How to store a laptop battery properly

June 1, 2012 - PRLog -- A laptop battery can be charged 300-1000 times. The actual number depends on the way it has been treated. In the last post of this series, I outlined the influence that the temperature has on a battery’s lifespan. Today, I will explain how a battery should be charged and discharged with care.

Fully discharge a new battery and then re-charge it. This calibrates the battery.

Calibrate the battery every 30 charges, i.e., fully discharge it and charge afterwards.

low-batteryAvoid frequent full discharges. In contrast to NiCd (Nickel-cadmium) and NiMh (Nickel-metalhydride) batteries, Li-ion (Lithium-ion) batteries show no memory effect. That is, it will do no harm to the battery if it is re-charged before it is empty. Full discharges will strain the battery.



Avoid total discharges. Total discharges, i.e., to the cut-off point, can destroy battery cells. Not all cells in a laptop have the same voltage. Your laptop’s battery gauge only displays the state of the whole battery. If a cell goes below a certain voltage it will be destroyed. Therefore, it is safer to stop working when your battery level reaches 20%. The low battery level can be configured under Vista in the advanced power settings applet. Vista will warn you when the battery reaches the low battery level.

maximum-processor-stateAvoid high discharge rates. High discharge rates also strain the battery. Therefore, I would avoid power intensive tasks while working on battery. Some laptops come with special power management software that can disable unused components. Every piece of hardware that is active produces heat and wastes precious battery capacity. I also recommend checking out Vista’s advanced power management features. You will find many ways to reduce the power consumption. For example, I always set the maximum processor state to 1% while working on battery. You will be surprised at what a modern CPU can accomplish with 1% of its capacity.

Avoid full charges. Fully charged batteries deteriorate faster, especially at high temperatures. Monitor the battery icon in the systray and disable charging before it is fully charged. I guess this is not really a practical advice. Hence, it is only something for battery life-saver enthusiasts.

Dell-disabling-chargingAvoid charging. This might sound like a rather unrealizable piece of advice because an empty battery has to be charged so it can be used again. The problem is that a lithium-ion battery only allows a limited number of discharge/charge cycles. If you are working on main, Windows will try to charge the battery whenever it falls below a certain level. This procedure is the worst thing that can happen to a battery. Usually, power management is set to high performance while the laptop is connected to AC. This increases the heat in the laptop while the batteries are being charged. One option is to disable charging while working on main. A far better option is to remove the battery if you don’t need it for the next couple of days.



Many people believe that low temperatures are harmful for batteries because they think of past winters when their car didn’t start in the morning after a cold night. However, the technology used in car batteries has little to do with Li-ion batteries. The same applies to non-rechargeable batteries, which can even be recharged a little by exposing them to the warm sunlight. The truth about Li-ion batteries is that high temperatures are their worst enemy. Therefore, the following tips will help prevent laptop batteries from getting too warm.

   Always use a laptop on a hard surface. Don’t put it on your lap (despite its name) or on thermal insulating materials such as cushions. If you like to work in bed with your laptop, I recommend using a laptop table. I have this one, and I am quite content with it.
   Try to avoid charging the battery while you are working with the laptop. Charging the batteries increases your laptop’s temperature. The problem is that the CPU, the graphics card and the hard disk also heat up your laptop, which adds to the temperature increase experienced when charging the battery. Many vendors deliver their laptops with software that allows you to disable charging. You also can remove the battery while you are working on AC current.
   Make sure the laptop’s ventilation can always work properly. Don’t place objects before the ventilation systems opening. Don’t run or charge the laptop while it is in its case.
   Don’t leave the laptop in the car or under the sun in summer. Use a bike. It keeps your laptop battery cool and your own battery healthy. And too much sun exposure causes only skin cancer anyway.

While the high temperatures inside modern laptops are probably the worst enemy of a Li-ion battery, frequent discharge/charge cycles will negatively influence a battery’s life. If your laptop is a desktop replacement, then you probably only need the battery every now and then. It can be quite frustrating if you want to use your laptop for the first time after a year without AC, only to realize that your batteries are already dead even though you never really used them. However, if you remove the battery from the laptop and store it accurately, there is a good chance that it will be in good condition when you need it next time.



Don’t store a battery that is almost empty. Stored batteries continue losing energy, albeit at a much slower pace. If the stored battery is totally discharged, it could be destroyed.

laptop-battery-fridgeDon’t store a fully charged battery.Fully charged batteries deteriorate faster than half-charged batteries. Most articles I’ve read recommended storing laptop batteries with a 40–60% charge.

Store the battery at a low temperature. I usually put it in the fridge. It keeps my battery fresh and crisp. Check out this table at Wikipedia. 0°C (32°F) seems to be the best storage temperature. I wouldn’t put the battery in the freezer even though Li-ion batteries only freeze at approximately −40°C.

Store the battery in a dry place. A moist environment will accelerate discharging the battery.

Check the battery state every now and then. I would remove it from the fridge at least every 30 days to calibrate it (fully discharge and charge).

Let the battery warm up a little before you put it back into your laptop. If the temperature is raised too fast, it will strain the battery.

When I started this article, I thought I’d just share a few tips I’ve found on the web. But then I realized that there are quite a few things that can be done wrong with laptop batteries. That’s how I ended up with three articles. It is quite amazing that we can build space ships that have enough energy to fly to the moon but still have no decent portable energy sources for simple laptops. Perhaps fuel cells will change the picture in a few years.