Browse Prior Art Database

Economical Charge to Extend Battery Life

IP.com Disclosure Number: IPCOM000015207D
Original Publication Date: 2002-Jan-28
Included in the Prior Art Database: 2003-Jun-20
Document File: 5 page(s) / 158K

Publishing Venue

IBM

Abstract

Abstract: This ECO-Charge application achieves to extend battery life for two tor three times of normal charge condition with no modification of hardware. background:

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Economical Charge to Extend Battery Life

Abstract:

This ECO-Charge application achieves to extend battery life for two tor three times of normal charge condition
with no modification of hardware.

background:
·This Economical charge (ECO-Charge) is related idea to Peak Shift Method patent (DOCKET NO.·: JP9-2001-0016). Fig 1, shows one typical example of Charge discharge cycle at Peak Shift Operation. Battery is discharged during 1PM to 4PM to reduce AC dissipation power.

実測値(ThinkPad T20)

Battery C apacity

Fig 1. Actual Power and Battery capacity at Peak Shift Operation.

This discharge action will be performed 5 working day per week. It will reduce total battery capacity due to cycle life.

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Li-Ion C apacity D ecrease at Full C harge and P eak S hift M ode

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Capacity D ecrease

Fig 2. Li-Ion capacity decrease at peak shift operation

Customer do not want to reduce battery capacity and use longer run time as possible. There are many action was taken ThinkPad charge /discharge system and utilities. as follows,

····Action for ThinkPad Battery Life Extension

Improve Cell Performance Optimized Cell Layout for Thermal Imbalance Charge Current Limitation Charge Voltage (4.20V) Tolerance and Adjustment Trickle Charge Current Adjustment Recharge Flag of 95%

But pay attention to office application ThinkPad battery which is always 100% . This is basic understanding that fully charged Li-Ion battery decreases capacity. Fig 3 shows cycle capacity decreases by each charge voltage. Higher charge voltage shorten the battery life. Lower charge voltage extend battery life. Adequate charge voltage is so selected to be cycle life as 500 cycles to satisfy one year battery warranty.


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Fig 3 Li-Ion Cycle Life and Capacity

Body:

There is fuel gauge circuit provided to intelligent battery pack which is commonly used as ThinkPad battery. Voltage, current remained capacity and other information is communicated between system and battery. (Fig. 4)

CHGDCHG001.DAT (SYD2#21)

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Fig 4. Fuel Gauge data of intelligent battery

This idea use these useful battery data and control charge capacity before 100% charge. For example, about 70% of capacity charged then it wil...