How to buy a laptop battery?

As of the date of this writing there were 19,300,000 results in a Google search for the keyword laptop battery. On the one hand that is great if you are in need of one but at the same time overwhelming. How do you know what to buy, from who to buy, and what you even should be looking for when buying a laptop battery? I have identified seven categories a person needs to be informed about when going out to make a purchase for a new battery and they include: Part number, Make, and Model; and Chemistry; and Capacity; and Voltage; and Watt Hours; and Number of Cells; and finally the Retailer, Price and Warranty.

Part Number, Make, and Model

Essential to the purchase of your new laptop battery is the part number.  A part number is a unique identifier that is assigned to a part to simplify referencing and to unambiguously define a part within a single manufacturer. The part number above all is what needs to be known before going to buy your battery. Secondly the make and model are next most important part identifiers you must know.  The make is the manufacturer (e.g. Sony, HP, Dell). The model is a multi-component word that includes the line and actually model number. For example the Sony VAIO VGN-FZ90S is an example of a sony made laptop that is part of the VAIO series and which has model number VGN-FZ90S.

Most laptop’s hold this information within your computer’s system info. To access this info go into the properties of your computer and view the model information. The battery’s part number can be found on the battery itself.


Most laptops now require a lithium based battery chemistry. You cannot choose your chemistry type for most batteries.  It is still good however to know which chemistry type yur battery requires.


Capacity also known as runtime Battery capacity quantifies the total amount of energy stored within a battery. More capacity equals a longer runtime between battery charges. Battery capacity is measured in amperes, which is the volume of electrons passing through the batteries electrolyte per second. A milliAmp hour (mAh) is the most commonly used notation system for consumer electronic batteries. Note that 1000 mAh is the same as 1 Ah.

When buying a battery knowing how much capacity you may need depends on: how much you want to spend, how often and how long you use your laptop on battery power, and what applications you my be running off the battery’s power. The higher the capacity the more money you will spend, so if you need the longer runtime’s or you use applications that require more battery juice then buy the higher capacity.


Volts – or V – is an electrical measurement of energy potential. Mathematically voltage is commonly measured by V= I x R; where V=Voltage, I=Current, R=Resistance.  Voltage can also be defined as Electrical Potential difference – a quantity in physics related to the amount of energy that would be required to move an object from one place to another against various types of force. In the fields of electronics the electrical potential difference is the amount of work per charge needed to move electric charge from the second point to the first, or equivalently, the amount of work that unit charge flowing from the first point to the second can perform. A battery contains four unique types of voltage measurements. Each voltage measurement type residing in a battery effects battery life.

  • Float Voltage – is battery voltage at zero current (with battery disconnected).
  • Nominal Voltage – is battery voltage range 3.7V, 5.2V, 10.2V, 12V etc that says that a voltage range exists depending on the number of cells in the battery. For example a 12 Volt battery is made of 6 cells and has a Float voltage of about 12V.
  • Charge Voltage – The voltage of a battery while charging.
  • Discharge Voltage – The voltage of a battery while discharging. Again, this voltage is determined by the charge state and the current flowing in the battery.

For laptop batteries the most common voltage measurements are: 7.2V, 9.6V, 10.8V, 11.1V, and 14.4V. Since you cannot choose the voltage measurement for your laptop go with whatever measurement is closest to your original battery. Remember nominal voltage allows for slight deviation from the original but you cannot use a 7.2V battery if it requires 14.4V. The best example would be a 10.8V battery could be used with an 11.1V battery.

Watt Hours

Whr, Watts, Volts and Amperes are basic units of measure for a DC (Direct current) power supply. A battery, for example, is a direct current power supply and the combined measure Volts x Amps = Watts.  Watts are important because watts represent the electrical energy spent by a battery (power generator) and used by an electrical device. Watts in effect is the measure of the amount of work done by a certain amperage (amount) of electric current at a certain pressure or voltage.  Watt hours are measured by multiplying volts and capacity together (and commonly rounding up).

Number of Cells

The number of cells is important since the more cells contained in the battery the higher the capacity will be. To determine the number of cells in your laptop battery you need to have some general idea of what cells are being used in your battery. The most common battery cell is the 18650 and is manufactured by LG, Sony, Sanyo, Samsung, Panasonic and many others.  The 18650 is a 3.6V cylindrical Li-Ion cell. 18650 has no memory effect (distinguish between digital memory effect) and longer storage life than NiMH battery cells. 18650 is light weight and has a high energy density. It is in effect perfect for building batteries for laptop and other portable power devices.

Specifically the 18650 battery cell has a nominal voltage average of 3.7 V. It has a nominal capacity of 2200 mAh. It has a maximum charge current of 2.4 Ah and a max discharging current of 4.6 Ah. Its dimensions (DxH) are 18.3 mm (Max 18.4) x 64.9 mm (Max 65.1). It weighs   46.5 g (1.64 oz) .  It has cell cycle performance of 80% of initial capacity at 300 cycles. All in all the 18650 is a very good battery cell.

Using this common laptop battery cell as our base you can determine the number of cells in your laptop battery by doing the following. Divide the battery’s stated voltage by the 18650’s nominal voltage to get the number of cells in series and divide the battery’s stated capacity by the 18650’s nominal capacity to get the number of cells in parallel. Then multiply the results of the series and the parallel to get the total number of cells in the battery.

Retailer, Price and Warranty

Once you have all the above information now it is time to pick and choose a retailer to buy from. When choosing a retailer to buy a laptop battery from take into consideration the retailer’s reputation, the price, the warranty, and the return policy. Be sure to chat or speak with one of their representatives if you have questions. Be smart about where you buy from and only buy from a reputable retailer. With batteries you never want used and you always want to be sure that is a problem arises the retailer will be there to make it right.

Until next time, Dan Hagopian –
Copyright © All rights reserved.

Buying Batteries: How To Buy A Battery?

We buy batteries first because we need them and then secondly we buy them at the cheapest possible price. Considering that 75% of the world’s batteries are made by Chinese manufacturers, regardless of brand then it makes sense to buy the cheapest battery available knowing full well that I will have to buy another replacement battery sooner rather than later. But who cares as long as it is cheap (buy cheap – buy often)! However if I wanted to make a better battery purchase what considerations would I have to factor? In other words how do I buy a battery that gives me the best value for my dollar?

Swap-meet shopping (that brings back childhood memories) is the ultimate in buying cheap gems. But can I buy a battery at swap-meet prices and be satisfied because I bought the best battery, the longest lasting battery, the best price battery? Buying a battery is not as easy as it first may seem. Most people believe that if you bought an iPod Nano, for example, you would need to buy your battery replacement directly from Apple. Savvy battery shoppers know there is a cheaper and better way of getting their battery replacement. Incidentally Apple does not manufacturer batteries directly – they outsource them to Chinese manufacturers and then affix their own private label to the batteries. Take the private label off and their just like the ones sold by other retailers.

Now before you go out and by your next battery replacement you do need to know a few things including:

  • My Device’s Battery
  • Battery Chemistry, Battery Voltage, and Battery Capacity
  • Battery Price

My Device’s Battery

Your device, be it a PDA, Laptop, iPod, MP3, Camera, Barcode Scanner, Twoway Radio (or any other device) will have a battery that was manufactured  specifically for it. Typically the battery part number will be listed directly on the battery label. The battery part number is often times different from the device’s model number. For example a 167648 battery part number fits the iPAQ 3600 PDA. Interestingly enough the 167648 also fits the IPAQ H3600, IPAQ H3135, IPAQ H3150, IPAQ H3630, H3635, IPAQ H3650, IPAQ H3660, IPAQ H3670, IPAQ H3760, and the IPAQ H3765. In addition to this the 167648 also has alternative or compatible part numbers that is associated with including: COMPAQ DLP 305590, COMPAQ 305590, COMPAQ 3S619-001. This type of numbering sequences within the realm of electronics is quite common as each number though relating to the same device is different due to batch manufacturing, marketing procedures and business management processes. But the same battery, in this case, the 167648 fits with all the numbers above.

In order to buy the right type of battery for your device you must first and foremost know your deice model number. That is actually the best. So if you know you have an iPAQ 3600 then the best way to locate the iPAQ H3630 battery is to search with that model number. If you know your device’s battery part number then that is even better, but at the bare minimum you need to know that you need a battery for an IPAQ H3630. Once you have that information then you can consider the battery’s chemistry, the battery’s voltage, and the battery’s capacity.

Battery Chemistry, Battery Voltage, and Battery Capacity

Next when buying your replacement battery you need to know the battery’s technical ratings. The technical ratings include the battery’s chemistry, the battery’s voltage, and the battery’s capacity. This will get slightly technical but we will go slow and keep the tech lingo at a surface level only.

To begin with a battery is a device that converts chemical energy into electrical energy. The basic design of a battery includes two electrodes, an anode and a cathode. Batteries have two electrodes, an anode (the negative end) and a cathode (the positive end). Collectively the anode and the cathode are called the electrodes. What is positve and what is the negative terminal? It would be great to simply say that the anode is negative and the cathode is positive, however, that is not always the case. Somtimes the opposite is true depending on battery technology. 

In between the battery’s two electrodes runs an electrical current caused primarily from a voltage differential between the anode and cathode. The voltage runs through a chemical called an electrolyte (which can be either liquid or solid). This battery consisting of two electrodes is called a voltaic cell. To convert chemical energy into electrical energy the battery must contain the chemical base. Common battery chemicals in use today are: Nickel-cadmium batteries, Nickel-metal-hydride batteries, Lead-acid batteries, Lithium-ion batteries, Lithium-ion-polymer batteries, Reusable Alkaline batteries. Choosing your battery’s chemistry is typically not an option since your device’s design was specific to one chemical or another. But it is still good to know what type of chemical is used in your battery.

The other feature that is also not optional to change is your battery’s voltage. Battery voltage is an electrical measure of energy potential. Voltage can be thought of as the amount of "pressure" of electrons that pass from a negative connector to a positive connector. Voltage can also be defined as the Electrical Potential difference – a quantity in physics related to the amount of energy that would be required to move an object from one place to another against various types of force. In the fields of electronics the electrical potential difference is the amount of work per charge needed to move electric charge from the second point to the first, or equivalently, the amount of work that unit charge flowing from the first point to the second can perform. Actually voltage is strictly a mathematical product of V= I x R; where V=Voltage, I=Current, R=Resistance. Another words a measurement.

Voltage depending on the type of battery can be measured and is listed on the battery at 3.6V, 2.7V, 7.4V, 14.4V for example. What makes buying a battery difficult, especially when trying to match up the replacement battery’s voltage with your current battery’s voltage is the measurement of nominal voltage. FYI there are a number of different types of voltage including: Float Voltage, Nominal Voltage, Charge Voltage, and Discharge Voltage.

In the case of nominal voltage a device that requires a 3.7V battery will work with a 3.6V battery. But a 12V battery would not do the trick. Another words small voltage deviations are ok – just not big ones.

The final technical rating requirement you will need to know is the battery’s capacity. Battery capacity is a reference to the total amount of energy stored within a battery. Battery capacity is rated in Ampere-hours (AH), which is the product of: AH= Current X Hours to Total Discharge Amperes (commonly "Amps"). Thinking about this another way battery capacity of AH is a measurement of the quantity of the number of electrons passing through a given wire per second. In a single Ampere there are 62,000,000,000,000,000,000 electrons per second! More Amps, More electrons, More current! More is better! So if your existing battery is say 1000 mAh (1 Ah) and your replacement battery 1800 mAh (1.8 Ah) then the 1800 mAh battery offers a higher battery capacity which means your device will run longer. The bigger the capacity the longer your device will run.

Battery Prices

When buying your battery replacement price is something to consider. When considering your price you need to match and compare the technical ratings, the retailers warranty, the retailer’s level of service, the overall value of the retailer. Reading retailers testimonials are good to do as well. Factor in shipping costs and the availability at the retailer for your battery replacement.

Until next time – Dan Hagopian
Copyright © All rights reserved.

Battery and Electricity Vocabulary

(Glossary of Terms)

Ampere – The unit used to measure the electric current or
flow of electrons through an electrical conductor or circuit.

Atom- The smallest particle of an element that can exist
either alone or in combination; it is also known as the
building block of matter. An atom can be electrically
neutral or have a positive or negative charge. If it has either
a positive or negative charge, it is called an ion. The charge
is determined by the number of electrons (which carry a
negative charge) compared to the number of protons (which
carry a positive charge). The negative charges (electrons) of
the atom can move from one object to another for certain
materials (see Conductor).

Battery- A source of electrical energy that is created by a
chemical reaction and pushes electric charges within a circuit.

Battery Terminal- The connecting points or locations on a
battery where the electrical charges leave or enter the battery.

Circuit- A path through which electricity flows.

Closed Circuit- A completes electrical circuit or path
through which electricity or current can pass or flow.

Conductor- Materials through which electrical current can
flow. Copper is a good conductor. Most electrical wires are

Electric Motor- A device that converts or changes electrical
energy into mechanical energy.

Electric Charge- An electrical property of an atom, described
as either positive or negative.

Electric Current- A flow of electrons; the quantity of
electrons that moves through the circuit. Electric current is
measured in amperes (amps).

Electric Discharge- The jumping of electric charges between
two objects.

Electrical Energy- Form of energy created by the flow of
electrons; this energy allows the completion of work.

Filament- A wire or similar part of a light bulb through
which electricity flows; it glows from the heat generated by
passage of the electrical current.

Power Generator- A device that changes or converts
mechanical energy into electrical energy.

Insulator- Materials that do not easily carry or allow the
passage or flow of an electric current. Examples of insulators
are glass, rubber, plastic, and air.

Ion –Any atom or molecule that carries an electrical charge,
either positive or negative.

Magnet- An object that pulls or attracts iron or steel and has
a force around it. The pull or attraction is strongest at its ends
or poles, and they are labeled North and South.

Magnetism- The force around a magnet.

Ohm- The unit used to measure the resistance to the flow of
electrons or electric current.

Open Circuit- A circuit or electrical path that is broken or
incomplete, and so electricity cannot flow through it.

Parallel Circuit- An electrical circuit in which the electricity
can follow more than one path. It is a circuit that connects
several objects or resistances in a way that allows each
resistance to have its own path. This is the way appliances and
lights are connected in homes, so they do not all have to be
on at once.

Resistance- A measure of how well electricity moves through
a material. Insulators have high resistance; conductors have
low resistance. Resistance of an object is measured in ohms.

Series Circuit- A circuit in which all the lights or resistors
are connected in sequence, or one after the other, forming a
single path through which the electricity can flow. Batteries
in a flashlight and in small, portable radios are frequently
connected in series.

Static Electricity- Electricity that is motionless or at rest; it is
produced by rubbing two objects together, such as a resin rod
and a piece of silk fabric, or a balloon against a piece of wool

Switch- A device that allows an electrical circuit to be opened
or closed.

Voltage – The force or push, given by a battery or generator
that moves electrons from one place to another in an electric
circuit or conductor.

Volts – The unit used to measure voltage.

Watts- A unit for measuring how quickly or how much an
appliance or other device uses electricity.

iPaq Battery – iPaq PDA History

iPaq batteries have been available since the first iPaq PDA was released in 2002. This iPaq by the way was the HP iPAQ h5450. The IPAQ H5450 Battery technology consists of: a Polymer Lithium battery cell and rated at 3.7 volts and a capacity of 1400 mAh. The IPAQ H5450 battery contains integrated power management circuits that protect against over-voltage and under-voltage conditions and maximizes battery life between charges, minimizes charging times, and also improves overall battery life.

Additional iPaqs and their release dates are:

HP ipaq rx5915 Travel Companion (released 2006)

HP ipaq hw6900 Mobile Messenger (released 2006)

HP ipaq hx2790 (released 2005)

HP ipaq hx2490 (released 2005)

HP ipaq hx2190 (released 2005)

HP ipaq rx1950 (released 2005)

HP ipaq hw6500 Mobile Messenger (released 2005)

HP ipaq hx2110 (released 2004)

HP ipaq hx2410 (released 2004)

HP ipaq hx2750 (released 2004)

HP ipaq rx3115 (released 2004)

HP ipaq hx4705 (released 2004)

HP ipaq rx3715 (released 2004)

HP ipaq rx3415 (released 2004)

HP ipaq rz1715 (released 2004)

HP ipaq h6315 / h6320 (released 2003)

HP ipaq h4350 h4355 (released 2003)

HP ipaq h5150 (released 2003)

HP ipaq h4150 h4155 (released 2003)

HP ipaq h1940 h1945 (released 2003)

HP ipaq h5550 h5555 (released 2003)

HP ipaq h2210 h2215 (released 2003)

To find an ipaq battery for any of the ipaq’s listed above then visit

Until next time – Dan Hagopian,

Buying Batteries – Brand New, Used or Refurbished?

When buying a battery for your mobile device (PDA, iPod, Digital Camera etc.) make certain you are only buying new batteries – never buy a used or refurbished batteries!

Why? The answer to that is analogous to the question ‘Would you Buy a Half Eaten Sandwich?’ The answer undoubtedly is no! Let me explain…

A battery is a device that stores chemical energy and through an electrochemical process (electromotive force) converts the stored chemical energy into electric energy via a direct current. The chemical conversion is a process of chemical change created by adding or losing chemical substances (electrons, oxygen, lithium etc.) inside the battery and used by a connecting device (i.e. PDA, iPod, Digital Camera).

Inside the battery as the chemical conversion begins a reaction produces an electron flow. If the electrons are not flowing between the anode, cathode, and electrolyte then the battery can sit on the shelf for a year or more. However, once the chemical is activated oxidation and reduction occurs and the flow of electrons takes place, thereby creating a direct electrical current. Considering that electrons flow a 62 quintillion per second (62,000,000,000,000,000,000 electrons per second) then it takes only a very small moment for power to be created and here is the kicker – the only way to stop is to let the chemical exhaust itself!

How is the chemical inside my battery activated? The technical answer is by placing a load on the battery (i.e. by connecting your battery to a device regardless if the device is turned on).  The basic operation is that electrons collect on the negative electrode, when a substance (i.e a wire, an electrolyte) is placed as a separator between the negative electrode and the positive electrode the electrons flow (are drawn) to the positive electrode. This flow creates a current. The electron current, or electricity, can then be directed to a device and used as a power stream.

Once electrical current is established then the only way to stop it is to let the chemical degrade to the point where the capacity is almost non-existent. This is called battery degradation and begins once the chemistry has been activated. Battery degradation is the normal wear and tear effect of battery usage and its inevitable effects are declining capacity, increasing internal resistance, elevated self-discharge, and premature voltage cut-off on discharge.

Because of these things you do not want to buy a used battery or a refurbished battery.

Until next time, Dan Hagopian
Copyright © All rights reserved.

How Long Will My Battery Last?

Battery life depends on many factors:

  • the battery chemistry
  • the quantity and quality of the load on the battery
  • the number of recharge cycles
  • the length of non-use
  • the age of the battery
  • the internal design of the battery
  • the usage

These are some of the basic factors that will dictate how long your battery will last. Personally I have seen some battery's capacity (ability to power a device) last for 36 months whereas other battery's last only 8 months. Road warriors (people who use their battery power 3-4 hours per day – or more – will generally use the useful life of their battery a lot quicker than those people who use their battery power about 10-15 minutes per day.

One thing for sure every battery will die. Battery Replacements however are easy to find however.

Until next time – Dan Hagopian,
Copyright © All rights reserved.

Hard Reset or Soft Reset On Your iPAQ

There are two types of iPAQ Resets you can do: a soft reset and a hard reset. Many times a either a soft or hard reset is necessary after installing new hardware like a battery.

A soft reset stops all open programs and "reboots" your iPAQ. When the iPAQ powers back up, you'll start with all programs closed and the unit will be ready to use. The soft reset is intended to reset the iPAQ if it is malfunctioning or has become bogged down. A reset could also be necessary after some software is installed.

A soft reset are similar on all iPAQ models but there are definite differences from model to model. For example on the iPAQ 1900 Series Pocket PCs you can perfom a soft reset by pressing the tiny recessed button on the left-hand side of the unit. There is a reset nib in the stylus that can be found by unscrewing its top.

A hard reset on the other hand wipes the RAM and returns the iPAQ to its factory specs. In effect, after the hard reset, the Pocket PC will be just as it was when you purchased it. All data entered, preferences set or software installed on the Pocket PC after purchase will be lost after a hard reset and will have to transferred or reinstalled via ActiveSync.

Hard resets are similar on all iPAQ models but there are definite differences from model to model. For example on the iPAQ 1900 Series Pocket PCs a hard reset can be performed by pressing and holding the power button at the top of the unit while simultaneously pressing and holding tiny recessed reset button on the left-hand side of the unit. Make sure that you press and hold the power button before pressing and holding the reset button. Keep both buttons pressed for several seconds until the screen fades. Turn the unit back on. The iPAQ will now be as it was when it left the factory and you can start fresh.

Until next time – Dan Hagopian,
Copyright © All rights reserved.