[{"data":1,"prerenderedAt":378},["ShallowReactive",2],{"guide-en-jk-bms-calibration":3,"guides-en":246},{"id":4,"title":5,"body":6,"date":224,"description":225,"extension":226,"keywords":227,"meta":234,"navigation":235,"path":236,"related":237,"seo":242,"stem":243,"updated":244,"__hash__":245},"guides_en\u002Fguides\u002Fjk-bms-calibration.md","JK BMS Voltage and Current Calibration: How to Do It Right",{"type":7,"value":8,"toc":207},"minimark",[9,13,18,21,29,57,61,76,80,94,97,101,115,118,122,125,156,160,163,167,175,179,184,187,191,194,198,201],[10,11,12],"p",{},"JK BMS calibration corrects the pack voltage and the current the BMS measures. You measure the real value with a good meter, type it into Calibrating Voltage or Calibrating Current in the JK app, and press the set button next to it. Do it only when the readings are clearly wrong, use a steady reference, and calibrate current under a stable load. Most \"calibration fails\" stories come from entering a value the BMS cannot see at that moment.",[14,15,17],"h2",{"id":16},"what-calibration-does-and-what-it-does-not-do","What calibration does and what it does not do",[10,19,20],{},"The official manual describes both functions in one line each: when the total voltage collected by the BMS differs from the real total voltage, fill in the measured voltage and press set; when the measured current differs from the real current, fill in the real current and press set.",[10,22,23,24,28],{},"What calibration does ",[25,26,27],"strong",{},"not"," fix:",[30,31,32,45,51],"ul",{},[33,34,35,38,39,44],"li",{},[25,36,37],{},"A wrong state of charge."," SOC comes from counting current over time against the capacity setting. A wrong capacity or a missing full charge throws it off far more than a small current error. See ",[40,41,43],"a",{"href":42},"\u002Fguides\u002Fjk-bms-soc-calibration","SOC calibration"," first.",[33,46,47,50],{},[25,48,49],{},"Single cell readings."," Voltage calibration scales the pack voltage. A single cell that reads off is usually a balance lead or a contact problem.",[33,52,53,56],{},[25,54,55],{},"Inverter disagreement."," The inverter measures at its own terminals, after cables and fuses. A few tenths of a volt between them is normal.",[14,58,60],{"id":59},"before-you-calibrate","Before you calibrate",[62,63,64,67,70,73],"ol",{},[33,65,66],{},"Use a meter you trust. A cheap meter that is off by 0.5% makes things worse.",[33,68,69],{},"Measure at the BMS: pack voltage between B+ and B-, current with a clamp meter on the main cable or with a shunt.",[33,71,72],{},"Compare in a quiet state. For voltage, no load and no charging for a few minutes. For current, a steady load that does not jump.",[33,74,75],{},"Write down the BMS reading and your reading. If they differ by less than about 0.3% for voltage, leave it alone.",[14,77,79],{"id":78},"how-to-calibrate-the-voltage","How to calibrate the voltage",[62,81,82,85,88,91],{},[33,83,84],{},"Rest the battery for a few minutes.",[33,86,87],{},"Measure the pack voltage at B+ and B-.",[33,89,90],{},"In the JK app, enter that value in Calibrating Voltage and press the set button next to it.",[33,92,93],{},"Check that the pack voltage in the app now matches your meter.",[10,95,96],{},"Some inverter owners deliberately enter a slightly higher value so the inverter reaches its own full charge voltage. That moves every voltage based decision of the BMS too, so we prefer to change the inverter's charge voltage instead.",[14,98,100],{"id":99},"how-to-calibrate-the-current","How to calibrate the current",[62,102,103,106,109,112],{},[33,104,105],{},"Apply a steady, known current: a constant load or a charger in constant current mode. A load that pulses, like an inverter at low power, gives a useless reference.",[33,107,108],{},"Measure the current with a clamp meter or a shunt.",[33,110,111],{},"Enter the measured value in Calibrating Current and press set.",[33,113,114],{},"Check the reading at another current. If it is good at one point and off at another, the issue is not calibration.",[10,116,117],{},"Owners report that newer firmware also offers a zero current calibration, which helps when the BMS shows a small current with nothing connected.",[14,119,121],{"id":120},"why-calibration-ends-in-sending-failure","Why calibration ends in Sending failure",[10,123,124],{},"Forum reports point to a few causes:",[30,126,127,133,139,145],{},[33,128,129,132],{},[25,130,131],{},"The value is far from what the BMS measures."," Users found the BMS refused a reference higher than the current it saw at that moment. Calibrate when the BMS really sees the current you enter.",[33,134,135,138],{},[25,136,137],{},"No current is flowing."," Current calibration with no load has nothing to scale.",[33,140,141,144],{},[25,142,143],{},"Another fault is active."," In one case calibration failed while a cell count mismatch was active. Clear alarms first.",[33,146,147,150,151,155],{},[25,148,149],{},"The general cause."," The firmware checks each value when it arrives. Our ",[40,152,154],{"href":153},"\u002Fguides\u002Fjk-bms-sending-failure","Sending failure guide"," explains this for normal settings.",[14,157,159],{"id":158},"discharge-current-reads-high-with-an-inverter","Discharge current reads high with an inverter",[10,161,162],{},"With an inverter, the discharge current often looks higher on the BMS than on a shunt. Inverters draw current in pulses, and a BMS that samples quickly can read those peaks differently from a meter that averages. Do not try to calibrate this away at one load. Compare at several loads and accept a small difference, or use a separate shunt for energy accounting.",[14,164,166],{"id":165},"checking-the-result","Checking the result",[10,168,169,170,174],{},"Calibration is done in the JK app, because it is a command rather than a stored setting, so our editor does not send it. You can check the result in the browser: ",[40,171,173],{"href":172},"\u002F","connect your BMS"," and open the live monitor, which records pack voltage, current and power over time. Run a known load and compare the curve with your meter.",[14,176,178],{"id":177},"faq","FAQ",[180,181,183],"h3",{"id":182},"should-i-calibrate-a-new-jk-bms","Should I calibrate a new JK BMS?",[10,185,186],{},"Usually not. Calibrate only if your trusted meter shows a clear difference, well above 0.3% for voltage, or a current error that stays the same across loads.",[180,188,190],{"id":189},"why-does-my-jk-bms-show-current-with-nothing-connected","Why does my JK BMS show current with nothing connected?",[10,192,193],{},"A small offset of a few hundred milliamps is common. If your firmware has zero current calibration, run it with everything disconnected. Otherwise ignore an offset that small.",[180,195,197],{"id":196},"does-calibration-fix-a-wrong-soc","Does calibration fix a wrong SOC?",[10,199,200],{},"Rarely. SOC errors mostly come from a wrong capacity setting or missing full charges. Fix those first and calibrate current only if it is clearly off.",[10,202,203,206],{},[40,204,205],{"href":172},"Connect your BMS"," to compare its readings with your meter over time.",{"title":208,"searchDepth":209,"depth":209,"links":210},"",3,[211,213,214,215,216,217,218,219],{"id":16,"depth":212,"text":17},2,{"id":59,"depth":212,"text":60},{"id":78,"depth":212,"text":79},{"id":99,"depth":212,"text":100},{"id":120,"depth":212,"text":121},{"id":158,"depth":212,"text":159},{"id":165,"depth":212,"text":166},{"id":177,"depth":212,"text":178,"children":220},[221,222,223],{"id":182,"depth":209,"text":183},{"id":189,"depth":209,"text":190},{"id":196,"depth":209,"text":197},"2026-10-14","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.","md",[228,229,230,231,232,233],"jk bms calibration","jk bms current calibration","jk bms calibrating voltage","jk bms calibrating current","jk bms calibrating current sending failure","jk bms voltage calibration",{},true,"\u002Fguides\u002Fjk-bms-calibration",[238,239,240,241],"jk-bms-soc-calibration","jk-bms-sending-failure","jk-bms-first-setup","jk-bms-soc-stuck-at-99",{"title":5,"description":225},"guides\u002Fjk-bms-calibration",null,"Jz1g7Y7d_ulQ7swNbpcxU3ChVNDyiQxkbeeS74rRJzg",[247,251,255,256,260,264,268,272,276,280,284,288,293,297,301,305,309,314,319,324,328,332,336,340,344,348,352,356,360,364,367,370,374],{"path":248,"title":249,"description":250,"date":224,"updated":244},"\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":252,"title":253,"description":254,"date":224,"updated":244},"\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":236,"title":5,"description":225,"date":224,"updated":244},{"path":257,"title":258,"description":259,"date":224,"updated":244},"\u002Fguides\u002Fjk-bms-error-codes","JK BMS Error Codes: What the Display and LEDs Are Telling You","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.",{"path":261,"title":262,"description":263,"date":224,"updated":244},"\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":265,"title":266,"description":267,"date":224,"updated":244},"\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":269,"title":270,"description":271,"date":224,"updated":244},"\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":273,"title":274,"description":275,"date":224,"updated":244},"\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":277,"title":278,"description":279,"date":224,"updated":244},"\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":281,"title":282,"description":283,"date":224,"updated":244},"\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":285,"title":286,"description":287,"date":224,"updated":244},"\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":289,"title":290,"description":291,"date":292,"updated":244},"\u002Fguides\u002Fjk-bms-alarms-list","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":294,"title":295,"description":296,"date":292,"updated":244},"\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":298,"title":299,"description":300,"date":292,"updated":244},"\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":302,"title":303,"description":304,"date":292,"updated":244},"\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":306,"title":307,"description":308,"date":292,"updated":244},"\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. 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See factory defaults, how to change them, what to try if one fails, and what to do if lost.",{"path":361,"title":362,"description":363,"date":323,"updated":318},"\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":153,"title":365,"description":366,"date":323,"updated":318},"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":42,"title":368,"description":369,"date":323,"updated":313},"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":371,"title":372,"description":373,"date":323,"updated":244},"\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":375,"title":376,"description":377,"date":323,"updated":318},"\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.",1791980001822]