Bluetooth reaches about as far as you can throw a phone. These two devices sit with the batteries and carry the readings the rest of the way — so the boat in storage, the RV in the driveway and the cabin off-grid all show up in the same app you already use.
A small ESP32 board you tuck in near the packs and forget about. It holds the Bluetooth connections, reads every battery on a schedule, and pushes the numbers up so your phone can pull them from anywhere. Cheap enough to leave on the boat.
| Power | 12V straight from the boat/RV, or any USB brick |
| Install | Power only. Nothing wired to the batteries. |
| Radio | Bluetooth LE to the packs · Wi-Fi out |
| Batteries | Discovers them itself — all brands the app supports |
| Updates | Over the air. New BMS families arrive without a cable. |
The same brain in a body with a screen. Mount it at the helm or the RV panel and the whole bank is right there — charge rings, watts in and out, hours left — while it keeps relaying to the cloud in the background.
| Screen | 4.3" 800×480, capacitive touch |
| Power | Wide-range 7–36V input — 12V wires straight in |
| Install | Two wires: positive and negative. That's it. |
| Does | On-screen dashboard and cloud relay, at once |
| Enclosure | Cased board, panel or bracket mount |
No second app, no broker credentials, no MAC addresses, no web page to log into.
Give it power. 12V wire or a USB brick. The LED comes on.
Open Live BMS → Settings → Add a Link. The app finds it over Bluetooth. Tap it.
Type your Wi-Fi password once. Your network is already filled in. The app hands the credentials to the Link over Bluetooth.
It finds your batteries. They're listed with live voltage and charge while you name each one. Done.
Both devices exist and run today — the Link is a working prototype on my own boat, with custom firmware, multi-brand battery discovery and over-the-air updates. What's left before anyone else can buy one is the unglamorous part: enclosures, per-device accounts, a setup flow that survives strangers' Wi-Fi, and enough field hours to trust it unattended.
There's no price and no ship date yet, and I'd rather say that than invent one. If you're running a setup you'd want this for, tell me about it — the details of what people are actually powering are what decide what gets built next.
Live BMS