BU-802: What Causes Capacity Loss?

Discover what causes a battery to fade.

The energy storage of a battery can be divided into three sections known as the available energy that can instantly be retrieved, the empty zone that can be refilled, and the unusable part, or rock content, that has become inactive as part of use and aging. Figure 1 illustrates these three sections.

Aging battery

Figure 1: Aging battery.

Batteries begin fading from the day they are manufactured. A new battery should deliver 100 percent capacity; most packs in use operate at less.

Courtesy of Cadex

As the rock content portion of the battery grows, the charge time shortens because there is less to fill. Quicker charging times on faded batteries are noticeable especially with nickel-based batteries and in part also with lead acid, but not necessarily with Li-ion. Lower charge transfer capability that inhibits the flow of free electrons prolongs the charge time with aged Li-ion. (See BU-409a: Why do Old Li-ion Batteries Take Long to Charge?)

In most cases, the decrease is linear and capacity fade is mostly a function of cycle count and age. A deep discharge stresses the battery more than a partial discharge. It is therefore better not to discharge the battery fully but charge it more often. A periodic full discharge is only recommended on nickel-based batteries to control “memory” and on smart batteries as part of calibration. Lithium- and nickel-based batteries deliver between 300 and 500 full discharge/charge cycles before the capacity drops below 80 percent.

Specifications of a device are always based on a new battery. This is only a snapshot, which cannot be maintained over any length of time. As with any shiny new machine, the battery will fade and if left unchecked, the reduced runtime can lead to battery-related breakdowns.

A pack should be replaced when the capacity drops to 80 percent; however, the end-of-life threshold can vary according to application, user preference and company policy. Capacity measurement, a service that remains the best indicator for replacement, should be done every 3 months with active fleet batteries. (See BU-909: Battery Test Equipment)

Besides age-related losses, sulfation and grid corrosion are the main killers of lead acid batteries. Sulfation is a thin layer that forms on the negative cell plate if the battery is allowed to dwell in a low state-of-charge. If caught in time, an equalizing charge can reverse the condition. Grid corrosion can be reduced with careful charging and optimization of the float charge. (See BU-403: Charging Lead Acid)

With nickel-based batteries, the rock content is often the result of crystalline formation, also known as “memory.” A full discharge/charge cycle often restores the battery to full service. A periodic full discharge while the battery is in service keeps the crystallization under control and prevents damage to the separator. ( See BU-807: How to Restore Nickel-based Batteries )

The aging process of lithium-ion is cell oxidation, a process that occurs naturally as part of usage and aging, and cannot be reversed. ( See BU-808b: What causes Li-ion to Die )

Last updated 2017-08-16

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Comments (28)

On July 28, 2012 at 9:36pm
ANA KALEL wrote:

I have a laptop intel celeron) FUJITSU SIEM.
- Only two days ago I have a show in the taskbar (red x) on the battery, tells the following message: - consider replacing the battery.
Please How do I know that this message is correct or not, or how can I be sure of remaining battery life.

If that were true, then how and where I can find a new battery for this type of laptop.

On August 13, 2012 at 12:04pm
Timothy Young, Jr. wrote:

Hello. I, too have this problem with my laptop. Additionally, my laptop began slowly “rejecting” my 65W-AC charger, not too long ago, saying it was unfamiliar with it and that my computer would run slowly. After a few days of idleness I return to it today and it tells me I need a 90W-AC adapter or higher for it to charge along with the message that I should consider replacing my battery.

On November 12, 2012 at 3:41pm
fera wrote:

I just bought it a month ago. 3 days after the purchase, its battery capacity to be run out faster, and only takes 2 hours to fully charge. usually it takes 4 hours to fully charge. my battery is 6-cell li-ion

On November 12, 2012 at 3:45pm
fera wrote:

my netbbok is hp mini 110-4112tu

On January 5, 2013 at 9:37am
Italo wrote:

Hello there,

I’ve bought a Macbook Air mid 2012 and using an application called Battery heath I found out that my battery now has only 87% of it’s original capacity.

I had noticed that my Macbook wasnt so much charge as before but 13% in 6 monhs.. is that normal?

Thanks in advance

On January 5, 2013 at 9:41am
Italo wrote:

I forgot to mention.
I have gone through 274 cycles. (average more than one cycler per day). I need my computer or working.

On April 3, 2013 at 2:38am
baburaman wrote:

I would like to add my doubt that will the battery still be delivering rated load current irrespective of Battery charging level?

i.e. when 100% charge level it delivers the load current of 7Amps

what about the rated delivering current when it is 20% of charge level when the connected load remains same.

Please can somebody answer.may my doubt can be chilly but want to know the fact.

On July 31, 2013 at 11:09pm
agua wrote:

i have a dell laptop and while charging the battery it does not detect my charger but when i shut it down and start it again then that is the time the laptop will detect my charger.

what should i do if my battery does not charge when i plugged it in?

On March 3, 2014 at 9:40am
Elvis wrote:

I always search a way to stop draining battery in my SAMSUNG S3 Mini, I use o lot of ways.

Can you help me to change it and to return to normal batteries.

Capacity: 1500 mAh
Voltage: 3.8 V Li-ion (5.70 Wh)


On March 31, 2015 at 2:18pm
Drago wrote:

I have Xperia Z and I tested strange behavior (shutting down on 60%) with official Sony battery test app. And it says that my batter has reduced capacity.

Does this mean that battery with reduced capacity provides less voltage?
Can somebody confirm this?

Thank you in advance!

On April 13, 2015 at 3:48am


I bought a 100Ah led acid battery for inverter. At first the inverter would go for 7 hrs running a 32” plasma TV and 3 energy servers bulbs 20W max. after 3 months the inverter goes for 1,5hrs with the same load. the inverter charger was tested and was ok. it charges the batteries in three stages as recommended. a bought three other batteries and the problem still occurs . What might be killing my batteries.

Please help i’m losing a lot of money on batteries

On July 15, 2015 at 4:08am
hiten wrote:


I have a hp laptop, it tells me your battery is losing its capacity, I wanted to ask about my laptop battery, It is for HP 635.Before it was working well and charging 100% but now even though I charge 100% battery it sitll goes down, But only I could use it for little time and I have to  connect it with my charger. Now days it only works like 1hr without charging when I bought it was used to work 2hrs and something, and it heats up too much. There request for replacement of battery when i on my laptop. 

So what can I do for my battery so it charges well as full 100%. If need to buy new battery than where can I get from 
Thank you

On December 7, 2015 at 6:42am
jamsheer wrote:

please help me
my iPhone 6 battery only get 8 hours of charge if it is in stand by. if i use phone i get the same duration. the battery fully charged and phone is switched off. after one day the battery have full charge. i want ask that if i replace the battery fix the problem, the iPhone had changed its rom .but have the same problem, thanks in advance

On April 5, 2016 at 1:55am
ron wrote:

I have an Acer Laptop Aspire E 14 E5-471-51 LB

The problem is the battery runs out at different charges but never reached the critical battery life which is 10%. My laptop is set to hibernate once the critical battery life is reached. At first it was normal then it hibernates at 48%. After a few days it goes to 36%. Then it goes to 32% Then 17% then now its 28%. I don;t know if it is the battery since it is new so I don’t think so. Or the RAM since it is running on 64-bit yet 2GB RAM??

Please help

On July 2, 2016 at 6:45am
shrikant raje wrote:

Sir, I have a problem with my 12 Volts lead acid bettery. Battery voltage is 13.8 Volts. Specific gravity of almost every cell is above 1.24 barring one cell which shows 1.200. On even small load of about 500 Watts, the battery discharges within a couple of minutes. Although apparantly she seem to be in good condition. Is it she is not holding charge.?
Pls guide me as to how to restore the same.
Shrikant Raje.

On July 5, 2016 at 5:13am
shrikant raje wrote:

Pls let me have comments on my query.

On August 7, 2016 at 5:22am
Ace Diamond wrote:


I bought a fancy UPS not too long ago. One day, the power went out but fortunately the UPS kicked in and saved the ANSYS EMF simulation I was running on my supercomputer. Unfortunately, about a minute after the power went out, my UPS caught on fire.

After I put out the small fire, there was still a lot of smoke in my home. I went outside and realized my neighbor’s home was on fire so there was more smoke outside than inside. He had a TESLA in the garage and apparently the solar flare that shorted our community also shorted his charger. Fortunately, his garage was separate from his house and was not burning as rapidly as his home. The reason why his home was burning faster than moonshine was due to the solar panels that acted as huge antennae to capture the CME from the solar flare on account of the very long lengths of conductive foil that is embedded in solar panels.

Fortunately, our other neighbor had an old VW Golf that ran on used vegetable oil and he had just filled it up the day before at the local McDonalds….and the VW seemed to have survived the solar flare…..so he drove us to get supplies.

By the time we got back, my TELSA neighbor’s garage and solar home had finished producing a huge carbon footprint and were both reduced to a pile of charred rubble. I invited my neighbor to stay at my home. Fortunately, I had a natural gas line that fed an auxiliary GE fuel cell generator operating at 90% efficiency.

On September 15, 2016 at 7:42pm
Etshok wangdhen wrote:

Is it advisible to keep latop charging though is fully charged when programming is running or not. I aam just confused since some of my frens to keep on charging but some told me to plug out as doon as is fully charged.

On November 9, 2016 at 10:52pm
Freddie Chung wrote:

Hi shrikant raje…. What is the capacity (AH) of your 12V batt? Is it a starter battery or deepcycle or VRLA type? At 500W a 12V battery is discharging at 41.6 A. Quite a big load.. Pls correct me if I am wrong

On February 1, 2017 at 11:07pm
Conundrum1947 wrote:

There has been speculation (see https://arxiv.org/ftp/arxiv/papers/1312/1312.6851.pdf) that NiMH capacity fade may be caused by MH formation in part.
If so then it is a trivial thing to test, and would allow old NiMH batteries to be recycled without dismantling or other environmentally unfriendly processes.

It appears that a similar mechanism *might* cause some forms of Li-ion degradation, in this case LiH6 is formed due to impurities in the electrolyte (namely EC) reacting with Li during intercalation which is meta-stable and “jams” up the chemistry.
I am working on a method to reverse this in Li-ion as it has been proven to work on LiFePO4 if the cell hasn’t vented or built up internal pressure.
Verified no capacity loss despite the cell(s) being well below the minimum.

On February 17, 2017 at 4:00am
sivanandan wrote:

before the first use i doesn t charged my device (smart watch) now it is draining fastly and takes 4 hours to charged fully please help me

On February 22, 2017 at 11:21pm

My phone is sony xperia z1.  Recently my phone get shutdown on 52% battery percentage… N it takes less time to fully charged.  When i switch on the phone with 10 or 15 % charge.. It shows 75 % charge.  What is the problem with my battery!?

On July 12, 2017 at 12:53pm
George - Bosch Batteries wrote:

I request BATTERY UNIVERSITY to completely wipe out any content related to desulfators. Just mention them as a passing comment stating that they are a failed solution. We are in 2017!

Localized charging current takes care of sulfation. First of all, sulfation as a problem only occurs when batteries are kept in low SOC.

However, these desulfator merchants claim that every time a battery is recharged, some PbSO4 molecules remain on the plates. But in such a case we just need to give batteries an equalization charge. Nothing more.

Most of battery life (if on standby) is based on temperature and grid corrosion rate. If the application is cyclic, then it depends on temperature, frequency of discharges and DOD.

Sulfation only affects life if the batteries are kept undercharged for periods extending the limits set by battery manufacturers. In that case, rely on your chargers. Not on these desulfators.

No more desulfators, please. They are a bygone technology whose algorithms have already been incorporated in modern charging systems in the form of localized charging current.

On October 1, 2017 at 8:34am
Daniel Nelson wrote:

I wonder how much that is possible to reuse when a Lithium battery becomes dead after long usage. Is it then possible to reuse the lithium raw material in this battery in order to create a new fresh battery. Reason for asking is that I am thinking of all the future dead batteries that will be left overs from future electric cars.

Do we need to mine new lithium raw material or could we reuse the lithium in the dead batteries to create new once. Is it physically possible to reverse the oxidation and reclaim the lithium again?

On December 2, 2017 at 11:14am
Bobby M. wrote:

Is there anything I can do to, add to the, bitteries of
My golf cart, that will extend the useful life of my carts batteries?  I have seem advertisments that say the
Life can be extended indefinitely.

On April 22, 2018 at 3:08am
John wrote:

I bought a Dell Inspiron 5567 that has a 42 hour 3 cell battery and was very surprised to see in 3 months the capacity max had dropped to 34 hours. Given the complexity of replacing a built in battery vs the ones we could just pop out and replace. I just wonder if these built in one are of cheaper quality. Why is it my Apple MacBook had retained much of its capacity a couple years of use and this Dell has managed to lose a significant amount in just a few months? Obviously a difference with something in quality for this to happen. Could it be the components charging the battery that are of poor quality or are causing battery failures?

On August 6, 2018 at 1:52am
Bert wrote:

For my master’s thesis I’m doing reseach on the economic benefits and costs of V2G, and of course this involves the impact V2G has on the battery longivity.

I am currently looking for information on the impact of the SoC region of cycling on the battery lifetime, but struggle to find any comprehensice literature, and was wondering if anyone could help me with this.
Are there any interesting studies done in this field, preferably on EV batteries, but lab tests on other Li-based batteries would also be very interesting as well.

On August 26, 2018 at 6:12am
mike wrote:

My battery is at 80% capacity, yet I still get 5 hours of run time. Why would I throw that away?