Bluetooth Battery Monitor App (iOS + Android)

Element 3 designs and sells LiFePO4 lithium batteries for the caravan, RV, and 4WD market. Our batteries use a JK BMS (model JK-B2A8S30P) that broadcasts live data over Bluetooth Low Energy (BLE). We want a clean, branded mobile app — "Element 3" — that connects to our batteries over Bluetooth and displays their live status, so our customers can monitor their battery from their phone. We're looking for an experienced mobile developer to build version 1 and publish it to the Apple App Store and Google Play. THE BIG ADVANTAGE FOR YOU The hard part is already done. We have a documented, working Bluetooth protocol implementation (a Python proof-of-concept) that already connects to the BMS and reads every value the app needs. We'll hand this to the selected developer. You are NOT reverse-engineering anything — you're building a polished app around a known, working data source. This is a build job, not an R&D job. WHAT THE APP NEEDS TO DO (v1 SCOPE) Connect to a single Element 3 battery over Bluetooth LE and display the following, updating live: Voltage (pack) Current (amps) — both charging and discharging Power (watts) State of charge (%) Battery cycle count Accumulated amp-hours MOSFET temperature and cell temperatures Balancing current Individual cell voltages (our packs have either 4 or 8 cells) Plus: A scan/connect screen to find and connect to the battery The app fully branded to Element 3 (we provide logo, colours, brand guidelines) All data stays on the device — no user accounts, no cloud, no server. This keeps v1 simple and privacy-clean. TECH REQUIREMENTS Cross-platform (Flutter strongly preferred; React Native considered) so we ship iOS and Android from one codebase. Demonstrable Bluetooth Low Energy experience is ESSENTIAL — including handling connection drops and automatic reconnection, and iOS Bluetooth permission and background behaviour. This is the part inexperienced developers underestimate. Built with current tooling (latest Xcode / iOS SDK) to meet current App Store requirements. DELIVERABLES Working iOS and Android apps, published to the Apple App Store and Google Play. Apps published under Element 3's own developer accounts — we own the accounts, you publish into them (we'll add you as a team member). Complete source code delivered in a Git repository owned by Element 3. Brand-consistent UI matching our provided assets. Brief setup/build documentation. PLEASE INCLUDE IN YOUR PROPOSAL Links to apps you've published that use Bluetooth LE (App Store / Google Play links — this matters; generic app experience is not enough). A short note on how you've handled BLE connection reliability (reconnection, background, permissions).