BatMon: BMS Battery Monitor

BatMon is a read-only monitor for lithium batteries with a JK, JBD (Xiaoxiang) or Daly Bluetooth BMS. It was built to fix what people complain about most in BMS apps: links that drop, forced accounts, confusing numbers and lost passwords.

A CONNECTION THAT KEEPS ITSELF ALIVE
• Reconnects by itself with growing pauses instead of hammering the BMS
• Searches for the battery first after Android Bluetooth errors (the infamous "error 133")
• Notices when data stops, asks again, and rebuilds the link if needed
• A Connection health panel shows drops, recoveries and corrupted frames
• A Keep it running checklist covers battery saver, notifications and, on Xiaomi, Huawei, OPPO and vivo phones, autostart

EVERY BATTERY ON ONE SCREEN
• Combined bank view: total state of charge, power and time to full or empty
• One card per battery, with live current, power and cell gap
• Tap an alert to jump straight to the cells or history behind it

NUMBERS YOU CAN UNDERSTAND
• Tap any value for a plain-English explanation
• Cell chart that highlights the highest and lowest cell
• BMS alarms translated into what happened and what to do

ALERTS
• Cells drifting apart, low battery, high temperature, charging below freezing and every BMS alarm
• Notifications only after two readings in a row, so one noisy frame never wakes you up
• Tap a notification to open the battery that raised it

HISTORY
• Charge curve, cell gap and power over time, saved on your phone
• 24 hours free, up to 90 days with Pro, plus CSV export

LOCATION TRACK (Pro)
• For vans, boats and e-vehicles: see on a map where each battery has been
• Distance, energy used per kilometre and the last place it was seen
• Record every 30 seconds up to every 15 minutes, and export GPX
• Off by default, and positions never leave your phone

REMOTE MONITORING
• Leave a spare phone next to the batteries and turn on Share this phone
• Scan its QR code on your main phone to watch the cabin, boat or RV from anywhere
• Sharing is free while BatMon stays open on the spare phone; Pro or Remote keeps it going in the background
• Watching needs the Remote subscription (2 sites) or Pro (any number of sites)

PRIVATE BY DESIGN
• No account, no sign-in, no ads, no analytics
• Works without internet. Battery data never leaves your phone unless you turn on Remote monitoring
• Bluetooth needs no location permission on Android 12 and newer. Location is used only if you turn on Location track
• Read-only: BatMon never writes settings to your BMS, so it can never lock you out with a password

FREE
• Live monitoring, explanations and alerts for two batteries
• 24 hours of history
• Demo batteries to try every screen without hardware

BATMON PRO (one-time purchase, unlocks every feature)
• Unlimited batteries in the bank view
• Remote monitoring of any number of sites
• Location track with map, distance, energy per km and GPX export
• History up to 90 days and CSV export
• Your own alert thresholds
• Monitoring and sharing in the background with the screen off

REMOTE MONITORING SUBSCRIPTION (monthly, 7-day free trial for new subscribers)
• Watch 2 remote sites, with alerts on your main phone while you are away
• More than 2 batteries in the home bank
• Also unlocks Location track, 90-day history, custom alerts and background monitoring
• Cancel any time in Google Play; cancel during the trial and you are not charged

COMPATIBILITY
• JK BMS with the JK02 Bluetooth protocol (hardware version 10 and newer, for example JK-B2A24S and JK-PB series)
• JBD / Xiaoxiang smart BMS, including many batteries sold under other brands
• Daly smart BMS with a Bluetooth module (DL-…)
Mix brands freely: every battery appears in the same bank view.

BatMon is an independent app and is not affiliated with or endorsed by Jikong, Jiabaida or Daly. Protocol decoding is based on the open-source esphome-jk-bms and aiobmsble projects (Apache License 2.0).