Software Development

The care and feeding of Li-Ion batteries

Lithium-Ion—or Li-Ion—batteries are in everything, and while they may not last forever, they'll benefit from a little tender loving care. This time, five strategies that will help your users get the most out of the rechargeable batteries in their laptops and portable devices.

Lithium-Ion -- or Li-Ion -- batteries are in everything, and while they may not last forever, they'll benefit from a little tender loving care. This time, five strategies that will help your users get the most out of the rechargeable batteries in their laptops and portable devices.

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 your 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 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 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 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.

12 comments
batterynotebookcomau
batterynotebookcomau

In science and technology, a battery is a device that stores energy and makes it available in an electrical form. It converts chemical energy into electrical energy, producing an electric current when connected in a circuit. The finished battery is an electrically connected group of cells (wired in series) that stores an electrical charge and supplies a direct current (DC). We usually call finished battery as battery pack and unfinished battery is called as cell. # What is a Battery? # How to classify the battery? # What are the differences between Primary Battery and rechargeable battery? more battery news at http://www.battery-notebook.com.au blogs

batterycompanycomau
batterycompanycomau

New batteries are shipped in a discharged condition and must be charged before use. We generally recommend an overnight charge (approximately twelve hours). Refer to the user's manual for charging instructions. Rechargeable batteries should be cycled - fully charged and then fully discharged - two to four times initially to allow them to reach their full capacity. (Note: it is normal for a battery to become warm to the touch during charging and discharging). New batteries are hard for the device to charge; they have never been fully charged and are therefore "unformed". Sometimes the device's charger will stop charging a new battery before it is fully charged. If this happens, remove the battery from the device and then reinsert it. The charge cycle should begin again. This may happen several times during the first battery charge. Don't worry; it's perfectly normal. More laptop battery care news at http://www.ebattery.com.au

batterycompanycomau
batterycompanycomau

Li-ion: Lithium Ion. This is one the newest battery types available. It can offer the same power as a Ni-MH battery in a smaller and lighter package. This type does not suffer from 'Memory Effect' but it is expensive to manufacture. more battery care at http://www.battery-company.com.au blogs

kenmo
kenmo

I disagree on the refrigerator storage issue. If the battery is placed in a plastic bag and sealed reasonably well, and allowed to warm up in the bag before opening it after storage, no condensation problem. And it really is better to store them like this. Also, for long term storage, discharge them to 40% or so before storage for best life. Otherwise, a great article with much needed info!

danarid
danarid

I have read that lithium batteries should never be completely discharged, that complete discharge will ruin them. This point should be checked out with Li-Ion manufacturers. On the other hand, batteries using zinc or cadmium (Ni-Cd) develop whiskers extending out from the zinc or cadmium surface on recharge and these whiskers grow with partial discharge and recharge. Full discharge then recharge destroys these whiskers and they never become a problem. This point needs rechecking also. DRidgley

Dr Dij
Dr Dij

as I call them. I mainly use prides of li-ions for photo shoots; have to charge 6 or so 3 hour batteries for 8 hour shoots (flash and the internal 3w video light reduce the actual from rated time). I've had weird things happen: batteries will suddenly die, more often the cheap brands. I have batteries that won't charge in the Sony charger but will charge in 3rd party brands. I have one battery that say 3 hours as you mentioned but give up after 1 hour. Have been trying to figure out how the logic inside them works. I end up numbering them so I can tell which are going bad. Also have humongo lions for video light. The 15 hour camcorder batteries last 2.5 hours in a 10w video light or less with it on 20w. but they sure help bring out the colors in your shots. I always 'top them off' before shoots because they lose a little just sitting, which you couldn't do with ni-cads due to memory effects. I guess we'll eventually switch to micro-fuel cells, with twice the energy density of lions.

williamjones
williamjones

There were several resources that I found useful when putting this together. Apple Computer's Battery information pages http://www.apple.com/batteries/ Cadex Electronics' Battery University http://www.batteryuniversity.com/index.htm If you need to replace your battery, you should recycle the old one. Look here to find a recycling center near you: http://www.rbrc.org/call2recycle/dropoff/index.php Finally, some software resources that you can use to check your battery's status. For Windows: BatteryMon http://www.passmark.com/products/batmon.htm For Macintosh: coconutBattery http://www.coconut-flavour.com/coconutbattery/index.html For Linux: If you've compiled ACPI and power management support into your kernel, have a look at the files in the /proc/acpi/battery/ tree.

williamjones
williamjones

DRidgley, Li-Ion battery manufacturers distinguish between a "full" discharge and a "deep" discharge. This point is covered in the original article. If you discharge a laptop battery to the point that your OS reports no charge and the computer suspends, that's a "full" discharge. At this point, even though the gauge reads zero the battery actually still has some charge left. This reserve charge is built in to allow the laptop to remain suspended for a brief time while you get it connected to power again. A "deep" discharge occurs when the battery's reserve charge is completely used as well. If a laptop is still suspended and it's battery experiences a deep discharge, the computer will power off (without saving its state, I might add). You're absolutely right; a complete, deep discharge will damage your battery. Not much in a single instance, but repeated deep discharges will have a cumulative effect. Battery manufacturers recommend that Li-Ion batteries have regular discharges til their gauge reads zero, though (usually every month, or 30 charge cycles). This helps keep the capacity measurement circuitry in your battery calibrated. I don't know much about Zinc-based or Ni-Cad batteries, so you may very well be right about their discharge needs. My tips were for Li-Ion batteries, since those have mostly replaced other types of chemical batteries in situations where higher voltages are required, like in laptops and other computing devices. Other types of batteries are used in different situations, and are beyond the scope of my original article. As always, a good rule of thumb: read your manufacturers instructions for proper care and maintenance of your equipment.

danarid
danarid

Your clarification of this issue is excellent and would have best been a part of the original article. One wonders if this sort of information, in general, would make out instruments last longer.

williamjones
williamjones

...this is a part of the original article. If the distinction between the two types of discharges wasn't clear, then I appreciate the feedback.