If you're entrusting 292 Wh and 330 W to a power bank, you have the right to know what's inside. All of FRAGWATT's critical tasks were handed over to chips with publicly available datasheets that run in millions of battery packs, vehicles, and laptops around the world. We didn't invent our own protection circuit; We used the most tested ones in the right place, in independent layers.
chips inside
Which chip performs which task on each card, why it was chosen and the manufacturer's own page. All links in circuit diagrams can be viewed individually.
21700 cell of 4.5 Ah designed for high current; The manufacturer specifies 45 A continuous discharge. Even at the heaviest load the current per cell on the FRAGWATT is ~16 A on the Solo, ~5 A on the Trio: well below the limit, so the cells stay cool and long-lasting.
Tracer and protector for packs of 3–10 serial cells. Measures each cell's voltage, current, and temperatures with its own two independent ADCs; It cuts off FETs in case of overvoltage, overcurrent and short circuit without waiting for the software.
An independent secondary monitor, separate from the main AFE. It checks each cell for overvoltage, undervoltage and a disconnected lead. If a cell exceeds 4.35 V, it trips a 3-terminal fuse to isolate the pack permanently.
60V, 4-switch, bi-directional buck-boost controller. Two of them work intermittently (two phases) and deliver 330 W to the laptop with 98.4% efficiency; The same floor works in the opposite direction and receives 330 W charging from the laptop adapter.
70 V standalone or I²C controlled bi-directional buck-boost charge controller. Converts 5–48 V from USB-C to cells; delivers 140W from USB-C1 in reverse direction.
USB Power Delivery 3.1 controller certified by USB-IF. Contracts 28, 36 or 48 V EPR with the charger and supports AVS; The contract is handled by a chip that has gone through the USB standard's own testing processes.
The most common malfunction of USB-C at 48 V EPR is VBUS touching the CC or SBU pin on a bent plug. This protector protects CC and SBU lines against short circuit and ESD up to 63 V; Part of TI's 240 W reference design.
9–80 V hotplug controller, electronic fuse of output to laptop on FRAGWATT. Programmably limits the current limit and the power consumed by the FET; It cuts the FET in case of a short circuit, keeping it in the safe operating area.
An Arm Cortex-M0+ microcontroller commonly used in industry. It runs FRAGWATT's BMS software, connector tip detection, power profiles and display; an independent watchdog detects lockups.
Kararti Radio that connects with the Link app. It is used as a module with radio approvals; Supports secure boot and flash encryption, only signed updates will work.
Security
The layers work independently of each other.
Breaks short circuit in ~100 µs (SPICE: 213 A, 103 µs). Over/under voltage, current and temperature protections are independent of the software.
Reduces power from 45 °C, cuts off at 60 °C; balances cells; It does not open an exit until the end is recognized. It passes 82 automated tests.
If the cell exceeds 4.35 V, a separate protection IC blows the 3-prong fuse. E-fuse and 22 V surge lock at the output protect the laptop.
Target certifications: UN 38.3, IEC 62133-2, IEC 62368-1, CE (LVD, EMC, RED), RoHS. It will be completed before mass production.
evidence
We don't get confidence from the parts list alone. Every layer of the design has been tested and the results are clear on this site.
BMS software runs with actual code, depending on battery and heat pattern: short circuit, overheat, lead replacement, hot insertion. It all works again with every change.
The short-circuit break time was measured in SPICE (213 A peak, 103 µs). Proteus simulation circuit and HEX file are on the engineering page.
7-page circuit diagram, 344-component catalogue, PCB layers and mechanical assembly: on the engineering page downloadable.
Target certifications: UN 38.3, IEC 62133-2, IEC 62368-1, CE (LVD, EMC, RED), RoHS. It will be completed before mass production; USB-IF certification belongs to PD controller chip, product certification will be done separately.