or explosion.

If a battery becomes fully discharged then it's wise to re-charge it at least partially.  If they haven't been charged recently, that is in the last few days, I tend to top up my batteries before leaving for a photo session because I find especially in winter it helps to get maximum exposures per battery.

Recently some camera batteries have been upgraded and are produced in 'a' variants of older numbers.  So far as I can tell this is because the cell capacity has been increased slightly by the cell manufacturers (not Nikon) by using better materials to separate the chemicals in the battery so less inter cell leakage occurs and thinner so more chemicals can be got into the same space.

NB. I am by no means an expert but I researched the above while re-celling my D3 battery.

[pluton]

The Li-Ion technology isn't like most other battery technologies. Pluton used the term 'Dead' instead of empty or fully discharged... Big difference, if it's dead then it will never charge again.

Robert, Your info comports with all I have read and experienced;  I used the term 'dead' to mean 'the state at which the camera will shut off and not operate' but also to emphasize the poor definition of the Fujifilm battery meter.

[Akira]

I believe that today's battery control system of Li-ion battery pack and the camera is sophisticated enough for the easier handling.

So, I just see to it that the battery is neither fully charged or discharged (according to the camera's indicator) when I need to store the battery for an extended time.

[David H. Hartman]

The best information come from Battery University.

For lithium ion batteries

*Avoid deep discharge when not necessary. Best practice: discharge to about 50 %.
*Store batteries out of camera at 40-50% charge (50-60% discharge). Batteries stored in a camera can go totally dead and become unchargable. I've done that once.
* Start and stop charging at any time. There is no penalty for partial charges.
*

More to follow...

[arthurking83]

Note sure where this info re keeping batteries charged to below capacity comes from, but in my experience it's never worked.
I charge my batteries up and if storing them(eg. old D70s or D300) long term, they've never given grief in terms of explosions, lack of capacity, and other such ill effects.

Deep discharges shouldn't affect a LiIon battery in a way that it shortens their life. Dying batteries will die, no matter how well, or badly, you treat them.
I regularly use AA sized LiIon batteries(14400's) and have a set of a dozen or so.
In the time I've been using them, I've had two of them die(as in can no longer accept charge).
They didn't explode, swell up, catch fire or any other life threatening misadventure! .. they just won't accept charge, even tho I am able to force it into them.
When I put them in my charger, their low state of charge confuses the charger and it thinks they are NiMH batteries(being just over 1.2v), so I jump start them with another battery(connected in parallel to the charge port), the charger temporarily sees the higher voltage, begins the LiIon charge process, I remove the jumper battery and charge continues onwards for a LiIon battery.

Of the dozen 14400's I use, only two of them have failed(prematurely), they all get treated the same way, with a full charge(according to the charger), then discharged to the point where the powered device stops working(ie. full discharged state of the battery).
Just a fact of manufacturing life that some things fail eventually ... or prematurely.

The 4 (14400) LiIon batteries I have as backups have been stored in a charged state for about 3 months now(unused) and are still 'fully charged'.

Note that 14400 are AA sized, and I use them in devices that can accept the (roughly)4 volts capacity in devices that use AA batteries .. predominantly motorised devices.
Those 14400 cells are not too dissimilar to the cells used in ENEL15 sized batteries(ENEL3's etc). Don't have an ENEL4's or 5's to open up to compare, but your average D70s - D850 that uses those similarly sized batteries use a cell type known as 18490 which is a thicker version of the 14400 cell.
I've thought of trying to rebuild the one ENEL15 I've pulled apart with new cells, but those 18490 cells are hard to come by, or expensive, and by the time I've ripped the case apart .. well it's just not worth the effort .. simpler and cheaper to simply get a new aftermarket ENEL15.

[pluton]

I thought I'd add another point of view to this discussion:  Nikon's D800/E User's Manual, page 403:

[Ann]

There seems to be a major contradiction in this paragraph:

Remove the battery from the camera or charger when not in use and
replace the terminal cover. These devices draw minute amounts of
charge even when off and could draw the battery down to the point that
it will no longer function.

Then:

If the battery will not be used for some time,
insert it in the camera and run it flat before removing it from the camera
for storage.

When you buy a new camera or a new battery, the Battery is always shipped with about a 33% charge — they are never sent out flat.

My own practice is to fully re-charge my batteries immediately when I drive them flat or they are showing only about a third charge; and to keep an eye on those spare batteries for older cameras which I seldom use so that they also get recharged before they go flat.

I never store any of my batteries in an uncharged state

I still have a couple of batteries which are eight years old and they still accept a charge. However, all of my batteries are the heftier ones for the D# cameras and the smaller ones may not last quite so long.

[pluton]

I agree:  fully charging camera batteries after use, and storing them fully charged seems to do no harm.
The only explanation I can reason is that Nikon is trying to cover themselves against legal liability in case of fire, the theory being that a flat LiIon battery is less likely to be able to go into the condition of thermal runaway.

[Hugh_3170]

Keith, I also agree about storing batteries fully charged.

The other thing I do is to number like batteries and then use them in strict rotation so that they are "aged" / "worn out" evenly.

[pluton]

The other thing I do is to number like batteries and then use them in strict rotation so that they are "aged" / "worn out" evenly.

This ^^^
It can be hard to manage when one has multiple cameras using the same set of batteries, but worth making the effort in any case.