Lithium-Ion - or Li-Ion - batteries are in everything

Device manufacturers categorize batteries as 'consumables.' They're expected to wear out; it's how they do what they do. The warranties provided by computer companies usually have different coverage terms for a laptop's battery than for the computer's other components. Even if you take the best possible care of your battery, its performance will degrade over time, and I've found that batteries older than two or three years aren't good for much runtime at all. Accept the fact that yourApple laptop battery won't last forever, no matter what. Oxidation in the cells can prevent an old battery from discharging properly, so even when left on a shelf, a battery's lifespan shortens with time. That doesn't mean that there aren't some steps that you can take to ensure the Li-Ion batteries in your laptop or cell phone last as long as possible. Batteries are made to be used, so use them. Just like couch potatoes, batteries need exercise. The chemicals in Lithium-Ion batteries respond best to regular recharging. So if you have a laptop, don't keep it plugged in all the time; go ahead and let it drain to about 40 or 50 percent of capacity, and then recharge your computer. The life of a Lithium-Ion battery can be measured in charge cycles. A charge cycle occurs when 100% of a battery's capacity is used. Let's say you use 50% of your laptop's battery one day, charge it overnight, and then you use 50% of the IBM laptop battery again the next day. Even after charging it back up again, you'll have only had one charge cycle occur. Most laptop batteries are rated for a useful life of at least 300-500 charge cycles, but high-quality, properly maintained batteries can retain up to 80% of their original life, even after 300 cycles. Periodically calibrate your battery. Most batteries that have a 'fuel gauge', like those in laptops, should be periodically discharged to zero. This can be accomplished simply by letting your computer run until it reports a low-battery state and suspends itself. (Do not let your computer deep discharge, as I'll explain in the next item.) The gauge that measures the remaining power in your laptop is based on circuitry integrated into the battery that approximates the effectiveness of the battery's chemical compounds. Over time, a discrepancy can develop between the capacity that the internal circuitry expects the battery to have and what the battery can actually provide. Letting your computer run down to zero every month or so can recalibrate the battery's circuitry, and keep your computer's estimates of its remaining life accurate. Don't practice so-called deep discharges. Most laptops will suspend operation if the battery drains too low. Even if your computer goes to sleep, though, most batteries that are in good working order will still have a reserve charge available. This reserve will hold the computer's working memory in state for a little while. A deep discharge has occurred when even that percentage of reserve power is used up. The computer will have turned off completely, and sometimes you'll notice that it will have lost track of the correct date and time. Deep discharges will strain your batteries, so try to charge them frequently. Avoid exposing your battery to heat (when possible). Heat can overexcite the chemicals in your Sony laptop battery, shortening its overall lifespan. In fact, it's been speculated that the biggest cause of early battery expiration is the heat that batteries can be exposed to when they're stored in computers that are running off AC power. Laptops - especially modern multi-core machines - can get very hot when they're plugged in, easily over 100 degrees Fahrenheit. That's hot enough that extended exposure will negatively affect your battery. If you want to be really protective, there's nothing saying that you can't pop the battery out of your laptop if you're going to be within reach of a power outlet for a while. There may be times that you can't help but expose your laptop battery to heat; you may live in a warm climate, for instance. You can, however, try and avoid exacerbating the issue. Make sure your laptop is well ventilated and that you're not operating it on a surface that retains heat, even when you're not plugged into mains power. Store your batteries properly. If your laptop or portable device isn't going to be used for a while, you should remove its Lithium-Ion battery, if possible. Even if the battery can't be separated from the device, it should be stored in a cool environment at about one-half charge. Cool temperature is recommended by experts because that can slow the natural discharge that batteries will undergo even when they're disconnected from their device. I've seen some people go even further and recommend that spare batteries be stored in the refrigerator. I don't think this is a very good idea; I'm concerned about condensation that might build up. Don't put your batteries on ice, but keep them out of the sun. Ultimately, I believe that buying spare Li-Ion Lenovo laptop batteries is a losing game, because the batteries start degrading as soon as they're manufactured. Usually those spare batteries spend most of their time sitting in a charger, losing useful life. If you need to be really mobile, you're better off purchasing an adapter cable you can use with the power sources available in planes, trains, or autos. And, of course, by taking good care of the battery you already have.