Getting the Most From Your Laptop Battery

Some tips for extending the life of your laptop battery.

Sep. 24, 2008 — by .(JavaScript must be enabled to view this email address)

The battery plays a crucial role in a consumer’s overall laptop experience. Unfortunately, we usually don’t notice them until they start to fail on us. Understanding your laptop battery, knowing the different options available, and learning how to get the most out of yours can greatly improve user satisfaction. 

What’s Out There
Although lithium ion (LiON) rechargeable batteries are most common in today’s laptops, it wasn’t always the case. The first widely-used rechargeable was the nickel cadmium (NiCd). Useful in its day, inexpensive, and effective in a wide range of applications, the NiCd battery had a couple of drawbacks that needed improvement. One was the “memory effect,” (also known as “lazy battery”) where a battery that was recharged before being fully discharged would lose its full capacity, and instead “remember” the smaller capacity. The other drawback was the toxicity of nickel-cadmium (cadmium is a heavy metal). The next generation of laptop rechargeable batteries was the nickel metal hydride (NiMH), deemed a significant improvement over NiCd. For starters, NiMH batteries were non-toxic. They are considered more reliable, less expensive, and of higher capacity and output than NiCd batteries, and although they still suffer from the “memory effect,” it was less pronounced than their predecessor. 

The reigning king of the laptop battery is the lithium ion (also LiON or Li-Ion) battery. While more expensive than the previous two, LiON batteries do not suffer from any “memory effect,” are lighter than NiCd or NiMH batteries, and have a higher power density. The most current version of the LiON laptop battery contains a microprocessor that controls and monitors the charge and discharge rate, and feeds information to the laptop/user concerning remaining charge and estimated usage time. These advanced LiON batteries are commonly referred to as “Smart” batteries. 

If all laptop manufacturers are using lithium ion, why do battery capacities vary? To start, LiON batteries will differ in the number of cells included; the more cells, the greater the capacity. When purchasing a laptop from one of the bigger manufacturers (Dell, HP, IBM, etc.) the 6 cell LiON battery is most common. 8 or 9-cell varieties are often found as upgrades or purchasable as accessories, and will boast 20-30% capacity increase. Remember that each laptop differs, as well. Two different laptops using identical batteries may have very different runtimes. Usage time is subject to a great many variables, including processors, displays, and internal devices, to name just a few. Even if a manufacturer claims an 8-hour battery life (or 24-hours like HP), this will only be so under certain conditions. Think of it like the car industry’s Fuel Economy rating: the MPG figures are attained by running the car under ideal conditions, at a steady speed, on an inside treadmill. An actual driver uses the car much differently. Same deal with the laptop. 

When buying a replacement battery, be sure to match the voltage rating to the old battery. Batteries have three commonly advertised specs: voltage, amperes, and watt-hours. Watt-Hours (Wh) are found by multiplying the battery’s voltage and amp rating. Instead of amperes, manufacturers will often list milliamperes, and list the Milliamp-Hour (mAh) rating for the battery. For both Wh and mAh, a higher number means greater capacity. Keep in mind that batteries aren’t cheap. “My average cost for a decent 6-8 cell lithium ion battery is around $150,” says Anthony Cresegiona of BatteryMart, who also acknowledged that this was about one-third the price of a basic, stripped-down laptop. “Lithium isn’t cheap,” he continues, “but it’s a big improvement over NiCd and NiMH.”

Extending Battery Life
Lithium ion batteries do not require the same regular maintenance steps as the NiMH (e.g. routine full discharge/recharge to extend battery life), but there are a few commonly-accepted steps a user can take to get the most out of it. Before addressing those life-extending tips, consumers must first understand that a LiON battery loses capacity over time, and no amount of “cycling” (the process used with nickel-based batteries to restore full capacity) will return a LiON battery to its original state. Cell oxidation in a lithium ion battery is permanent, leads to charge loss, and cannot be halted. That said, getting the most out of each “cycle” or fully-charged battery can be done with the following steps:

Adjust Your Screen – If your computer’s power management options allow it, dim your screen to the lowest possible level. Set the screen for the lowest color setting (like 16-bit), as well. These two steps alone will do wonders. 

Close Applications – The more applications you have running, the more power you are using. Close down unused applications, particularly Adobe programs and Office programs. Do one task at a time, with the fewest necessary applications. 

Remove External Devices – Anything that plugs into your computer will consume power. This goes for USB devices (external hard drives, iPods, etc), memory cards, wireless EVDO cards – you name it. 

Plan Ahead – Let’s face it: we’ve all been on that long flight pleading with our laptop battery for just another half hour of life. Maybe we’ve realized our over-consuming mistakes too late, and with time running out we scroll and click frantically like Jack Bauer racing the clock, closing applications, dimming the screen, yanking memory cards out…if only we had done this before take-off! And that’s just what needs to happen. Prior to boarding, while plugged into the outlet at the gate workstation, take the necessary steps to prepare your laptop and your battery for the long flight ahead. If you have files to access on an external, transfer them to your laptop so you won’t have to plug in on board. Access your Power Management options and, if the feature is there, set the laptop for “Max Battery.” Take a few minutes to follow the above steps before you go to battery power, and you won’t be the questionable individual slamming your notebook on the tray table. 

As for lengthening the overall lifespan of a lithium ion battery, you can try storing it in a cool, dry place when not in use, and keeping it from extreme heat or prolonged exposure to sun. Anything over 95-degrees can reduce performance quicker. If you are going to be running on fixed power for some time, it is wise to consider removing the battery to keep it cool. When storing a lithium ion battery, do so with a 40-percent charge, and never stick it in the freezer. The refrigerator will do. 

The Future of the Notebook Battery
Intel co-founder Gordon E. Moore sagely predicted over 50 years ago that the number of transistors placed on the integrated circuit would double every two years. “Moore’s Law,” as it is now known, has held true, and been accurately applicable for many electronic devices such as computer processing speed, memory, and even digital camera resolution. Sadly, this exponential increase does not hold true for the laptop battery capacity. “There’s no question that battery technology does not keep up the pace with the rest of computer technology,” states Cresegiona, “and we won’t see a change from Lithium anytime soon.”

The Lithium-polymer battery – a lightweight, shapeable form of lithium-ion – has seen much usage in cell phone and PDA application, but the expense and lack of increased capacity over LiON has kept it from surging into the laptop market. LiON laptop battery capacity increases have been previously measured at around 6-to-8-percent per year, a far cry from the rate of advancement in other areas of computer technology. “Greater capacity in lithium ion is achieved a couple of ways,” says Isidor Buchmann, founder and CEO of Cadex Electronics, and author of Batteries in a Portable World. “Reducing the thickness and increasing the density of the separating plates is one way,” he continues, “but it can also lead to complications and recalls.” Lithium may be making headway into other areas of application – most notably cars and solar-power storage – but it might be some time before we see it replaced in our laptops by the next new power source.

The fuel cell is one possible source. This past July PolyFuel, a company engineering membranes for fuel cells, announced a prototype power supply for laptops that consists of small cartridges of methanol fuel. Each cartridge is about the size of a deck of cards, and can be swapped out while the computer is still running. According to the company’s info, a single cartridge could potentially power a converted laptop for up to 10 hours. Refillable, the methanol cartridges would be lighter than the LiON batteries they promise to replace, and some suggest that 10-hour runtimes aren’t even close to the technology’s full potential.

Some, like Buchmann, are skeptical about fuel cells powering our laptops. “There is no replacement for the lithium-ion battery,” Buchmann insists, adding that the current fuel cells being tested are not powerful enough to run a laptop. Whether your fuel cell glass is half-full or half-empty, fuel-cell-powered laptops won’t be hitting shelves for a while, and until then consumers best get the most out of their lithium ion.

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