[EVO 4G Android Development] cbkham:
thank you MS!!

I would like to say thank you MS also!!! Don't let this keep you down.

The EE engineer guy need to go back to school and do more research on battery technology.

I have fact that it is safe:

Safety requirementsIf overheated or overcharged Li-ion batteries may suffer thermal runaway and cell rupture.[47] In extreme cases this can lead to combustion. Deep discharge may short-circuit the cell, in which case recharging would be unsafe.[48] To reduce these risks, Lithium-ion battery packs contain fail-safe circuity that shuts down the battery when its voltage is outside the safe range of 3–4.2 V per cell.[24][36] When stored for long periods the small current draw of the protection circuitry itself may drain the battery below its shut down voltage; normal chargers are then ineffective. Many types of lithium-ion cell cannot be charged safely below 0°C.[49]

Other safety features are required in each cell:[24]

shut-down separator (for overtemperature)

tear-away tab (for internal pressure)

vent (pressure relief)

thermal interrupt (overcurrent/overcharging)

These devices occupy useful space inside the cells, add additional points of failure and irreversibly disable the cell when activated. They are required because the anode produces heat during use, while the cathode may produce oxygen. These devices and improved electrode designs reduce/eliminate the risk of fire or explosion.

These safety features increase costs compared to nickel metal hydride batteries, which require only a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.[36]

[edit] Specifications and designSpecific energy density: 150 to 250 W·h/kg (540 to 900 kJ/kg)[1]

Volumetric energy density: 250 to 530 W·h/l (900 to 1900 J/cm³)

Specific power density: 300 to 1500 W/kg (@ 20 seconds and 285 W·h/l)[1]

Because lithium-ion batteries can have a variety of cathode and anode materials, the energy density and voltage vary accordingly.

Lithium-ion batteries with a lithium iron phosphate cathode and graphite anode have a nominal open-circuit voltage of 3.2 V and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide cathode with graphite anodes have a 3.7 V nominal voltage with a 4.2 V max charge. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less. Some lithium-ion varieties can reach 90% in as little as 10 minutes.[50]

[edit] Charging procedureStage 1: Apply charging current until the voltage limit per cell is reached.[51]

Stage 2: Apply maximum voltage per cell limit until the current declines below 3% of rated charge current.[51][unreliable source?]

Stage 3: Periodically apply a top-off charge about once per 500 hours.[51][unreliable source?]

The charge time is about three to five hours, depending on the charger used. Generally, cell phone batteries can be charged at 1C and laptop-types at 0.8C, where C is the current that would discharge the battery in one hour. Charging is usually stopped when the current goes below 0.03C but it can be left indefinitely depending on desired charging time. Some fast chargers skip stage 2 and claim the battery is ready at 70% charge.[51][unreliable source?] Laptop battery chargers sometimes gamble, and try to charge up to 4.35 V then disconnects the battery. This helps to compensate for the battery's internal resistance and charges up to 100% in short time.

Top-off charging is recommended when voltage goes below 4.05 V/cell.[51][unreliable source?]

Lithium-ion[which?] cells are charged with 4.2 ± 0.05 V/cell, except for military long-life cells where 3.92 V is used for extending battery life. Most protection circuits cut off if either 4.3 V or 90 °C is reached. If the voltage drops below 2.50 V per cell, the battery protection circuit may also render it unchargeable with regular charging equipment. Most battery protection circuits stop at 2.7–3.0 V per cell.[51][unreliable source?]