Friday, August 7, 2009

How to measure the power consumption of notebook battery

All the battery spec info are from Laptop battery

How to measure the power consumption of notebook battery

The Original article posted in

Why laptop battery capacity reduce as time? Why battery calibration can improv battery capacity? How to charge the battery correctly? All above probelm are related to battery power consumption. Open circuit voltage measurement ... ... Coulomb measurement, impedance measurement, what are these terms mean? Here we will simply introduce all of them!

Whether it is the out nickel-metal hydride batteries, lithium-ion Dell laptop battery, or not commonly used lithium polymer batteries, and even coming silver zinc batteries, are equivalent to the a storage warehouse of electronic power. The differences between them is that the way out of the Treasury, the volume of stocks it. In laptop batteries, there is a power manage center - power consumption chip, it is the management of power measuring, charging and discharging managing.

In the measurement of battery technology, there are four kinds common method (open-circuit voltage measurement, Coulomb calculation, impedance measurement, integrated look-up table method), but not all IBM laptop battery used only one method, usually using a combination of methods to one of the main method of supporting the rest of the way computing power. The first one is the open circuit voltage measurement, this method is that measuring the battery voltage under static values to calculate the remaining battery capacity, but as a result of stationary lithium-ion battery voltage and remaining capacity relation is non-linear, so this method measured valueis not accurate, the vast majority of mobile phone batteries are calculated using this method;

The second one is Coulomb calculation, the method is by measuring the laptop battery charge and discharge current, the current value and time value After the calculation of product integration has been carried out by filling the battery into the power and the release of electricity, Coulomb's method is a accurate method of calculating power;

The third one is the impedance measurement, measuring its resistance to get the remaining battery capacity value; the fourth is a comprehensive look-up table method, by setting up a related form, the voltage, current, temperature and other parameters, you can query the remaining battery capacity.

Therefore, in addition to the internal structure of the battery batteries, there are control chips, the chip which contains 1-2 kinds of batteries power measurement method of calculation, and a charge-discharge protection circuit. HP laptop battery manage program had been setted in the system, and through access to the chip-driven interface, and then set on the battery management.

So, why the Toshiba laptop battery will become weak, but the battery calibration can improve the battery capacity? Notebook battery 6-cell and 4-cell, means that there are a number of battery cells inside the battery. The batteries cells conenect together, the battery capacity reduce reason is that: all the batteries quality and discharge rate can not be in the same level. After discharge, one battery cell capacity in substantial reduction, in order to maintain voltage stability, the battery management chip will be according protection of core power as the "bucket principle", so after the electricity charge will decrease.

Battery calibration is to balance the multiple batteries cells, the Apple laptop battery cells own internal resistance can not be completely consistent, the large internal resistance battery will shoulder the larger current, and its own consumption more than the other batteries. So regular battery calibration is necessary - it can balance the burden of multiple batteries work and prolong the whole battery life.

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