Power management for Laptops

Batteries & power management Nickel Cadmium (Ni-Cd) Nickel-Metal Hydride (Ni-MH) Lithium-Ion (Li-Ion)

Nickel Cadmium Biggest problem Battery Memory. Losing a significant amount of battery life when repeatedly recharging without completely draining.

Nickel-metal Hydride Still susceptible to Battery memory Still susceptible to heat Can take more recharges

Lithium-Ion No longer susceptible to Battery memory. Last twice as long as Nickel-metal Cannot handle as many charges as Nickel Cadmium (sacrifice life span for length of time) Lithium-Ion batteries will explode if over charged.

Care of batteries & storage Store batteries in cool place & keep batteries at 70-80% Never drain batteries all the way to 0% Remember that a rechargeable batteries has a limited number of recharge/ discharge times

Power management on Notebooks Every part of a laptop uses power Earlier laptop used to much power for each individual part constantly draining the batteries They needed a way for you system to go into a hibernation type mode.

System manage mode (SMM) Intel began development of a possessor to handle power management CPU clock speed to slow down or stop without losing running state Power save mode Collectively they were called SMM Was not enough (you need a BIOS & OS that could fully utilize the SMM modes) BIOS & OS utilization Intel sent out specifications for APM & ACPI APM Advanced Power Management APCI Advanced configuration and power interface

Requirements on APM/ACPI Need SMM powered CPU Need APM compliant BIOS Enables the CPU to shut off peripherals when desired It also need an OS system that know how to request particular devices to be shut down and to ask for the CPU clock to be slowed or stopped ACPI (successor to AMP) ACPI and allows user the ability to manage hot swappable items

APM Levels Full on (power connected) APM enables (power disconnected but batteries at full charge) CPU and RAM are being watched / none used devices may be disabled APM Standby CPU is stop and RAM stores all programs all devices are turned off APM Suspend Everything on PC is shut down to save power consumption Critical information is written to the hard drive (typically know as your hibernation state)

ACPI Levels G0- Fully operational G1 - into sleep stage mode S1 CPU stop processing but power to both ram and CPU stay the same S2 CPU is shut down S3 Standby mode is enabled RAM stays with power S4 Hibernation mode is enabled RAM information is stored to HDD G2 or S5 All components turn off except for USB keyboard or mouse G3 everything is shut off except for the RTC which is the Real time clock and all components are powered down.