Charging Battery

Hello, First we need to know the battery chemistry, second the battery voltage.

The battery chemistry determines the charge rate to recharge the battery.

The faster a battery is charged the more heat is generated which can cause major failures from boiling out the electrolytes to explosions and fire. Not good.

Conversely the slower rates generally give a better full capacity charge.

And some types of battery chemistry should be discharged before recharging or they loose capacity to a full charge.

if it is an ordinary cellphone battery,what is ur comment?

Ok cell phone battery. Is it lithium-ion, Nickle-cadmium, Nickle-metal hydride? Most cell phones have there charger built into the phone. The "charger","wall wart" simply supply the necessary voltage/current to the phone to charge the battery.

Some batteries now have sensors/electronics/fuse built in to them to limit misuse or problems in charging/discharging. Also with "smart batteries" the electronics and battery "talk" to each other.

Are you wanting to recharge the battery with some sort of external power source. At minimum you would either have a constant voltage or current. A way to monitor the charging or risk problems.

lithium ion battery

you said that,if battery is charged faster,there Will be risk of boiling out of electrolytes.

What about if the battery is discharged very fast ?

Yes some battery chemistry will overheat and can cause a fire. Li-ion is one of the battery chemistry you would not want to short the output terminals.

you said that,if battery is charged faster,there wil be risk of boiling out of electrolytes,

what do u mean by "rate" denoted here?.....

can u please explain that statement briefly ?

Charging and Discharging Rates

A common way of specifying battery capacity is to provide the battery capacity as a function of the time in which it takes to fully disscharge the battery (note that in practice the battery often cannot be fully discharged). The notation to specify battery capacity in this way is written as C_x, where x is the time in hours that it takes to discharge the battery. In the above table, C₁₀ = xxx (also written as C10 = xxx) means that the battery capacity is xxx when the battery is discharged in 10 hours. When the discharging rate is halved (and the time it takes to discharge the battery is doubled to 20 hours), the battery capacity rises to xxx. The discharge rate when discharging the battery in 10 hours is found by dividing the capacity by the time. Therefore, C/10 is the charge rate. This may also be written as 0.1C. Consequently, a specification of C₂₀/10 (also written as 0.1C₂₀) is the charge rate obtained when the battery capacity (measured when the battery is discharged in 20 hours) is discharged in 10 hours. Such relatively complicated notations may result when higher or lower charging rates are used for short periods of time.

The charging rate, in Amps, is given in the amount of charge added the battery per unit time (i.e., Coulombs/sec, which is the unit of Amps). The charging/discharge rate maybe specified directly by giving the current - for example, a battery may be charged/discharged at 10 A. However, it is more common to specify the charging/discharging rate by determining the amount of time it takes to fully discharge the battery. In this case, the discharge rate is given by the battery capacity (in Ah) divided by the number of hours it takes to charge/discharge the battery. For example, a battery capacity of 500 Ah that is theoretically discharged to its cut-off voltage in 20 hours will have a discharge rate of 500 Ah/20 h = 25 A. Furthermore, if the battery is a 12V battery, then the power being delivered to the load is 25A x 12 V = 300W (about the power drawn by xxx). Note that the battery is only "theoretically" discharged to its maximum level as most practical batteries cannot be fully discharged without either damaging the battery or reducing is lifetime.

from PVCDROM

Hi,

To add to this, like in deep cycle backup batteries, the amount of discharge can be preset to a particular cutoff level. This is called the Depth of Discharge (DOD) normally set to a percentage of total battery capacity. This can be set to value like 60%, 50% etc which implies that once such level of discharge is reached, the system will cutoff the battery supply to the load. This will ensure that close to the designed battery life cycle is achieved, under stated operational conditions anyway.

In this type of operation, during recharge, the charge current is mostly set to 0.1C of the battery capacity and will take about 1.25 times the total discharge time to fully recharge the battery.

As a power back up for hand held devices to big applications, batteries are used for back up. It is a combination of one or more electrochemical cells and they convert chemical energy into electrical energy.

Battery Working:

Lots of voltaic cells are composed together into a battery device. There are two half voltaic cells with a series connection with a conductive electrolyte capturing anions and cations. Electrolyte and the electrode to which anions move in other words negative electrode or an anode is contained in one half cell. And in the other half cell contains electrode and the electrolyte which attracts cations called as the cathode or positive electrode.

At the cathode, reduction occurs to cations in the redox reaction that charges the battery and oxidation occurs at anode. There is no physical connection between the electrodes and the only mode of connection is through the electrolyte. There are different electrolytes for each half cells.

An electromagnetic force EMF for each half cell is given by the capacity of the electric current to be drawn. The difference between the emf of the half cells is called the net emf of the cell. If electrodes have particular emf, the difference between the reduction potentials of the half-reactions is called the net emf.

Battery Maintenance:

For having a good battery condition, equalization of battery is required. As time passes by there is no charging of cells done in a routine fashion as some of them charge slowly and some of them charge very fast. Overcharging the battery for charging the weaker cells completely is called marginal equalization. Charged battery has a terminal voltage of 12 V and automobile battery shows 13.8 V and a tubular battery will show 14.8 V. For avoiding shaking, automobile batteries needs to be firmly fixed.

2 Types of Batteries

1) Primary Batteries:

It is a one time use battery or in other words use and throw battery as per the name. After the discharge of these batteries it cannot be recharged and bring its components to its original forms. It is not advised to recharge the primary cells . Some examples of the batteries are AA, AAA batteries and they are normally used in remote controls, torches, walk clocks etc. They are also called as disposable batteries.

2) Secondary Batteries:

Standard rechargeable batteries also known as Secondary Batteries are those which are reusable after getting discharged by charging it back using electric power. They are composed of active materials in the active state of discharge. Electric currents are applied for recharging the batteries with the use of charger. There are some examples of secondary batteries like the one used in mp3 players, mobile phones, Ipod etc. Miniature cells are used in wristwatches and hearing aids and large batteries are used in computer data centers and telephone exchanges.

There are Various types of Secondary Batteries:

SMF Battery: reliable, consistent, low maintenance

Lithium Battery: for portable devices like laptop, cell phone

Lead Acid Battery: for inverters, automobiles, power systems

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The total recharge/discharge cycle is not 100% efficient. I don't know the precise numbers, but you would need something like 3000-3500mAh to recharge the battery.

Hi, I heard the best way to charge a battery is by constant current mode, so the voltage is always adjusted on the way to 100% charged. But I also don't have clear figures correspond to the type of the cell.

A simple constant volt source isn't give the best results~, is that true?

thanks for sharing~

If you charge with constant current, the charging voltage rises all the time. This is a very dangerous way to charge a Li cell. the safe way to charge a Li cell is to start with constant current and change to constant voltage as the charge nears completion.

That is the general misconception about batteries. 2500mAH is the total amount of charge that can be stored in the battery you are talking about, Now if you remove all the stored charge of battery in each cycle, means potential on terminals will go down to zero.And that is deep discharge, Which is never recommended.

For example in the case of a lead acid battery discharge should not go below 9.5 Volts for the healthy life of batteries. So if you are drawing 2500mA from batteries you can note down the time taken by battery to reach on 9.5volts and that is the limit of your batteries. This means you should always leave the amount of charge inside battery that can keep its terminal potential at 9.5Volts under loaded conditions.

You are partly right. Depending on type of battery, the charging time varies from 5 hours to 10 hours. Some sealed type batteries even recommended to be charged in 14hours. Lower the charging rate better will be the life of the battery. Overcharging is done either for revival after deep discharge or when one requires it to be quick charged. But for 1 hour discharge duty, it can not be charged in one hour for sure.

Something is wrong here!

My laptop battery is a good one, and it only has 5600mAh capacity. You have a battery just under half that capacity, and it is a cellphone battery? I don't think so!

I suspect you are trying to connect a larger battery to your cellphone to give it longer battery life. Unless the battery is correctly rated for the cellphone, you are in danger of destroying the phone. There are batteries available that are designed to be used as cellphone chargers. They are NOT cellphone batteries!

In any case, the wise thing is to use a charger that was specifically designed for that particular battery. Good chargers are not that expensive; get the right one and you'll save money in the long run.

Your laptop battery has 6 lithium cells in series, and is capable of delivering that 5600 mAh at around 18 V, a lot more energy than a cellphone battery, which is a single Li ion cell of just over 3 V. You are, however, correct in noting that 2500 mAh is a lot for a cellphone battery. the figure is more likely to be 700 mAh.

I quite agree this word" good charger are not that expensive;get the right one and you'll save money in the long run"

As far as i know if a Lead-Acid Battery is left uncharged for long time it damages, is the same thing happens for lithium-ion, Nickle-cadmium, Nickle-metal hydride batteries?

No body answered my question so far ?

You could answer your own questions by browsing at http://www.batteryuniversity.com/

With lithium-ion from what I've read there is less of a problem with leaving them in a discharged state then other types. Lead-acid will sulfate and the plates can swell to the point of cracking the case. Nickle-cadmium, Nickle-metal hydride I think will go through a chemical change that will reduce charge capacity that is not reversible.

I another word if several batteries in series and one discharges completely the other batteries will drive the battery in reverse and damage it. It is also possible to damage the equipment it's in.

A single cell will not do this because no other cells there to drive it in reverse.

This is true only for lead acid, NiCd and NiMH cells. It is dangerous to follow this advice with Li cells. If you want to use Li cells you must use the appropriate charger, which offers both current and voltage limiting.

Is that mean the Lithium-Iron battery the only battery which can be left on the shelf for infinite time with no damage ?

If you are talking about rechargeables, then long time, yes; infinite time, no. It is actually lithium-ion, not lithium-iron. There are, of course, also non-rechargeables with a long shelf life, such as zinc-silver oxide (button or coin cells).

can i use lithium ion battery to my ups?

is there any risk in that,if yes plz justify.

wat about the cost of lithium ion battery,is it costly than others?

The charging circuitry in any UPS is designed for a specific kind of battery. It will NOT correctly charge a battery of different chemistry. Yes - there ARE risks: to the UPS, to the battery, and to you! Overcharging, undercharging, explosion, and fire are some of the risks.

Fortunately, the costs of UPS units has dropped significantly in recent years. I hate to throw stuff out, but that is the wise thing to do! Throw the old one out and get a new one that is designed to use Li-ion batteries.

In my ups ,they provide lead acid battery.Now the battery died,i want to replace that battery with Nicad battery(cause its in my hand,no need to buy new one).hopefully therewont be any risk,

wat is ur opinion?

and tanx for tat nice explanation.

Then that UPS is designed for Lead Acid. Get a car battery (already nearly or fully charged before you initially connect it to the UPS) and a plastic tray for the battery, then connect with a couple of heavy wires, of course paying attention to polarity. Now you have a UPS with a longer running time.

Lead acid is nominal 2V/cell; NiCd is ≈1.25V/c

Could you please inform me :

What is the AH capacity of normal car battery ?

They vary from under 40Ah to over 100AH.

http://en.wikipedia.org/wiki/Car_battery, among others

Well, but if i only know the maximum starting current of my battery, how i can determine the AH capacity of that battery ?

Car battery is not rated by its AH but by the maximum current it can supply at start up.

If a car battery is rated at 100 Ah, that is what it can be expected to deliver without coming to harm. Because most interested mechanics can lay their hands on a voltmeter but few possess a suitable Ah meter, the alternative is to ensure that the voltage does not drop below 10.5V. There are other lead-acid batteries, so called deep-cycle batteries, which tolerate a deeper discharge, but they are not capable of delivering the high currents which a starter motor requires. The important thing is not to confuse the 10% permissible voltage drop with the 100% permissible Ah usage.

wat do u mean by 2V/cell?

Hi boss

Could you please answer this question:

Two Lead-Acid batteries, one is classified as deep discharge battery but the other is not- why that difference though both have the same chemist(Lead-Acid) ?

Thanks for your help

http://auto.howstuffworks.com/question219.htm

Dick

Car battery is a special type of Lead-Acid batteries which should never discharged below 90% of its full charge capacity.

So, you are allowed to get only 10% of its AH capacity into your load.

if Nicad battery is overcharged or undercharged by charger made for Pb battery,will it hv sme effect on battery life,or sme serious chemical explosion,damaging ups ckts ?

YES!

Some excellent information has been given on this thread. It is surprising to see how stubborn some readers are in not absorbing it.

all credit goes to dkwarner

will be thankful to him.