hi. i got some notes on how to preserve li-ion batteries. this matter caught my attention when i read a thread about incorrect charging methods for Li-Ion batteries.

http://forum.lowyat.net/topic/672760

if you have any questions or wish to add some info or correct any or my statements, by all means, please pm me. i'm glad to be of help and even happier to learn new stuff.

Anyway, I believe this is quite an important aspect since our handphones and notebooks are powered by Li-Ion batteries. To check what type of battery you are using, just remove the battery and checkout the sticker. Of course, dont forget to turn off your equipment first.

The type of battery, voltage output and maximum current is written on that sticker. If you have a battery without any sticker or printings, the sticker may have fallen off OR you bought a really cheap battery. Note, that is pretty dangerous to your equipment. It may be cheap but unstable voltage or current will degrade your experience and seriously affect the performance of your equipment. Hope you find this guide useful

Types of Rechargeable Batteries
There are 2 main types of rechargeable batteries used with electronic devices: Nickel based and Li-ion batteries. NiMH (older batteries) are prone to memory effect while Li-Ion batteries do not have any memory effect. If you are using NiMH or NiCad (nickel based) batteries, then you will have to worry about memory effect. Most modern batteries are made out of Li-ion and therefore do not suffer memory effect. This guide does not cover your liquid-filled batteries, such as your sulfuric acid car battery.

Memory Effect
Memory effect is an effect that occurs after a series of charging and discharging whereby the battery does not charge up to 100%. It would assume that the charge is full even though it is much less than that. For Nickel based batteries, you'll have to fully discharge it before charging to avoid memory effect. Li-ion batteries, on the other hand are not affected by full discharge.

Good Charging Practice
For Li-Ion batteries, do not do practice full discharge and full recharge often. Unlike Nickel batteries, this practice will damage and shorten the life-time instead. Li-Ion batteries prefers trickle charge or normal charging when it drops to about 70%-80%.

There are some myths about Li-ion batteries experiencing memory effect. This is not true. Over time, the practice of partial recharge or trickle charge, would "confuse" the charging and sensing system. As such, calibration to the sensing system would be needed or the charging meter would indicate a wrong battery status. This is sometimes known as the "digital" memory effect and does affect the battery cells. To avoid this, it would be a good idea for a full-discharge after 30 charges to calibrate the battery meter.

Additional Note
1. Trickle charging is the best for Li-Ion. Minimize full discharge/recharge cycles. However, trickle charging is dangerous if the charger does not monitor the voltage levels correctly. This may lead to overcharging.

2. Do not overcharge. Normally, your charger will monitor the charging. If, by any chance that the charger is faulty and overcharges, the battery cell will be permanently damaged.

3. Minimize deep discharge (over discharge). Li-Ion batteries are not meant for deep discharge.

4. It is good to maintain the battery cool. This prevents aging of the battery cells.

Trickle charging is an intelligent charging circuit that charges the battery around the rate of self discharge. Imagine having a "smart" water tap that monitors the water level in a leaking bucket. The water tap opens occasionally about the same rate as the water is leaking. This prevents the water level from dropping too low, or over flowing. Apply that same concept to the battery charging circuit.

Additional Links
1. http://en.wikipedia.org/wiki/Memory_effect
2. http://forum.notebookreview.com/showthread.php?t=91846
3. http://www.batteryuniversity.com/parttwo-34.htm
4. http://www.laptopbattery.net/laptopbattery_chemistry.html
5. http://en.wikipedia.org/wiki/Battery_charger
6. http://en.wikipedia.org/wiki/Trickle_charging

-------- Q & A from forumers in LYN--------

Can u tell me best practice on handling new li-ion batt?I heard one must charge new batteries for 8 hours before using it.Is dat true?


If i don't remove the battery from my notebook while using ac adapter, will it cause damage to the battery? Im using the Li-ion type of battery.

Regarding the overcharged issue, if i charge my battery overnight during my bedtime, will the ac adapter automatically stop the charging progress for me after the battery is completely charged?



Are these statements true?

Q Should I totally discharge, then recharge my Dell laptop battery occasionally to make it last longer?
A No, discharging and charging does not increase the life of a Lithium Ion technology battery.

Q Can a Dell laptop battery be "overcharged"?
A No, the battery is designed to stop using the charger when it reaches full charge.

Q When docked or AC adapter is plugged into a wall outlet, am I using my battery charge?
A No.

source: http://www.dell.com/content/topics/global....n/batteries_faq



This post has been edited by Nezs: Oct 7 2009, 12:15 AM