BU-415: How to Charge and When to Charge?

Explore what conditions are best when charging any battery.

Early batteries were reserved for commercial use only, such as telecommunications, signaling, portable lighting and war activities. Today, batteries have become a steady travel companion of the public at large to reach a friend, they allow working outside the confines of four walls, provide entertainment when time permits and enable personal transportation. Best of all, batteries help in missions when people are in need.

Folks are eager to learn more about this wonderful portable energy device and one of the most common questions asked is, “What can I do to prolong the life of my battery?”  Table 1 addresses how to care for your batteries to meet their needs. Because of similarities within the different battery families, the table addresses the needs and wants of only the most common systems by keeping in mind that these desires extend to almost all batteries in use.
 

 



Frequently
asked question

Lead acid
(Sealed, flooded)

Nickel-based
(NiCd and NiMH)

Lithium-ion
(Li-ion, polymer)

How should I prepare a new battery?

Battery comes fully charged. Apply topping charge

Charge 14–16h. Priming may be needed to format

Apply a topping before use. No priming needed

Can I damage
a battery with incorrect use?

Yes, do not store partially charged, keep fully charged

Battery is robust and the performance will improve with use

Keep partially charged. Low charge can turn off protection circuit

Do I need to apply a full charge?

Yes, partial charge causes sulfation,

Partial charge is fine

Partial charge better than a full charge

Can I disrupt the charge cycle?

Yes, partial charge causes no harm

Repeat charges can cause heat buildup

Partial charge
causes no harm

Should I use up
all battery energy before charging?

No, deep discharge wears battery down. Charge more often

Apply scheduled discharges only to prevent memory

Deep discharge wears the battery down

Do I have to worry about “memory”?

No, there is no memory

Discharge NiCd every 1–3 months

No memory

How do I calibrate a “smart” battery?

Not applicable

Apply discharge/charge when the fuel gauge gets inaccurate. Repeat every 1–3 months

Can I charge with the device on?

Avoid load if possible

Parasitic load can alter full-charge detection and overcharge battery or cause mini-cycles

Do I remove the battery when full?

Charger switches to float charge

Remove after a few days in charger

Not necessary; charger turns off

How do I store
my battery?

Keep cells above 2.10V; charge
every 6 months

Store in cool place; can be stored fully discharged

Store in cool place partially charged

Does battery heat up on charge?

Lukewarm towards end of charge

Warm but must cool down when ready

Must stay cool or slightly warm

How do I charge when cold?

Slow charge (0.1): 0–45°C  (32–113°F)
Fast charge (0.5–1C): 5–45°C (41–113°F)

Do not charge
below freezing

Can I charge at hot temperatures?

Lower threshold by 3mV/°C above 25°C

Battery will not fully charge when hot

Do not charge
above 50°C (122°F)

What should I know about chargers?

Charger should float at 2.25–2.30V/cell when ready

Battery should not get too hot; should include temp sensor

Battery must stay cool; no trickle charge when ready

Table 1: Best charging methods. Strenuous demands cannot always be prevented.

Last updated 2016-02-25


*** Please Read Regarding Comments ***

Comments are intended for "commenting," an open discussion amongst site visitors. Battery University monitors the comments and understands the importance of expressing perspectives and opinions in a shared forum. However, all communication must be done with the use of appropriate language and the avoidance of spam and discrimination.

If you have a question, require further information, have a suggestion or would like to report an error, use the "contact us" form or email us at: BatteryU@cadex.com. While we make all efforts to answer your questions accurately, we cannot guarantee results. Neither can we take responsibility for any damages or injuries that may result as a consequence of the information provided. Please accept our advice as a free public support rather than an engineering or professional service.

Or Jump To A Different Article

Basics You Should Know
The Battery and You
Batteries as Power Source

Comments

On January 6, 2011 at 11:52pm
antonyananth wrote:

tnx sir

On January 15, 2011 at 3:36am
arpit wrote:

gr8 article

On January 15, 2011 at 3:36am
arpit wrote:

gr8

On January 19, 2011 at 2:31pm
Glyn wrote:

Very useful and informative - keep up the good work

On February 8, 2011 at 7:39pm
john wrote:

Is there a problem if 5 batteries in different stages of remaining capacity are charged together with one charger?

On March 25, 2011 at 7:04pm
Francisco Bolivar wrote:

I have an elerctric bike with a 600w - 36v motor.
It uses a li-Ion battery.
Usually each time I use the bike its charge drops about 20% of the total battery charge.
WHAT IS BETTER DO DO:
1 - CHARGE THE BATTERY EACH TIME I USE THE BYKE (battery with 80% of charge)
2 - CHARGE THE BATTERY ONLY WHEN IT HAS 60% OR 40% OF CHARGE

On April 18, 2011 at 1:23am
Sameer Wagh wrote:

Good articles , but I have one question…..

If we add batterties in Parallel to increase capacity , how much capacity chargers are required. i.e. do we need to add the Ahr. capacity of all batteries to determine the capacity of charger?

If we add batteries in series to increase voltage requirements , do we need to increase the capacity of charger.

Rgds

On June 8, 2011 at 1:42am
Lazaros wrote:

My original charger is at 700 mAh. Could I use another at 1500 mAh or it would deteriorate my phone battery?

On July 4, 2011 at 10:37pm
Jerome Girard wrote:

Simple, precise, thanks a lot!

On July 18, 2011 at 3:39pm
rich chapman wrote:

I’ve got one- Why do instructions for many battery cell chargers say to first put the battery in the bay and then to plug the unit in?  Does it not charge correctly if you put a battery in the bay when its already plugged in?

On August 26, 2011 at 5:49pm
fastman wrote:

Thanks ...this article is very useful ..I am going to buy a new laptop tomorrow with lithium battery and I will not fully cahrge it the first time as i thought

On October 5, 2011 at 2:35pm
Ramakanth Viswanatha wrote:

can i use a dynamo ( for example a dynamo in a cycle to lighten the head light ) in a byke rear wheel . So, that while running the byke the dynamo works and through wiring the dynamo is connected to a rechargeable battery and so the battery is charged and there is no issue of charging drop rate….This was my assumption .

On October 13, 2011 at 10:59pm
jacob wrote:

What is the recommended charging time for the first charge of a lithium ion battery for a new cell phone? I should charge it before I turn my phone on, correct? Its a 1500halloween mah, 3.7v. Any help would be appreciated. Good articles here.

On November 22, 2011 at 7:09am
zachary wrote:

how long do you charge a 12v Lead acid
(Sealed, flooded) battery?

On December 1, 2011 at 8:07am
mahesh wrote:

sir i have a huiandai tubler bettary for my invertor it is 60% damage but company can not change it. in what type i can dead fully damage my bettary

On January 9, 2012 at 10:04pm
Himani wrote:

Informative article !

On January 22, 2012 at 12:01pm
Junedul wrote:

my batteries alithium ion

i bought it new as a replacement and have been charging it for 3 day

i turned it on and it was at 75% and said critical

i turned the adapter off and the laptop lasted a minute, have i damaged the new battery
and why is it stuck on 75%
thanx

On January 23, 2012 at 5:31am
Mercy Ejindu wrote:

my phone battery is charging on it own with the power what should i do

On February 25, 2012 at 11:48am
Craig wrote:

Lithium Ion batteries, can I check voltage to determine if they are fully charged?  They are for portable radios at 7.4 volts.

Thanks in advance for your help.


Warm regards,

Craig

On March 16, 2012 at 1:14pm
Tina wrote:

what does topping mean?

On March 26, 2012 at 3:31am
Ali wrote:

tnx for your gr8 article
I had a question about li-on batteries
Is it right that some people say
charge your battery only when it is on 40% or 60% of charge
and cut off the battery from charger when it reached the 80%?
plz answer me!

On June 20, 2012 at 7:26am
James Japp wrote:

“Discharge NiCd every 1-3 months”

Does this mean that I should be discharging even those batteries that I don’t use very often. In some torches it would take me half a year, if not more, to fully discharge battery by normal use. Should I intentionally drain those batteries every 3 months?

On September 24, 2012 at 7:16am
omar wrote:

when the battery is completly charged is there any damage on it when i keep the charge on and is it disconnect when it fully charged ??

On October 12, 2012 at 12:51am
Jose wrote:

I just bought a tablet and i just like to know if it is okay to leave it plugged in while it is docked after it has charged to full while using it…

On November 19, 2012 at 10:03am
Mário wrote:

This topic it has been very helpful to me, I’ve 4 12v 100 amp batteries, in a 12 volts battery bank. I want to charge them as quickly as is possible without damaging them from 220v a/c source, Whats the technical specifications that i should look for in a charger. A model would be a great help but as I live in Africa it can be difficult to find.

On November 24, 2012 at 9:22am
Davey Dee wrote:

Strange that the author here does not reply, for those needing help.

On November 28, 2012 at 7:11am
Jaka wrote:

You are the best! It is really helpful instruction.

On January 9, 2013 at 8:33am
SOUISSI wrote:

Des cours tres instructis un grand merci a tous .l’echange du savoir humain merite notre reconnaissance car un jour l’humanite en y puisera son salut.

On January 12, 2013 at 6:42am
jayasuriya nandhagopal wrote:

its a owesome site which i have seen. i like tis one .i got useful informations in tis site

On September 9, 2013 at 7:33am
Solomon wrote:

a useful message

On November 23, 2013 at 6:37am
Megha wrote:

not fare enough…

On December 11, 2013 at 10:51pm
BERGE JERMAKIAN KC2SBO wrote:

All batteries when not in use self discharge. The type determines the rate of discharge. In the case of lead-acid batteries not being used for any period of time should be put on a charge maintainer. Keep in mind that weak or discharged lead acid batteries can freeze if left in prolonged freezing temperatures, which can render them useless. Ni Cads discharge fairly rapidly. Keeping them in a cold location will slow down the self discharging. Lithium batteries have a very long shelf life at normal room temperature.

On December 22, 2013 at 11:58pm
muhammad Bilal wrote:

what are the principles work behind the cahrging of a battery?? can anybody help me

On March 21, 2014 at 6:55am
Nigel Ndlovu wrote:

My battery has not been charged for two weeks and it seems to have a problem cause i put the charger on and its still 0% full . What can I do

On June 17, 2014 at 6:14pm
Angelo wrote:

Half the battery pros say plug in the charger first then plug the charger into your battery. Other so called battery pros say plug into your battery first then plug into the charger then plug the charger in. Which is it?

On June 19, 2014 at 6:11am
Azlan Aziz wrote:

Informative article & very helpful..
Thank you.

On June 23, 2014 at 10:40pm
volker wrote:

there’s following setup given:
cheep model helicopter with a single LiPo cell (3,7V, 1000mAh)
and a simple “charger” Vout= 4V, 500mAh.
charger seems not to have any charging-electronic.

Possible to coverload the battery with this “charger”?

On June 24, 2014 at 1:00am
Volker wrote:

@Angelo:
this seems to depend on the charger. I know that e.g. for all Jun-si iChargers (chargers for rc model) first method is the correct method (First plug the charger to powersupply , then plug battery to charger)
and 2nd method can damage the charger.

For other chargers may be you can choose either method.

On June 27, 2014 at 3:44am
Narcais wrote:

I have a problem with my phone:
In normal charging the phone battery is not charging more than 51%. I tried several types of chargers and is the same problem (battery charger is not the problem).
On an external charger battery charging normal 100%....
Which is the problem?

On August 6, 2014 at 9:50am
sumit wrote:

I just bought a moto G How do I first charge it to increase battery life. pleeaase help

On August 13, 2014 at 6:53am
V.H.SHAJI wrote:

SIR,
I have one touchmate MID 790 tablet which is new and one year old,not working so far,
Now I charged with power,the charge not existing at all.What is the reason,and remedy also.Please advice me to my email.

On October 23, 2014 at 6:40am
Aruna wrote:

does the amount of input voltage equals to each of the output voltage

On October 25, 2014 at 2:59pm
Angelo wrote:

Volker thanks for your response. Your right. I researched firther and it all depends on the charger.

On November 18, 2014 at 10:51am
Filippo wrote:

I have a samsung galaxy s3 or anyway smartphones in general

could you tell me which range of charge is better for the life of a lithium ion battery?

something between 20 and 85%  ? I guess

On January 15, 2015 at 8:16pm
Vidya wrote:

can i use the sony rechargeable batteries in kodak charger?

On January 31, 2015 at 7:42pm
Daniel Rawinsky wrote:

I would like to know more about locomotive batteries. We have a 1943 Alco RS1 which runs on 8ea 8v batteries. We have been trying to keep the batteries charged but since the alternator for keeping the batteries charged (as compared to the alternator to power the traction motors) is not working. We have found some dead cells and these batteries are expensive and very heavy. What kind of battery would be suitable to replace the dead batteries?
Thank you
Daniel Rawinsky

On April 7, 2015 at 2:17am
Edward wrote:

Daniel, You can use the cylindrical 18650 Li-thium battery pack to replace the all battery packs

On April 15, 2015 at 4:03am
issy_i wrote:

Hi guys i noticed when the battery is charged fully it drops really fast from 100% to 98% within a minute.. (doing nothing exept turning on screen) Then it keeps dropping “fast” to about 75% But then it stablize.. Very weird. Im satisfied with the battery life becouse most of the time i get 4 hrs Screen on time…... Just noticed the fast discharge from 100% +- to 75%
Is this normal?

Using the Sony Xperia z3 compact (li-ion batt)

Also when fully charged 100% it shows 4,25mV… I thought everything above 4,2mV is bad?
(you can chech this by dialing *#*#4636#*#*

On May 14, 2015 at 10:30pm
Michael wrote:

I have a 6v 4.5ah 20hr Lead Acid Sealed Battery used in a toy bicycle. It comes with a charger 6v 500mA.

a) How long should i charge the battery? - I read it should automatically switch to float charge so does this mean i can charge it as long as i want - even days, months?

b) How will i know when it is actually fully charged? - Can i use a multimeter to check? I dont have one but I can go out and buy a multimeter - but i dont know how to use it. Pls give me step by step instructions.

 

On June 27, 2015 at 1:55pm
Christian wrote:

Pls what should I use to charge my new phone battery so that it will last for 24hs

On July 4, 2015 at 12:02pm
Christiaan Ghijselinck wrote:

Specific questions about LiFePO4 battery cells :

The nominal voltage is 3.20.V.  Does this means that its SoC is 100 % ?  What is the cell voltage ( without load ) at a SoC of 80 %.
What is the SoC in % when the cell voltage has dropped to 2.95 Volt without load

The nominal cell voltage is 3.20V , charging to 3.65V allowed. May damages occur
when a charger keeps charging a cell at 3.30 Volt for a longer period of time , even if
the cell is fully charged ( charge current has dropped to its minimum )

On July 31, 2015 at 11:56am
Franky wrote:

Really helpful!
Thank you!

On August 19, 2015 at 3:50pm
Tommo wrote:

Majestic!!!

On September 8, 2015 at 6:04am
dhivya wrote:

i got my new battery and my mobile is old mobile
i charged my battery for 5 mins and still my phone does’nt on
i need to know whether it is a mistake of my phone or battery
could you help me

On September 29, 2015 at 6:04am
sr wrote:

I only kept my phone for 100% charging only about 1 hour on the first use. And now the 2900mah li-ion battery is discharging very fastly . How can I solve it?

On October 21, 2015 at 9:44pm
Matichu San Miguel wrote:

Apply a topping before use. No priming needed
What do you mean by this?

On November 28, 2015 at 11:39am
Dom wrote:

My Xperia switched on the first time I charged it a few days ago. Possibly I pressed the power without realising (but I thought not). I let it charge switched on like that. Will that have significantly shortened the battery life/capacity?

On December 3, 2015 at 7:10am
awoke computer and related goods shop wrote:

How can i charge my battry using dc voltage ?

On December 10, 2015 at 4:44am
naveed wrote:

tel me plz charging cut off volte narada jel batry (mpg) series. 13.75v or 14v or 14.20v.plzzzzzzzzzz
AGM cut off voltag?????
AGM meaning.?

On December 23, 2015 at 1:11am
jb wrote:

Once again this article repeats the warning against charging while the device is on.

This probably applies only to older/cheaper devices where the connection between device and battery is dumb, and the external charger charges the battery directly regardless if the device is on or off.

On modern high end devices such as phones and laptops there is dedicated battery management circuits inside the device and the charging process is not confused by the device being on during charging.  Some models don’t even charge unless part of the main device is powered on to run battery management software that keeps track of the charging process and does the needed switching between phase 1, 2, 3 and stop states.

On January 23, 2016 at 12:16pm
priyanka wrote:

Sir
   
I want to know about mobile battery and how should i prepare it.I want to do a project on it.so please suggest me sir

On January 24, 2016 at 10:38am
Nick wrote:

“Apply a topping before use. No priming needed”
What do you mean ?

On February 18, 2016 at 12:09am
Bill wrote:

“Apply a topping before use. No priming needed”

What is meant by this instruction ???

On March 7, 2016 at 9:50am
fe wrote:

Hello i just bought a mobile phone and i dont know how much time i have to charge it the first time?thanks

On March 13, 2016 at 8:42am
p.jagapathi babu wrote:

Tell me sir

Types of batterys

What is trickel charging and how to recharge the batterys

On March 15, 2016 at 5:24pm
joni wrote:

Sir ...I have invented a new battery of the mobile phone do not have any charge…
So plz tell me how to share this technology in mobile company

On March 16, 2016 at 8:38am
bugembe wrote:

for how long am i supposed to charge my new samsung side kick battery

On March 29, 2016 at 8:16pm
Maju Mohan wrote:

Thank you for sharing this great information

On April 7, 2016 at 4:29am
Dennis Buffrey wrote:

Sorry to be stupid but I am trying to charge my 6v battery for my lawmower. The battery has clear positive and negative signs on it but the charger has only red and black leads. Can anyone please tell me which is which?

On April 14, 2016 at 5:22am
Mi Breslin wrote:

Great info. But….

Do I need to apply a full charge? Yes, partial charge causes sulfation,

Can I disrupt the charge cycle? Yes, partial charge causes no harm

Can you clarify this?

On April 23, 2016 at 5:33am
BatteryBhai wrote:

Nice Post, charge battery when it requires. Charge battery with battery charger and don’t use any other trick till not necessary.

On April 27, 2016 at 3:15pm
Brian Griffin wrote:

Hi. I Purchased a set of Trojan T1275 batteries for my golf cart and was expecting to get 4 to 5 years out of them but they started showing signs of failing after 2 and a half and by their 3 year anniversary were not able to perform for more than 9 holes. The suppliers took them away and tried whatever recovery process they could but finally returned them saying they were slightly improved but the recovery process didn’t have much effect.They of course blamed the charging process, postulating that they weren’t receiving a full charge and that had hastened the sulfation process (which I understand would be the case.) So I am about to fit a brand new set of T1275. I also replaced the on board computer on the cart itself. How can I check that the batteries are receiving a full charge? It’s far too expensive to be replacing these batteries every couple of years.

I live on a golf course and play 2 - 4 times a week so the batteries do get a bit of a workout. I do try to follow a regular maintenance routine.

Any information and/or suggestions are most welcome.

On June 2, 2016 at 1:57am
John Carass wrote:

My phone is currently in a leatherette case about 2mm thick, is this bad?

On June 16, 2016 at 6:50am
Satheesh wrote:

Can I charge lax20 battery with external car battery

On July 3, 2016 at 3:30am
John o'Connell wrote:

What should be the final voltage reading of a fully charged 36v 3000mAHr Li-ion battery?