Research has brought about a variety of battery chemistries, each offering distinct advantages but none providing a fully satisfactory solution. With today’s variety of battery types, better choices can be made to suit specific user applications. This paper talks about the recommended battery chemistry for cell phones and two-way radios in terms of energy density, durability and price.

What’s the best battery for cell phones?

Early cell phones were powered with nickel-based batteries but most newer phones are now equipped with lithium-ion. This chemistry is lightweight, offers high energy density and lasts long enough to span the typical life of the product. Lithium-ion contains no toxic metals.
To obtain thin geometry, some cell phone manufacturers switched to lithium-ion-polymer.

This satisfied consumer requests for slim designs. In the meantime, technological advancements also made low profile lithium-ion possible. lithium-ion packs are now available in 3 mm, a profile that suits most designs. lithium-ion has the advantage of lower manufacturing cost, better performance and longer cycle life than the polymer version.

Lithium-ion is a low maintenance battery(dell inspiron 1520 battery apple a1185). No periodic discharge is needed and charging can be done at random. A random charge means that the battery does not need to be fully depleted before recharge. In fact, it is better to recharge before the battery gets too low. Full discharges put an unnecessary strain on the battery. A recharge on a partially charged battery does not cause memory because there is none.

Charging lithium-ion is simpler and cleaner than nickel-based batteries but the chargers require tighter tolerances. lithium-ion cannot absorb overcharge and no trickle charge is applied on full charge. This allows lithium-ion to be kept in the chargers until used. Some chargers apply a topping charge every week or so to replenish the capacity lost through self-discharge while the battery(sony vgp-bpl8 battery) sits idle in the charger. Repeated insertion into the charger or cradle does not damage the battery though overcharge. If the battery is full, no charge is applied. The battery voltage determines the need to charge.

On the negative side, lithium?ion gradually loses charge acceptance as part of aging, even if not used. lithium?ion batteries should not be stored for long periods but be rotated like perishable food. The buyer should be aware of the manufacturing date when purchasing a replacement battery. Aging affects battery chemistries at different degrees.

Counterfeit cell phone batteries (clone batteries)

In the search for low-cost battery replacements, consumers may inadvertently purchase clone cell phone batteries that do not include an approved protection circuit. Lithium-ion packs require a protection circuit to shut off the power source if the charger malfunctions and keep on charging, or if the pack is put under undue stress (electrical short). Overheating and ‘venting with flame’ can be the result of such strain. (See photos of an exploded cell phone with clone battery on charge.)

Cell phone manufacturers strongly advise customers to replace the battery(sony vgp-bpl5a  dell inspiron 6400 battery) with an approved brand. Failing to do so may void the warranty. Counterfeit cell phone batteries have become visible since the beginning of 2003 when the world was being flooded with cheap replacement batteries from Asia.

Cell phone manufacturers act out of genuine concern for safety rather than using scare tactics to persuade customers to buy their own accessories. They do not object to third party suppliers in offering batteries and chargers as long as the products are well built, safe and functioning. The buyer can often not distinguish between an original and a counterfeit battery(vgp-bps9 sony vgp-bps9 battery) because the label may appear bona fide.

Caution should also be exercised in purchasing counterfeit chargers. Some units do not terminate the battery correctly and rely on the battery’s internal protection circuit to cut off the power when fully charged. Precise full-charge termination and a working protection circuit are needed for the safe use of the lithium-ion battery.

What’s the best battery for two-way radios?

Most two-way radios use nickel-cadmium. These batteries are durable and forgiving if abused. But nickel-cadmium batteries have only moderate energy density and are environmentally unfriendly. Environmental agencies have been discouraging its use, especially in Europe. The recommended alternative is nickel-metal-hydride, a battery(HP Pavilion DM3 battery) that has higher energy density and contains no toxic metals. nickel-metal-hydride has been tested in two-way radios for a number of years but the results are mixed. Shorter than expected service life is the major drawback.

For two-way radios, nickel-metal-hydride has a cycle life, which is half that of standard nickel-cadmium. nickel-metal-hydride prefers a moderate discharge current of 0.5C or less. A two-way radio, on the other hand, draws a discharge current of about 1.5A when transmitting at 4W of power. High discharge loads and sharp pulse currents shorten battery life.

To compare the longevity of nickel-metal-hydride under different load condition, a test was carried out in which batteries of the same type were discharged with a DC and digital load. In both tests, the batteries were discharged to 1.04 volts per cell. The DC load was a steady 500mA; the digital load simulated the Global System for Mobile Communications (GSM) at 1.65 ampere peak for 12 ms every 100 ms with 270 mA standby. (Note that the GSM pulse for voice is about 550 ms every 4.5 ms).

With the DC discharge, nickel-metal-hydride wore out gradually, providing an above average service life. At 700 cycles, the battery(hp elitebook 2530p battery) still provided 80% capacity. By contrast, the same battery type faded more rapidly with a digital discharge and the 80% capacity threshold was reached after only 300 cycles. This phenomenon indicates that the kinetic characteristics for nickel-metal-hydride deteriorate more rapidly with a digital than analog load. Although the test was simulating a GSM cell phone, Tetra and other digital two-way radios have similar loading.

Let’s briefly compare the characteristics of nickel-cadmium and nickel-metal-hydride. nickel-cadmium has the advantage of maintaining steady high capacity and low internal resistance through most of its service life. nickel-metal-hydride, on the other hand, starts with good capacity and low internal resistance but the resistance increases after a few hundred cycles, causing the voltage to drop on a load. Even though the energy may still be present, the battery(vgp-bps8) cannot deliver the high current during transmit and the message cuts off. The radio becomes unreliable.

Nickel-based batteries are high in maintenance. Periodic discharge cycles are needed to prevent crystalline formation on the cell plates, also known as memory. nickel-cadmium is more receptive to memory than nickel-metal-hydride because both nickel and cadmium plates are affected by memory.

Nickel-cadmium should be exercised once ever 1 to 2 months, whereas nickel-metal-hydride can get by with a deliberate full discharge once every 3 months. Without proper maintenance, the advantage of nickel-cadmium over nickel-metal-hydride in terms of cycle life cannot be realized.

Lithium-ion has been tested for two-way radios and the results are positive. Substituting lithium-ion with nickel-based will require chargers specifically suited for this chemistry. While nickel-cadmium and nickel-metal-hydride can often share the same charger, lithium-ion uses a different charge algorithm. There is also a cost premium for lithium-ion. Future two-way radios will undoubtedly be fitted with lithium-ion.

We’re not sure we’ve seen this much crapware installed on a PC before. Trend Micro is the trial antivirus of choice, while Asus(eee pc 1000he battery ) has shoehorned not one, but two toolbars into Internet Explorer in the form of the Google Toolbar and Windows Live toolbar. There’s an eBay icon on the desktop, another icon that’s an awful attempt to sell software, even more onsell, Asus’ trial web storage and a Wi-Fi app installer from Boingo. It also gives Minority Report’s advertising a good name.

By default it’s occupied by the wireless adapter, though, so there’s not much point in replacing it. As for the battery, the A1 model includes a large 6-cell apple a1185  battery; other models (likely not in North America) may go with a smaller 6-cell 63Wh battery.

The Gateway NV5933u  $649 price stands out in this laptop class, but this model is about much more than a low price. The internal components offer good everyday performance if you’re not a major gamer, and the standard Blu-ray disc drive is a sweet feature, even if most users will find it nonessential. If you can’t make do with this machine’s level of graphics performance, the Acer(dell xps m1530 battery) Aspire 5738PG Multi-Touch is not a bad bet for $150 more; plus, you’ll get a multi-touch display in the deal. But the size of that price difference underlines what a good deal the    laptop is for general use.

Once you’ve wiped the drool from your face (I’m not going to lie, I restarted it three times just to watch it boot that quickly), you’ll notice a lot of your settings are missing in your apps. This is because a lot of those preferences are stored in your home folder, which we didn’t copy over. To fix this, head into System preferences and open up the Accounts pane.

While the highly portable nature of notebooks exposes them to the knocks and bumps that are an inevitable feature of life on the move, this Sony (vgp-bpl8 vgp-bps8) model features a 3D-accelerometer monitoring system that detects freefalls, shocks and vibrations and protects the integrated HDD to secure against the loss of any personal data.

The Plantronics Backbeat 906 has a flexible headband design and the earphones are designed similar to those earlier Bose In-ear headphones. The headband is made of a flexible rubber band which can be folded and twisted. This flexible design makes wearing them comfortable even while lying on the bed. You could also just fold and tuck them away in your shirt’s pocket. This made the sony vgp-bps10 battery  Backbeat 906 easy to lug around. The earpiece supports three-way adjustment for better fit but fitting the earpiece tightly into the ear canal is tough. On the other hand, the headset looks good and has good build quality.

Many Australians enjoy reading outdoors and eInk is the best screen technology for this purpose because it’s easy to read even in bright sunlight. We confirmed this by reading a book with the $US489 Kindle DX in the middle of Sydney’s Hyde Park at noon on a bright sunny day.

Any hopes that the new processor might aid battery life were soon dashed, too. Just 3hrs 36mins of light usage is almost the same as before. Considering the Studio 1557 had a hotter quad-core Core i7 processor thrumming away under the hood, it  disappointing. If you need longer vgp-bps10 battery life, you抣l just have to consider the optional 9-cell battery which comes at a ?1 inc VAT premium.

How much better? Try >50x reduction in idle power, >20x reduction in audio power and 2-3x power reductions in browsing and video compared to the previous-generation Atom (a.k.a., “Menlow”) processor. These efficiencies translate into >10 days of standby, up to two days of audio playback and four to five hours of browsing and video life with common 1500mAh laptop batteries.

The Apple iPad is the device that single-handedly justified a tablet market for many manufacturers. It has a simple operating system based on the iPhone, a 10-inch touchscreen, fantastic hp elitebook 2530p battery life (10 hours) and access to hundreds of thousands of apps that can collectively do just about anything. It’s not perfect, but it set a high standard. Base models start at $500 for 16GB of storage and Wi-Fi; price goes up for 3G connections and more storage.