Size and Capacity: Rechargeable 3.7V 800 mAh Li-ion Battery, compatible with Philips HX8900 HX9100 HX9900 series electric toothbrush When To Replace: When you notice that your toothbrush runs out of power quickly after been fully charged, it means the battery has reached its lifespan, you will need to replace a new battery Problem: If your toothbrush is not responding and not charging at all, it means the PCB or motor of your toothbrush has been damaged, it won't help to repair with battery change. We have explained above how the aged rubber seal could let the water seep into the handle and further to damage the internal structure Installation: All our batteries are checked and tested before shipping. Please follow our installation guide QR code to complete the installation.This premium quality battery with long pins allow easy insertion and fit perfectly to the circuit board holes Remarks: Our technician recommend you to change rubber seal regularly, every 3 month to prolong the service life of your toothbrush, motor and battery. To replace the battery you may need to replace the rubber seal depends on the method of installation and toothbrush series Applicable models
Our battery toothbrush compatible with philips sonicare toothbrush,include below models
HX8900 series：8910/8920/8911/8962
HX9100 series：9112/9120/9140/9141/9150/9160/9172/9182/9192
HX9900 series：HX9903/9924/9954/9984/992/993

HX number is marked on the bottom of your toothbrush handle.
For example, HX91series, including HX9120, 9140,9150,9160 and if your handle shows numbers as HX9120/02, they are all HX91 series, the 2-4 digits behind HX91 only refer to exact model, color of the handle or this was sold as package.