Amazon.com: Synergy Digital CMOS/BIOS Battery, Works with IBM ThinkPad T43 CMOS/BIOS, (Li-Ion, 3V, 200 mAh) Ultra High Capacity, Compatible with Evesham 02K6541 Battery : Electronics
10Pack RTC CMOS Battery for IBM Thinkpad T40 T41 T42 T43 T41p T42p T43p CR2032 | eBay
RTC BIOS CMOS Battery for IBM Thinkpad T40 T41 T42 T43 T41p T42p T43p 02K6572 | eBay