#48B. PurePi II2026 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.
Functionally it is equivalent to a ConditionerPi 5V plus a LifePO4Mini 3.3V.
PurePi II is an improved version over PurePi with some new features.
PurePi II2026 is the Most up-to-date version that was released in early 2026.

Features and Specifications

• 5V ultracapacitor power supply with two 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

PurePi II 2026 New Features:

1. New optional 5V input pads on PCB – allows direct soldering of high-quality external 5V power supply wires if the USB-C power adapter is not preferred
2. Optimized PCB layout design for lower internal ESR
3. 120F/3.0V high performance ultracapacitors
4. Precision manufacturing
5. High current output terminal connectors can fit larger AWG wires or bi-wiring connections 
6. Highlighted silkscreen labels and markers
7. Output noise cleaning performance for 5V:
    Noise density is 25–30 dB lower than the input (10 Hz – 100 kHz)
8. Output noise (3.3V Pure Mode): As low as the battery noise level

Please carefully read through the users manual before you get started.

PurePi User's manual

Other Documents

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. The standard 3.7V Lithium battery doesn't work. 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.
   
2. There will be no 3.3V output if LifePO4 batteries are not installed.
   
3. 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 RPi versions. 
4. We highly recommend using high quality standard USB power adapters, for example 65W Anker or UGREEN for PurePi. Apple USB adapter may not work properly for non-Apple devices. And the RaspberryPi official 27W USB power adapter uses private PD protocol and it may only deliver enough current when connects to a RaspberryPi USB-C power input port. If PurePi quits the conditioning mode (D13 turns off), normally it because of the low quality USB power adapter and cable which can not keep higher than 4.9V voltage while deliver high current. A high quality USB power adapter and a shorter cable can solve this issue . Never use USB extension cables. It's also highly recommend to use a high quality USB-A to USB-C cable (higher 5V current than USB-C to USB-C cable) and connect to the UcPure first and then to the USB power adapter.
5. PurePi is not a UPS, it doesn't work if power input is disconnected.
6. How to connect a non-USB external 5V power supply to a PurePi II2026: Please solder the two output wires of a high quality external 5V power supply (Linear power supply with 3A or higher output current is proffered) directly to the two pads that marked + and - at back side of the PCB beside the USB connector. Please be very careful don't reverse the polarity or short circuit.

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. Non-conductive tools are highly recommended for installation.