The AC adapter and battery must be plugged in before the system bios can be flashed" - Dell Community
![Dell Inspiron 1520 1720 1721 1521 1270 3pin BIOS CMOS RTC Internal Clock Battery 6070126132965 | eBay Dell Inspiron 1520 1720 1721 1521 1270 3pin BIOS CMOS RTC Internal Clock Battery 6070126132965 | eBay](https://i.ebayimg.com/images/g/ZI4AAOSw14Zd5Tno/s-l500.png)
Dell Inspiron 1520 1720 1721 1521 1270 3pin BIOS CMOS RTC Internal Clock Battery 6070126132965 | eBay
![Rome Tech CMOS Battery for DELL Inspiron 1520 1521 1720 1721 1500 - Laptop Backup BIOS RTC 3V CR2032 Battery with 3 Wire Cable Rome Tech CMOS Battery for DELL Inspiron 1520 1521 1720 1721 1500 - Laptop Backup BIOS RTC 3V CR2032 Battery with 3 Wire Cable](https://m.media-amazon.com/images/I/619eXXIp3nL._AC_UF350,350_QL80_.jpg)
Rome Tech CMOS Battery for DELL Inspiron 1520 1521 1720 1721 1500 - Laptop Backup BIOS RTC 3V CR2032 Battery with 3 Wire Cable
The AC adapter and battery must be plugged in before the system bios can be flashed" - Dell Community
![Amazon.com: Replacement CMOS Battery for DELL Inspiron 1318 1720 1721 Vostro 1400 1500 1700 XPS 15 L501X Precision M2400 M4400 M6500 Backup Reserve Button Cell Batteries 3 Pins 3 Wires : Electronics Amazon.com: Replacement CMOS Battery for DELL Inspiron 1318 1720 1721 Vostro 1400 1500 1700 XPS 15 L501X Precision M2400 M4400 M6500 Backup Reserve Button Cell Batteries 3 Pins 3 Wires : Electronics](https://m.media-amazon.com/images/I/61RsuM7UCfL._AC_UF894,1000_QL80_.jpg)
Amazon.com: Replacement CMOS Battery for DELL Inspiron 1318 1720 1721 Vostro 1400 1500 1700 XPS 15 L501X Precision M2400 M4400 M6500 Backup Reserve Button Cell Batteries 3 Pins 3 Wires : Electronics
![Rome Tech CMOS Battery for DELL Inspiron 1520 1521 1720 1721 1500 - Laptop Backup BIOS RTC 3V CR2032 Battery with 3 Wire Cable Rome Tech CMOS Battery for DELL Inspiron 1520 1521 1720 1721 1500 - Laptop Backup BIOS RTC 3V CR2032 Battery with 3 Wire Cable](https://m.media-amazon.com/images/I/51LocyfM+rL._AC_UF350,350_QL80_.jpg)
Rome Tech CMOS Battery for DELL Inspiron 1520 1521 1720 1721 1500 - Laptop Backup BIOS RTC 3V CR2032 Battery with 3 Wire Cable
![Update install BIOS forcefully without Battery / damaged battery or battery below 10% in Dell Laptop - YouTube Update install BIOS forcefully without Battery / damaged battery or battery below 10% in Dell Laptop - YouTube](https://i.ytimg.com/vi/c7tw3Xns5S8/maxresdefault.jpg)
Update install BIOS forcefully without Battery / damaged battery or battery below 10% in Dell Laptop - YouTube
![Synergy Digital CMOS/BIOS Battery, Compatible with Dell Inspiron 1720 CMOS/ BIOS, (Lithium, 3V, 200mAh) Ultra High Capacity, Replacement for Dell 23.22056.001, CB28 Battery - Walmart.com Synergy Digital CMOS/BIOS Battery, Compatible with Dell Inspiron 1720 CMOS/ BIOS, (Lithium, 3V, 200mAh) Ultra High Capacity, Replacement for Dell 23.22056.001, CB28 Battery - Walmart.com](https://i5.walmartimages.com/asr/5d569a77-ab4a-421e-b52b-376dfe79bad4.c8474fc91aa56beec3d9fb3924fb7053.jpeg)