[{"data":1,"prerenderedAt":428},["ShallowReactive",2],{"guide-en-jk-bms-error-codes":3,"guides-en":297},{"id":4,"title":5,"body":6,"date":275,"description":276,"extension":277,"keywords":278,"meta":285,"navigation":286,"path":287,"related":288,"seo":293,"stem":294,"updated":295,"__hash__":296},"guides_en\u002Fguides\u002Fjk-bms-error-codes.md","JK BMS Error Codes: What the Display and LEDs Are Telling You",{"type":7,"value":8,"toc":259},"minimark",[9,13,18,21,50,54,57,129,138,142,145,165,168,172,213,217,220,224,229,232,236,239,243,246,250,253],[10,11,12],"p",{},"JK does not publish an official list of numbered JK BMS error codes. The numbers you see on a small display, such as Err 4, Err 7 or error 9, are shorthand for the same alarms the app shows by name: cell over voltage, cell count mismatch, over current, temperature and so on. The reliable way to decode one is to read the alarm name in the app or in a browser over Bluetooth, then fix that alarm. This guide shows what is documented, what users have matched so far, and how to find the cause fast.",[14,15,17],"h2",{"id":16},"where-jk-bms-error-codes-appear","Where JK BMS error codes appear",[10,19,20],{},"There are four places a JK battery can report a fault, and they are easy to mix up:",[22,23,24,32,38,44],"ul",{},[25,26,27,31],"li",{},[28,29,30],"strong",{},"The small display"," on B2A and similar boards shows short codes and often beeps.",[25,33,34,37],{},[28,35,36],{},"The LEDs"," on PB inverter boards: ON\u002FOFF, RUN, ALM and six SOC lights.",[25,39,40,43],{},[28,41,42],{},"The app or a Bluetooth reader"," shows the full alarm names.",[25,45,46,49],{},[28,47,48],{},"The inverter screen"," shows the inverter's own fault numbers, for example when it loses communication with the BMS. Those are not BMS codes, so look them up in the inverter manual.",[14,51,53],{"id":52},"what-the-official-documents-say","What the official documents say",[10,55,56],{},"The PB2A16S20P specification is the most detailed official source. It describes the LEDs, not numbers:",[58,59,60,79],"table",{},[61,62,63],"thead",{},[64,65,66,70,73,76],"tr",{},[67,68,69],"th",{},"Situation",[67,71,72],{},"ON\u002FOFF",[67,74,75],{},"RUN",[67,77,78],{},"ALM",[80,81,82,96,108,119],"tbody",{},[64,83,84,88,91,93],{},[85,86,87],"td",{},"Normal charging, discharging or balancing",[85,89,90],{},"On",[85,92,90],{},[85,94,95],{},"Off",[64,97,98,101,103,105],{},[85,99,100],{},"Over current, over temperature, over or under voltage, charge or discharge fail",[85,102,90],{},[85,104,90],{},[85,106,107],{},"Blinking",[64,109,110,113,115,117],{},[85,111,112],{},"Other warnings: password not changed, short circuit, abnormal temperature",[85,114,90],{},[85,116,90],{},[85,118,107],{},[64,120,121,123,125,127],{},[85,122,95],{},[85,124,95],{},[85,126,95],{},[85,128,95],{},[10,130,131,132,137],{},"The PB manual adds that ALM is for system faults. Note the line about the password: a blinking ALM on a brand new battery can simply mean the default password was never changed. The ",[133,134,136],"a",{"href":135},"\u002Fguides\u002Fjk-bms-password","password guide"," explains how to change it.",[14,139,141],{"id":140},"codes-users-have-matched-to-real-faults","Codes users have matched to real faults",[10,143,144],{},"These are reports from owners, not JK statements, so treat them as a starting point:",[22,146,147,153,159],{},[25,148,149,152],{},[28,150,151],{},"Err 7, often together with Err 4 and constant beeping."," Seen on 4S and 8S boards when the app reported that the cell count does not match the settings. The fixes were a loose or swapped balance lead, a damaged sense wire, or a wrong cell count in the settings.",[25,154,155,158],{},[28,156,157],{},"Error code 3 on a PB2A16S20P."," One owner matched it to a charge over current event: the charger pushed more current than the max charge current setting.",[25,160,161,164],{},[28,162,163],{},"Error 9."," We found no confirmed meaning. If you see it, read the alarm name over Bluetooth and add it to your notes; that is the only way to be sure.",[10,166,167],{},"Because the codes are not documented, the same number may mean something else on another model or firmware. Always confirm with the alarm name.",[14,169,171],{"id":170},"how-to-find-the-cause-in-three-steps","How to find the cause in three steps",[173,174,175,191,197],"ol",{},[25,176,177,180,181,185,186,190],{},[28,178,179],{},"Read the alarm name."," Connect with the JK app, or ",[133,182,184],{"href":183},"\u002F","connect in the browser"," and open the live monitor. Active alarms are listed by name with the settings that control them. The ",[133,187,189],{"href":188},"\u002Fguides\u002Fjk-bms-alarms-list","alarms list"," explains each one.",[25,192,193,196],{},[28,194,195],{},"Check the cell count first."," A cell count mismatch is the most common reason for codes plus beeping on a new build. Compare the cell count setting with your pack and measure each balance pin against B-.",[25,198,199,202,203,207,208,212],{},[28,200,201],{},"Look at the history."," Export the Detail Log from the JK app and drop it into the ",[133,204,206],{"href":205},"\u002Flogs","log analysis",". It pairs every trip with its release, so you see whether the fault repeats and what triggered it. The ",[133,209,211],{"href":210},"\u002Fguides\u002Fjk-bms-log-messages-explained","log messages guide"," covers the wording.",[14,214,216],{"id":215},"silencing-the-beeping","Silencing the beeping",[10,218,219],{},"The beeping stops when the alarm clears. Holding the power button for about 3 seconds can quiet it on some boards, but the alarm comes back if the cause remains, and on PB boards the same press turns the BMS off. Fix the cause instead: wrong cell count, a balance lead, a cell above OVP or below UVP.",[14,221,223],{"id":222},"faq","FAQ",[225,226,228],"h3",{"id":227},"what-does-jk-bms-error-7-mean","What does JK BMS error 7 mean?",[10,230,231],{},"Owners report Err 7 together with a cell count mismatch, usually caused by a loose, swapped or broken balance lead, or by a cell count setting that does not match the pack. Check the wiring and the setting first.",[225,233,235],{"id":234},"what-does-jk-bms-error-9-mean","What does JK BMS error 9 mean?",[10,237,238],{},"There is no confirmed public meaning for error 9. Read the alarm name in the app or over Bluetooth while the code is shown; the name tells you which protection is active and which setting controls it.",[225,240,242],{"id":241},"why-is-the-alm-light-blinking-on-my-jk-inverter-bms","Why is the ALM light blinking on my JK inverter BMS?",[10,244,245],{},"The ALM light blinks for faults such as over current, over temperature or over voltage, and also when the default password has not been changed. Read the active alarm over Bluetooth to tell them apart.",[225,247,249],{"id":248},"how-do-i-reset-a-jk-bms-error","How do I reset a JK BMS error?",[10,251,252],{},"Most alarms clear on their own once the cause is gone, for example when a cell drops back below the recovery voltage. Over current alarms clear after the recovery time. Restarting without fixing the cause brings the code back.",[10,254,255,258],{},[133,256,257],{"href":183},"Connect your BMS"," to see active alarms by name, with links to the settings behind them.",{"title":260,"searchDepth":261,"depth":261,"links":262},"",3,[263,265,266,267,268,269],{"id":16,"depth":264,"text":17},2,{"id":52,"depth":264,"text":53},{"id":140,"depth":264,"text":141},{"id":170,"depth":264,"text":171},{"id":215,"depth":264,"text":216},{"id":222,"depth":264,"text":223,"children":270},[271,272,273,274],{"id":227,"depth":261,"text":228},{"id":234,"depth":261,"text":235},{"id":241,"depth":261,"text":242},{"id":248,"depth":261,"text":249},"2026-10-14","JK BMS error codes explained: what the Err numbers, the ALM light and the app alarms mean, which codes users have matched to real faults, and how to find the cause.","md",[279,280,281,282,283,284],"jk bms error codes","jk bms error codes list","jk bms error 7","jk bms error 9","jk bms alm light","jk bms beeping",{},true,"\u002Fguides\u002Fjk-bms-error-codes",[289,290,291,292],"jk-bms-alarms-list","jk-bms-log-messages-explained","jk-bms-not-turning-on","jk-bms-detail-log",{"title":5,"description":276},"guides\u002Fjk-bms-error-codes",null,"w6OC_pH_Xy_gLuApQEUSyrX1H53Q9DlV0SLzmiqlYZE",[298,302,306,310,311,315,319,323,327,331,335,339,343,347,351,355,359,364,369,374,378,382,386,390,393,397,401,405,408,412,416,420,424],{"path":299,"title":300,"description":301,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-app-alternative","JK BMS App Alternative: Change Settings from Your PC or Browser","Looking for a JK BMS app alternative? Compare the JK app, the PC monitor software, ESPHome and a browser editor that reads and writes settings over Bluetooth.",{"path":303,"title":304,"description":305,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-bluetooth-not-connecting","JK BMS Not Connecting over Bluetooth: Fixes That Work","JK BMS not connecting or not pairing over Bluetooth? Work through the causes in order: sleep, another app holding the link, permissions, range and the browser.",{"path":307,"title":308,"description":309,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-calibration","JK BMS Voltage and Current Calibration: How to Do It Right","How to calibrate JK BMS voltage and current: what to measure, which value to enter, why calibration ends in Sending failure, and when to leave it alone.",{"path":287,"title":5,"description":276,"date":275,"updated":295},{"path":312,"title":313,"description":314,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-firmware","JK BMS Firmware: V15 vs V19 and How to Update Safely","JK BMS firmware explained: how to read your hardware and software version, what changed from V11 to V15 and V19, and how to update without bricking the BMS.",{"path":316,"title":317,"description":318,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-first-setup","How to Set Up a New JK BMS: First Start Step by Step","Set up a new JK BMS the right way: wiring order, first power-on, passwords, cell count, a chemistry preset, current limits and a verified write over Bluetooth.",{"path":320,"title":321,"description":322,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-not-charging","JK BMS Not Charging or Discharging: Why the MOSFET Is Off","JK BMS not charging or not discharging? Find which protection or switch turned the MOSFET off, how to tell the causes apart and which setting fixes each one.",{"path":324,"title":325,"description":326,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-not-turning-on","JK BMS Not Turning On: How to Start and Wake It Up","JK BMS not turning on? Learn how to activate a new board with a charger or the button, wake it from sleep, and find the wiring faults that keep it dark.",{"path":328,"title":329,"description":330,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-precharge","JK BMS Precharge: Stop Sparks and SCP Trips on Inverter Start","What JK BMS precharge does, why inverter capacitors trip short circuit protection, how to set the precharge time and when you still need a precharge resistor.",{"path":332,"title":333,"description":334,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-reset","How to Reset a JK BMS: SOC, Capacity, Alarms and Settings","How to reset a JK BMS: reset the SOC, the capacity, a stuck alarm or all settings, what the cycle count really is, and why you should back up before any reset.",{"path":336,"title":337,"description":338,"date":275,"updated":295},"\u002Fguides\u002Fjk-bms-smart-sleep","JK BMS Smart Sleep: What the Voltage and Time Settings Do","What JK BMS smart sleep does, how the smart sleep voltage and time work together, how to wake a sleeping BMS and which values to use for home storage or a camper.",{"path":188,"title":340,"description":341,"date":342,"updated":295},"JK BMS Alarms List: Every Alarm, Its Cause and the Fix","All JK BMS alarms in one table: what each one means, what usually triggers it and which setting governs it, from cell OVP and MOS OTP to wire resistance.","2026-10-12",{"path":344,"title":345,"description":346,"date":342,"updated":295},"\u002Fguides\u002Fjk-bms-inverter-communication","JK Inverter BMS Communication: Deye, Victron and Growatt Setup","Connect a JK inverter BMS to Deye, Victron or Growatt over CAN or RS485: protocol number, port mode, DIP address, cable pinout and the inverter-side settings.",{"path":348,"title":349,"description":350,"date":342,"updated":295},"\u002Fguides\u002Fjk-bms-model-number-explained","JK BMS Model Numbers Explained: B2A8S20P, PB2A16S20P and More","Decode any JK BMS model name: series, balance current, cell count and current rating, plus the -H, -HC and -R suffixes and what they mean for heating, CAN and RS485.",{"path":352,"title":353,"description":354,"date":342,"updated":295},"\u002Fguides\u002Fjk-bms-parallel-batteries","JK BMS Parallel Batteries: Wiring, DIP Addresses and Settings","Connect several JK inverter BMS packs in parallel: busbar wiring, the RS485-2 link, DIP switch addresses, the master pack, matching settings and current limits.",{"path":356,"title":357,"description":358,"date":342,"updated":295},"\u002Fguides\u002Fjk-bms-temperature-heating-settings","JK BMS Temperature and Heating Settings: Safe Values for LiFePO4","Set JK BMS charge and discharge temperature limits, MOS OTP and the heating function. Why the -20 °C factory default is wrong for LiFePO4 and what to use instead.",{"path":360,"title":361,"description":362,"date":363,"updated":295},"\u002Fguides\u002Fjk-bms-soc-stuck-at-99","JK BMS SOC Stuck at 99%: Why It Never Reaches 100% and the Fix","JK BMS SOC stuck at 99% and never showing 100%? See what the BMS waits for at the end of charging, the six usual causes, and the settings that fix it.","2026-10-07",{"path":365,"title":366,"description":367,"date":368,"updated":295},"\u002Fguides\u002Fjk-bms-bluetooth-browser","Change JK BMS Settings over Bluetooth in Your Browser","Connect to a JK BMS from Chrome or Edge, read every setting, apply a preset and write it back in a safe order with read-back checks. No JK app needed.","2026-10-04",{"path":370,"title":371,"description":372,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-balance-settings","JK BMS Balance Settings: Start Voltage, Trigger, Current","JK BMS balance settings explained: start balance voltage, balance trigger voltage, max balance current and the Balancer switch, for LFP, NMC and LTO.","2026-10-02",{"path":375,"title":376,"description":377,"date":373,"updated":295},"\u002Fguides\u002Fjk-bms-cell-overcharge-protection-tripping","JK BMS Cell Over Charge Protection Keeps Tripping: Causes and Fix","JK BMS cell over charge protection tripping and releasing every minute? See why a charger set too high causes it, how to tell it from a weak cell, and how to fix it.",{"path":379,"title":380,"description":381,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-detail-log","How to export and read the JK-BMS Detail Log","What the JK-BMS Detail Log contains, how to export it from the app, how to read its events and what the log analysis page tells you about trips and faults.",{"path":383,"title":384,"description":385,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-export-import-settings","Export and Import JK BMS Settings: The .jkcfg File Guide","How to export and import JK BMS settings with the app, what the .jkcfg file contains, why hand edits break it, and how to edit it safely in your browser.",{"path":387,"title":388,"description":389,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-lifepo4-settings","JK BMS Settings for LiFePO4: 8S and 16S, 280Ah and 314Ah","JK BMS settings for LiFePO4 packs: per-cell voltage, balance, current and temperature values for 8S and 16S with 280Ah and 314Ah cells, in three wear levels.",{"path":210,"title":391,"description":392,"date":373,"updated":295},"JK BMS Log Messages Explained: Boot, Time calibration, Protections","What each JK BMS log message means: Boot, Time calibration, APP open charge, protection trips and releases, Discharge On Failed and Unknown Log Code [0].",{"path":394,"title":395,"description":396,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-nmc-lto-settings","JK BMS Settings for NMC and LTO: Safe Per-Cell Values","JK BMS settings for NMC and LTO packs: per-cell OVP, UVP, balance, temperature and C-rate values in three wear levels, plus how the editor detects chemistry.",{"path":398,"title":399,"description":400,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-ocp-scp-settings","JK BMS Overcurrent Protection Settings: OCP and SCP Guide","JK BMS overcurrent protection settings explained: charge and discharge OCP limits, delays, recovery times and SCP, with ranges and sizing for inverters.",{"path":402,"title":403,"description":404,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-parameters-explained","JK BMS Parameters Explained: Every Setting by Group","JK BMS parameters explained in one glossary: cell OVP, OVPR, UVP, UVPR, balance, SOC, RCV and RFV, current and temperature limits, with typical LFP ranges.",{"path":135,"title":406,"description":407,"date":373,"updated":368},"JK BMS Password: Default Codes, Change and Reset Guide","Your JK BMS password is really two codes: Bluetooth and settings. See factory defaults, how to change them, what to try if one fails, and what to do if lost.",{"path":409,"title":410,"description":411,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-reboots-power-events","JK BMS Reboots and Charge MOS Off: Reading Power Events in the Log","JK BMS reboots or the charge MOS switched off by itself? Learn to read Boot rows and MOS state in the Detail Log and tell expected restarts from real faults.",{"path":413,"title":414,"description":415,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-sending-failure","JK BMS Sending failure: Causes and Step-by-Step Fix","JK BMS Sending failure on import? See why the firmware rejects settings (voltage chains, write order, SCP delay) and how to fix it step by step.",{"path":417,"title":418,"description":419,"date":373,"updated":363},"\u002Fguides\u002Fjk-bms-soc-calibration","JK BMS SOC Calibration: Fix SOC Drift, Jumps and Reset","JK BMS SOC calibration explained: why SOC drifts or jumps, what the SOC-100% voltage and SOC-0% voltage do, and how to set them and recalibrate the pack.",{"path":421,"title":422,"description":423,"date":373,"updated":295},"\u002Fguides\u002Fjk-bms-weak-cell-log","Find a Weak Cell with the JK BMS Log: Trips, Spread and Balance","Find a weak cell in the JK BMS Detail Log: which cell trips first, how wide the spread is at the trip, and whether it is balance drift or a bad cell.",{"path":425,"title":426,"description":427,"date":373,"updated":368},"\u002Fguides\u002Fjk-bms-wire-resistance","JK BMS Wire Resistance: Fix Abnormal Balance Wire Alarm","JK BMS wire resistance explained: what the abnormal resistance of the balance wire warning means, normal values, common causes and how to fix a bad lead.",1791980001963]