#48B. PurePi II 5V+3.3V ultracapacitor/LifePO4 battery power supply combo with ultracapacitors/battery holders pre-installed

Introduction
PurePi is a compact size audiophile grade dual power supply combo that is specially designed for Raspberry Pi audio applications to improve sound quality. PurePi integrates a 5V ultracapacitor power supply and a 3.3V isolated pure LifePO4 battery power supply together in one PCB. With the spring contacts, it is very easy to install a Raspberry Pi and other audio HATs on top of the PurePi without needing any additional power connectors. PurePi can also be used as a seat base of the whole audio project with anti-vibration spike feet and the possible rubber ring suspensions. PurePi would be very much suitable to build FifoPi or FifoPiMa based Raspberry Pi stream transports, DACs and other audiophile projects.
PurePi is functionally equivalent to a ConditionerPi 5V plus a LifePO4Mini 3.3V.
PurePi II is an improved version over PurePi with some new features.

Features and Specifications

• 5V ultracapacitor power supply with two 100F/2.7V ultracapacitors pre-installed. ESR less than 10mOhm
• 3.3V isolated pure LifePO4 battery power supply with battery holders pre-installed for two 18650 battery cells. ESR less than 6 mOhm. The ultra-low output noise would be only decided by the battery cells.
• Special designed gold-plated spring contacts to power a Raspberry Pi directly to GPIO from the bottom side of PCB without needing any connectors
• Works as a seat base of the whole project. Anti-vibration spike feet can be installed. And the rubber ring suspensions are also possible to be installed.
• Only one standard 5V 2.5A or higher current power supply in USB-C is needed as power input.
• On-board power ON/OFF control switch. This switch can also be extended as an external ON/OFF switch.
• Remote ON/OFF control output signals make it possible to integrate with multi-power supply systems as a group to perform a master on/off control.
• Built-in protection scheme to prevent battery cells from exhausted or low output voltage
• Passive power supply with ultra-low noise and high dynamic current
• Ultra-low ESR MOSFETs controlled by optical isolators to eliminate any possible leakage current
• Built-in active balancers for ultracapacitor protection.
• Low cost but no compromise on performance
• DIY friendly

User's manual

Documents

https://github.com/iancanada/DocumentDownload/tree/master/UltraCapacitorPowerSupply/PurePi

Note:

1. For safety reason, the two 18650 LifePO4 battery cells are not included . They are sold separately but only available for Canada and USA customers.  Must use the 3.2V 18650 LifePO4 type batteries. Standard 3.7V Lithium battery doesn't work.
2. There will be no 3.3V output if LifePO4 batteries are not installed.
3. Customers from the rest of international areas need to source the 3.2V 18650 LifePO4 battery cells by themselves.  You can try Aliexpress or other stores.
4. To working with RaspberryPi 5, have to buy the 6mm M2.5 standoffs. The supplied default standoffs (7mm M2.5) are for Pi4  and other RPis. 
5. Apple USB adapter may not work properly for non-Apple devices, I highly recommend using high quality standard USB power adapters, for example 65W Anker or UGREEN, for PurePi.  If PurePi quits the conditioning mode (D13 turns off), normally it because of a low quality USB power adapter which can not keep higher than 4.9V voltage while deliver high current. Please use a high quality USB power adapter and a shorter cable to solve this issue . Never use USB extension cables. It's highly recommend using a high quality USB-A to USB-C cable (higher current) and connect to the UcPure first and then to the USB power adapter.
6. PurePi is not a UPS, it doesn't work if power input is disconnected.

High quality spike feet are available here

Caution: Batteries and Ultracapacitors can have energy stored once they are installed or charged. So a short circuit can still make damage to the PCB even power switch is turned off or without a power input. Please be very careful no to short circuit in any case or during installation.