MULS B21N1818-3 C21N1818-3 Laptop Battery for Asus Vivobook A409M A409J

About MULS
1. We have professional battery and adapter experience!
Strictly test before shipment to ensure full capacity and safety without harming the computer!
2. We recommend that the first charge is not less than 5 hours.
3. The new battery cannot be charged, is there a problem with the battery?
Usually not. The computer charges the battery for the first time. Due to the instability of voltage and current, the computer may stop charging the battery when the battery is half charged (sometimes more, sometimes less). If this happens, Don't worry, just take the battery out of the computer and recharge it again. The new battery charged for the first time may require several iterations. Don't worry, this is normal.
4. When the battery is in normal operation, if the battery is discharged to 3%, it must be shut down or recharged. If the battery is discharged to 0%, the battery will be damaged and its life will be attenuated.
5. Avoid falling, heating, and short-circuit, avoid using the battery in an environment where the temperature is too high or too low.
Specification:

Voltage: 7.7V
Capacity: 37Wh
Condition: Brand new from the manufacturer, Grade A cell
Replacement for Part Number
B21N1818-3 C21N1818-3
Compatible Laptop Models:

Fit for Asus VivoBook 14 A409 A409DA A409M A409MA A409F A409FA A409FB A409FJ A409J A409JA A409JB F409UB M409 M409B M409BA M409D M409DA M409DJ X409 X409M X409MA X415 X415D X415DA X415DAP X415E X415EA X415EP Series;
Fit for Asus VivoBook 14 X415F X415FA X415FAC X415J X415JA X415JAB X415JP X415M X415MA D415 D415D D415DA D415U D415UA M415 M415D M415DA M415U F415M F415MA A415 A415E A415EA A415J A415JA A415D A415DA Series;
Fit for Asus VivoBook 15 X545 X545FA X545FB X545FJ Series;
Fit for Asus VivoBook 15 R545 R545F R545FA R545FB R545FJ Series;
Fit for Asus VivoBook 15 A509 A509DA A509M A509MA A509F A509FA A509FB A509FJ A509J M509B M509BA M509D M509DA M509DJ F509 F509DA F509J F509JA F509JB F509F X509FJ X509FL X509JP X509M X509MA D515 D515D D515DA D515U D515UA M515 M515D M515DA M515U M515UA F515 F515E F515EA F515J F515JA F515M F515MA Series;
Fit for Asus VivoBook 15 A515 A515E A515EA A515EP A515J A515JA A515D A515DA S515 S515E S515EA S515J S515JA S515D S515DA X515 X515D X515DA R565M R565MA ASUS VivoBook 15 X545 X545FA X545FB X545FJ Series.
Note: Please open the back cover of your laptop to check the original battery size and capacity before placing an order.
1. Turn off your laptop and disconnect the power.
2. Disconnect the connection between the old battery and the motherboard to avoid unnecessary damage caused by disassembling the battery. Then unscrew the old battery screws one by one and carefully save each screw.
3. Remove the old battery, carefully connect the new battery to the mainboard, reinstall all the parts that have been removed earlier, and connect the wiring of the new battery.
4. If you don't understand the above steps, you can search the relevant installation tutorial video on YouTube for help.
1. New battery: Discharge the new battery to 10% (not 0%), then charging up to 95% and repeat 3-4 times to activate the maximum capacity.
2. Overuse: Do not always run out of a battery to 0%, that would damage the battery or shorten the usage life.
3. Charging sequence: when charging, first install the battery, then turn on the power, when fully charged, first cut off the power, then pull the power plug.
4. Fully charge the battery before long-term storage, and keep charging once a month.
Do not store the battery at low power circumstances.

Could be caused by battery loose. Please re-install the battery and make sure that the battery cable and the motherboard interface are tightly inserted.
Maybe due to conductive material damaged which the laptop motherboard and battery anode and cathode contact position, you can try to confirm it with your ori