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
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