UPS HAT (B) for --Uninterruptible Supply designed for series, compatible with 3 / 3B+ / 4B, etc. pogo pins connector,Powering the via pogo pins, without using any GPIO resource. Uninterrupted Supply --Support simultaneous charging and discharging.It is able to charge the batteries and provide output at the same time from external supply. Automatically switch over to batteries output if external supply is unavailable, keeps the system running without any trouble Real Time Monitoring --I2C bus communication, monitoring the batteries voltage, current, , and remaining capacity in real time. When the voltage dips too low, it is possible to save files properly and then shutdown the system by software, to avoid any data loss. Safe and Stable Circuit Design --Multi battery protection circuits: over charge/discharge protection, over current protection, short circuit protection, and reverse protection, along with the equalizing charge feature, more safe and stable. 5V USB Output As Well --5V USB output, convenient for powering other boards. Onboard 5V regulator, up to 5A continuous output current, more sufficient source for .Battery warning indicators:easy to check if the battery is connected correctly Features Designed for series, compatible with 3 / 3B+ / 4B, etc. I2C bus communication, monitoring the batteries voltage, current, , and remaining capacity in real time Multi battery protection circuits: over charge/discharge protection, over current protection, short circuit protection, and reverse protection, along with the equalizing charge feature, more safe and stable Onboard 5V regulator, up to 5A continuous output current, more sufficient source for 5V USB output, convenient for powering other boards Batteries warning indicators, easy to check if the battery is connected correctly Specifications Output voltage : 5V Charger: 8.4V 2A Control bus: I2C Dimensions : 56 x 85mm Battery support: 2x 18650 Li batteries (NOT included) Mounting hole size : 3.0mm Plug Type:EU Plug,it applies to Indonesia, Germany, France, Spain, Italy and so on Material: PCB colour: blue+black Package Contents: 1 x UPS HAT (B) 1 x 8.4V battery charger 1 x Acrylic protection panel 1 x Screws pack Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.