1. General information about lithium-ion battery.
Nowadays, lithium-ion battery is the fastest growing battery system and most popularly used in laptops. To get some idea about this battery is essential for all our customers:
a. Advantages
 High energy density - potential for yet higher capacities.
Does not need prolonged priming when new. One regular charge is all that's needed.
Relatively low self-discharge - self-discharge is less than half that of nickel-based batteries.
Low Maintenance - no periodic discharge is needed; there is little memory.
Specialty cells can provide very high current to applications such as power tools.
b. Limitations
Requires protection circuit to maintain voltage and current within safe limits.
Subject to aging, even if not in use - storage in a cool place at 40% charge reduces the aging effect.
Transportation restrictions - shipment of larger quantities may be subject to regulatory control. This restriction does not apply to personal carry-on batteries.
 Expensive to manufacture - about 40 percent higher in cost than nickel-cadmium.
Not fully mature - metals and chemicals are changing on a continuing basis.
2. How to charge lithium-ion battery?
a. Should I charge my battery partially or fully?
Does not matter. Charging in stages is acceptable. Full charge termination occurs by reading the voltage level and charge current. Charging a full battery is safe and does not cause harm.
b. Should I remove the battery from the charger when full?
It does not matter. The charger automatically cuts the charge current when the battery is full.
c. Should the battery be kept charged when not in use?
Best to store at 40% charge or 3.75-3.80V/cell open terminal. Cool storage is more important than state-of-charge. Do not fully deplete battery because Li-ion may turn off its protection circuit.
d. What are the allowable charging temperatures?
Important: Rechargeable batteries can be used under a wide temperature range, this does not automatically permit charging at these extreme conditions. Generally the best charging tempreature is 5C° - 45°C (41°F - 113°F), or else the temperature sensor may prevent charge or cut off the charge prematurely.
e. What should I know about chargers?
Charger should apply full charge. Avoid economy chargers that advertise one-hours charge. Fastest full-charge time: 2-3 hours.
3. Discharging at high and low temperature：
Lithium-ion works within the discharge temperature limits of -20°C to 60°C (-4°F to 140°F). The performance is temperature based, meaning that the rate capability at or below -20°C is reduced due to the increased impedance of the electrolyte. Discharging at low temperatures does not harm the battery. Lithium-ion may be used down to -30°C (-22°F) with acceptable results. Larger packs will be necessary to compensate for the reduced capacity at these temperatures.
It is not recommended to discharge lithium-ion at temperatures above 60°C. A high discharge rates combined with elevated temperatures can cause self-heating, an effect that could permanently damage the separator and electrodes of the cells.
4. Laptop battery safety concerns:
A major concern arises if static electricity or a faulty charger has destroyed the battery's protection circuit. Such damage can permanently fuse the solid-state switches in an ON position without the user knowing. A battery with a faulty protection circuit may function normally but does not provide protection against abuse.
Another safety issue is cold temperature charging. Consumer grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the packs appear to be charging normally, plating of metallic lithium occurs on the anode while on a sub-freezing charge. The plating is permanent and cannot be removed. If done repeatedly, such damage can compromise the safety of the pack. The battery will become more vulnerable to failure if subjected to impact, crush or high rate charging.
5. WARNING when charging lithium-ion cells and packs:
a. Never connect cells in parallel and/or series that are not designed for that purpose. A cell mismatch may cause overcharge and venting with flame.
b. Never charge or discharge the battery without connecting a working protection circuit. Each cell must be monitored individually and the current disconnected if an anomaly occurs.
c. Always attach a temperature sensor when charging and discharging the battery. The temperature sensor must disconnect the current on excess temperature.
d. Only connect cells that are matched and have the identical state-of-charge.
e. Pay special attention when using an unknown brand. Not all brands contain intrinsic safety features that protect the cell when stressed.
f. During experiments, place the test battery into a well-ventilated fireproof container.
g. Never leave the battery unattended while under charge or discharge.
h. Do not charge a battery hat has physical damage.
6. How to prolong & store batteries?
While capacity loss during a battery's life cannot be eliminated, simple guidelines minimize the effect:
Keep batteries in a cool and dry storage area. Refrigeration is recommended but freezers should be avoided. When refrigerated, the battery should be placed in a plastic bag to protect against condensation
Do not fully charge lithium and nickel-based batteries before storage. Keep them partially charged and apply a full charge before use. Store lithium-ion at about 40% state-of-charge (3.75-3.80V/cell open terminal).
Always store a lead acid battery in full-charge condition. Observe the open terminal voltage and recharge the battery every 6 months or as recommended by the manufacturer.
Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory. (In this respect, lithium-ion differs from nickel-based batteries.) Short battery life in a laptop is mainly cause by heat rather than charge / discharge patterns.
Do not store lithium-ion fully depleted. If empty, charge for about 30 minutes before storage. Self-discharge on a depleted battery may cause the protection circuit to trip, preventing a recharge.
If you have a spare lithium-ion battery, use one to the fullest and keep the other cool by placing it in the refrigerator. Do not freeze the battery. For best results, store the battery at 40% state-of-charge. |
