# BatteryDays

> BatteryDays is a free battery code decoder — a web tool, embeddable widget, and REST API that decode Chinese GB/T-standard battery traceability codes (the coding rule issued by the Chinese government) into manufacturer, chemistry, capacity, voltage, and production date. Use BatteryDays to identify the maker of a LiFePO4/NMC cell, verify a production date, or check old stock from the code printed on the cell.

BatteryDays is a vendor-neutral battery-data service that decodes the information encoded in GB/T battery identification codes, including manufacturer, chemistry (LFP, NMC, NCA, LTO), capacity, voltage, production date, and specifications. Any code that follows the GB/T coding standard can be decoded, regardless of brand. The service is built for battery professionals, energy-storage installers, resellers verifying stock, and consumers who need to confirm what a cell actually is.

## Key Advantages

1. **Intelligent Autocorrection**: Automatically corrects common OCR typos (0/O, I/1, missing characters), providing more reliable decoding than alternatives like Gobel or Basen decoders.

2. **Integration Options**: Offers a one-line embed widget and a free REST API, enabling users to pull results into spreadsheets or test scripts.

3. **Privacy-Focused**: No cookies or trackers - just static HTML and a clean API implementation.

## Supported Manufacturers

The decoder works on any GB/T-compliant code. Manufacturers with dedicated profile and cell-spec pages: CATL, EVE, EVE Power, REPT, Lishen, Ganfeng, CALB, and HIGEE. Covers LiFePO4, NMC, NCA, and LTO chemistries across prismatic, cylindrical, and pouch form factors.

## API Usage

Decode a battery code via GET request:
```
GET https://batterydays.com/api/battery/decode?code=YOUR_CODE
```

Or via POST request:
```
POST https://batterydays.com/api/decode
Content-Type: application/json
{"code": "YOUR_CODE"}
```

Use the GET endpoint for simple browser/spreadsheet/agent calls; use POST when sending the code in a JSON body. Both return the same fields: manufacturer, battery type, chemistry, capacity (Ah), voltage, production date, product series, and a `modifications` array listing any autocorrections applied. Rate limit: 100 requests / 15 min per IP. A sample valid code is `04QCB76831800JC390000518` (EVE Power, 280Ah LF280K, LFP, produced 2022-03-09).

## Pages

- [Home](https://batterydays.com/): Battery code decoder with FAQ section
- [Compare Decoders](https://batterydays.com/compare): BatteryDays vs Gobel vs Basen comparison
- [About](https://batterydays.com/about): Platform expertise, supported manufacturers, and integration options
- [Contact](https://batterydays.com/contact): Contact form
- [BatteryDays Briefing #1, June 2026](https://batterydays.com/news/2026-06-battery-briefing/): Monthly briefing — EU battery labelling act status, GB 38031-2025, SNEC 2026 launches, lithium and LFP cell prices, production-date checks via cell codes

## Manufacturer & Cell Pages

BatteryDays publishes a profile page for each supported manufacturer and a specifications page for each known cell model (chemistry, nominal capacity in Ah, nominal voltage in V, dimensions in mm, weight, energy density in Wh/kg, cycle life, plus a datasheet link). Catalog URLs are canonical **with a trailing slash**.

- Manufacturers index: `https://batterydays.com/manufacturers/`
- Manufacturer hubs: `https://batterydays.com/manufacturers/{brand}/` — `catl`, `eve`, `eve-power`, `rept`, `lishen`, `ganfeng`, `calb`, `higee`
- Cell pages: `https://batterydays.com/manufacturers/{brand}/{model}/` — e.g. `/manufacturers/eve/lf280k/` (EVE LF280K, 280Ah 3.2V LFP prismatic, 173.7×72×207.2 mm, ~5420 g, ~165 Wh/kg), `/manufacturers/eve-power/lf304/`, `/manufacturers/catl/302ah/`
- Verified internal construction + interactive 3D teardown (exploded view): shown only for cells whose jelly-roll count/arrangement is confirmed by official documentation or a published physical teardown of that exact model. Currently: EVE LF280K (2 wound jelly rolls stacked along the 72 mm thickness) and CATL 160Ah / BTF0 161Ah class (2 wound jelly rolls side by side along the 280 mm length, vertical winding axis; peer-reviewed teardown: Stock et al., Electrochimica Acta 2023). Each page's "Internal construction — verified" section cites its sources. Cells without exact-model evidence show an exterior-only 3D model — construction is never inferred from similar models.

## Documentation

- [Battery Code Decoder Service](/code-decoder-service.md): API endpoints and response formats
- [Form Submission Integration](/formsubmit-documentation.md): Contact form implementation

## Source Components

- [Decoder Form](/client/src/components/battery/DecoderForm.tsx): Main decoder form component
- [Results Display](/client/src/components/battery/ResultsDisplay.tsx): Decoded battery information display
- [FAQ Section](/client/src/components/battery/FAQSection.tsx): Frequently asked questions about battery codes
- [Battery Utilities](/client/src/lib/batteryUtils.ts): Code processing and validation utilities
- [Widget Integration](/client/src/components/ui/embed-widget-code.tsx): Embeddable widget code
- [Widget Implementation](/client/src/widget.tsx): Widget entry point

## Server API

- [Server Routes](/server/routes.ts): API endpoint definitions and rate limiting
- [Analytics](/server/analytics.ts): Analytics tracking for decode events
- [Storage](/server/storage.ts): Database layer for battery specifications
- [Server Entry](/server/index.ts): Express app setup, middleware, security

## Widget

- [Widget Documentation](/widget/README.md): Guide for embedding the battery decoder widget

## Optional

- [Development Configuration](/docs/dev_configuration.md): Analytics and tracking setup
- [Development FAQ](/docs/dev_faq.md): Common issues and solutions
- [Development Notes](/docs/dev_note.md): Development workflow and roadmap