Anyone know about lithium-ion batteries for laptops?

[Genecks]

I haven't read articles about lithium-ion batteries in a while, but I continue to think they are biased. Sometimes things just say to me, "Manufacturers trying to manipulate people like CNET."

 

I have read articles that state review editors were given batteries that were twice as long or just very different from what has/was regularly sold in a store. If not for CNET, then many other websites.

 

So, I've felt for the past few years that knowledge about lithium-ion batteries for laptops has been biased.

 

I'm wondering if anyone here has any scientific knowledge about these things, the proper way to maintain them, and research that has been conducted.

 

I've found various articles on the web that conflict.

 

Some say to charge the battery all the way when you're done.

 

3. Rechargeable batteries undergo self-discharging when left unused. Always store a battery pack in a fully charged stage for storage.

 

http://www.laptop-battery.org/batterytips.html

 

Other articles say to keep a batter charged at 40% to 50%.

 

http://mobileoffice.about.com/od/usingyourlaptop/f/laptopbattery1.htm

 

The idea of keeping a batter at half-charge sounds silly if the point of the battery is having it last its full-time charge at best.

 

Also, do not let a Li-On battery completely discharge. (Discharing is only for older batteries with memory effects)

 

http://www.friedbeef.com/2007/07/01/top-15-ways-to-extend-your-laptop-battery-life/

 

It seems like the knowledge provided by various websites tends to conflict. So, does anyone know the science behind these things and proper maintenance based on their chemical, electrical, and physical properties?

 

Not to be elitist, but for all I see, this stuff is speculation. I don't see much information sourced anywhere in the website discussing Li-Ion battery technology.

Edited October 21, 2008 by Genecks

[Glider]

I haven't read articles about lithium-ion batteries in a while, but I continue to think they are biased. Sometimes things just say to me, "Manufacturers trying to manipulate people like CNET."

 

I have read articles that state review editors were given batteries that were twice as long or just very different from what has/was regularly sold in a store. If not for CNET, then many other websites.

 

So, I've felt for the past few years that knowledge about lithium-ion batteries for laptops has been biased.

 

I'm wondering if anyone here has any scientific knowledge about these things, the proper way to maintain them, and research that has been conducted.

 

I've found various articles on the web that conflict.

 

Some say to charge the battery all the way when you're done.

 

3. Rechargeable batteries undergo self-discharging when left unused. Always store a battery pack in a fully charged stage for storage.

 

http://www.laptop-battery.org/batterytips.html

This is not true for Li Ion batteries. In short, the greater the charge (before storage), the faster the discharge. Imagine a cup of coffee. A very hot cup of coffee will cool faster than a cooler cup of coffee due to the steeper temperature gradient (potential).

 

 

Other articles say to keep a batter charged at 40% to 50%.

Yes, this is true. A charge of around 40% will result in a slower discharge rate.

 

The idea of keeping a batter at half-charge sounds silly if the point of the battery is having it last its full-time charge at best.

Not really. The idea is to slow the discharge rate to a point that the battery can be stored for long periods without risk of complete discharge, which is the worst thing that can happen to a lithium ion battery.

 

It seems like the knowledge provided by various websites tends to conflict. So, does anyone know the science behind these things and proper maintenance based on their chemical, electrical, and physical properties?

 

Not to be elitist, but for all I see, this stuff is speculation. I don't see much information sourced anywhere in the website discussing Li-Ion battery technology.

A lot of kit (cell phones, laptop etc.) manufacturers provide minimal information regarding battery care. Some haven't changed the information since they used Nickel Metal Hydride or cadmium batteries.

 

Lithium ion batteries are very cool (IMO). They have no memory effect (a major advantage) so they never need complete disharging (which should be avoided. It's very bad for Li-Ion batteries to do that).

 

However, a lot of kit comes with a battery meter (like a fuel gauge). A major advantage of Li-Ion batteries is that you can charge them whenever you feel like it, even if they're not discharged. In fact, Li-Ion batteries prefer frequent partial top-ups and last longer using them. These partial charges do not count as full charge-discharge cycles and so you can do that many more times than the 300 full cycles most are rated for. My PDA battery is still going strong after more than 5 years!

 

However, these partial charges put the battery out of synch with the battery metres (they lose calibration) and so every now and again, it's good to let the battery run down through normal use to the point the battery metre reads full discharge and the kit shuts down. In fact the battery will not be fully discharged. Kit designed for use with Li-Ion batteries is designed to shut down when the battery reaches around 1/3 - 1/4 charge. This is to avoid complete discharge which, as I say, is the worst thing you can do to a Li-Ion battery.

 

As for storing them; I store mine at 40-50% charge, in the fridge (at between 0 - 4 degrees C). Temperature is another factor in Li-Ion battery performance. They don't like high temps. Further, the lower the temp for storage, the slower the discharge rate and the more recoverable capacity when required for use (down to a minimum of 0 degrees, don't actually freeze them, that's not good).

 

It's usually also best not to buy a 'spare' battery for Li-Ion kit. Li-Ion batteries begin to age as soon as they're made (other types begin only after their first charge). Only buy a new battery when the original loses capacity (won't fully re-charge). There are some exceptions, for example, I carry a 'spare' for my camera. But that's because, depending on the situation, it's quite possible to flatten a battery before the photo opportunities are over (particularly if I'm out for a weekend), even though I can get around 500 to 600 shots from one charge. Also, if it's a cold winters' day, the batteries will perform less effectively, which means I can carry one in my pocket (to warm it up) and one in the camera (until it cools down too much) and just A-B them to keep shooting.

 

This is less necessary with a cellphone or other kit, but I do accept that my spare won't be able to take over from my original like a new battery would. In fact, I try to A-B them so it's more like using one double-capacity battery. They go in the fridge at 40% charge whenever I'm not using them for more than a couple of weeks.

 

Here are a couple of articles that might be of interest to you: How to prolong lithium based batteries and How to store batteries. I hope this is of use.

Edited October 21, 2008 by Glider