[{"data":1,"prerenderedAt":358},["ShallowReactive",2],{"guide-en-jk-bms-not-turning-on":3,"guides-en":227},{"id":4,"title":5,"body":6,"date":205,"description":206,"extension":207,"keywords":208,"meta":215,"navigation":216,"path":217,"related":218,"seo":223,"stem":224,"updated":225,"__hash__":226},"guides_en\u002Fguides\u002Fjk-bms-not-turning-on.md","JK BMS Not Turning On: How to Start and Wake It Up",{"type":7,"value":8,"toc":189},"minimark",[9,13,18,21,44,47,51,54,69,72,76,79,115,123,127,130,141,145,148,152,157,160,164,167,171,174,178,181],[10,11,12],"p",{},"A JK BMS that does not turn on is almost always waiting for an activation signal, asleep after a low voltage shutdown, or missing a wire. Standard boards like the B2A and BD6A series have no power switch: they start when a charger with a voltage at least 5 V above the pack voltage is connected. Inverter boards like the PB series start with a short press of the power button. If neither works, check the wiring order before you suspect a dead board.",[14,15,17],"h2",{"id":16},"how-a-jk-bms-is-meant-to-start","How a JK BMS is meant to start",[10,19,20],{},"JK documents two ways to bring a board to life, depending on the model:",[22,23,24,32,38],"ul",{},[25,26,27,31],"li",{},[28,29,30],"strong",{},"Charger activation (B2A, BD6A, B1A and similar)."," The official manual says the BMS \"does not have a power-on control switch\" and starts in charging activation mode. Connect a charger whose voltage is at least 5 V higher than the battery. Many people use the charger they already own, briefly, just to wake the board.",[25,33,34,37],{},[28,35,36],{},"Power button (PB inverter BMS)."," In the off state a short press turns it on. Holding the button for 3 seconds turns it off. The spec sheet also says the button must be pressed once after the wiring is complete.",[25,39,40,43],{},[28,41,42],{},"Activation switch or display."," Some boards come with a small activation button or a display whose switch wakes the BMS. Holding it for a few seconds does the same as the charger.",[10,45,46],{},"A brand new board that was never activated looks exactly like a dead one: no Bluetooth, no LEDs, no current. That is normal.",[14,48,50],{"id":49},"check-the-wiring-order-first","Check the wiring order first",[10,52,53],{},"The BMS takes its own supply from the cells through B- and the balance connector. If one of them is missing, it cannot start, and the order matters. The PB specification describes a strict sequence:",[55,56,57,60,63,66],"ol",{},[25,58,59],{},"Connect B- and P- (or C-), then B+ and P+ where the board has them.",[25,61,62],{},"Plug the cell sampling (balance) connectors from low to high, starting at cell 1.",[25,64,65],{},"Press the button, or connect the charger, to activate.",[25,67,68],{},"Only then connect the load or the charger for normal use.",[10,70,71],{},"To remove the BMS, go in reverse: charger and load first, balance connectors from high to low, and the power cables last. Before plugging the balance connector, measure every pin against B- with a multimeter: each step should add one cell voltage. A swapped or missing lead keeps the board dark or makes it report the wrong cell count.",[14,73,75],{"id":74},"it-worked-before-and-now-it-is-off","It worked before and now it is off",[10,77,78],{},"If the BMS ran for a while and then went dark, it most likely shut itself down on purpose:",[22,80,81,93,99,105],{},[25,82,83,86,87,92],{},[28,84,85],{},"Power off voltage."," When the cells fall below the power off voltage, the BMS switches off completely to stop its own consumption. It does not come back on its own when the load is removed. You need the charger or the button to start it again. Keep power off below UVP, as explained in the ",[88,89,91],"a",{"href":90},"\u002Fguides\u002Fjk-bms-parameters-explained","parameters guide",".",[25,94,95,98],{},[28,96,97],{},"Smart sleep."," With smart sleep enabled, an idle battery can put the BMS to sleep. A charger, a load or the button wakes it.",[25,100,101,104],{},[28,102,103],{},"Switched off from the app."," The control page of the JK app can turn the BMS power off. It looks the same as a shutdown.",[25,106,107,110,111,92],{},[28,108,109],{},"A protection, not a power off."," If the LEDs or the display are on but the battery gives no power, the BMS is running and a protection has opened the MOSFETs. That is a different problem: read the alarms, or see ",[88,112,114],{"href":113},"\u002Fguides\u002Fjk-bms-error-codes","error codes",[10,116,117,118,122],{},"If it switches off and on repeatedly, read the ",[88,119,121],{"href":120},"\u002Fguides\u002Fjk-bms-reboots-power-events","reboots and power events guide",", which shows how this looks in the Detail Log.",[14,124,126],{"id":125},"the-charger-will-not-start-either","The charger will not start either",[10,128,129],{},"A common trap: the BMS is off, so the charge MOSFET is open, so the charger on the battery terminals sees no voltage and refuses to start. Ways out:",[22,131,132,135,138],{},[25,133,134],{},"use a charger or bench supply that can start into zero volts, or one that has a lithium wake function;",[25,136,137],{},"press the activation button or display switch first, then connect the charger;",[25,139,140],{},"with a deeply discharged pack, charge the weakest cells directly with a small bench supply until they are back above the power off voltage, then activate the BMS.",[14,142,144],{"id":143},"when-the-board-itself-is-the-problem","When the board itself is the problem",[10,146,147],{},"If the wiring measures correctly, the cells are above about 2.5 V each and a correct activation still gives no sign of life, the board may be damaged. Reverse polarity on B- and P-, a balance lead connected before B-, or a short on the sampling wires are the usual causes. At that point contact the seller with your model number from the label.",[14,149,151],{"id":150},"faq","FAQ",[153,154,156],"h3",{"id":155},"how-do-i-turn-on-a-new-jk-bms","How do I turn on a new JK BMS?",[10,158,159],{},"Wire it completely, then connect a charger whose voltage is at least 5 V above the pack, or press the power or activation button if your board has one. The BMS starts within a few seconds and Bluetooth becomes visible.",[153,161,163],{"id":162},"why-did-my-jk-bms-turn-off-by-itself","Why did my JK BMS turn off by itself?",[10,165,166],{},"Most often the cells dropped below the power off voltage, smart sleep put it to sleep, or someone switched it off in the app. Each of these needs a charger or the button to start again.",[153,168,170],{"id":169},"how-do-i-wake-up-a-jk-bms-from-sleep","How do I wake up a JK BMS from sleep?",[10,172,173],{},"Connect a charger or a load, or press the button or the display switch. If it does not wake, check whether it shut down on low voltage instead of sleeping.",[153,175,177],{"id":176},"how-do-i-turn-off-a-jk-bms","How do I turn off a JK BMS?",[10,179,180],{},"On PB inverter boards hold the power button for 3 seconds. On boards without a button use the control page of the JK app, or disconnect it in reverse wiring order.",[10,182,183,184,188],{},"Once it is running, ",[88,185,187],{"href":186},"\u002F","connect your BMS"," in the browser to check the cell voltages and the power off and UVP settings in one place.",{"title":190,"searchDepth":191,"depth":191,"links":192},"",3,[193,195,196,197,198,199],{"id":16,"depth":194,"text":17},2,{"id":49,"depth":194,"text":50},{"id":74,"depth":194,"text":75},{"id":125,"depth":194,"text":126},{"id":143,"depth":194,"text":144},{"id":150,"depth":194,"text":151,"children":200},[201,202,203,204],{"id":155,"depth":191,"text":156},{"id":162,"depth":191,"text":163},{"id":169,"depth":191,"text":170},{"id":176,"depth":191,"text":177},"2026-10-14","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.","md",[209,210,211,212,213,214],"jk bms not turning on","jk bms how to turn on","jk bms how to wake up","jk bms not starting","jk bms activation","jk bms power button",{},true,"\u002Fguides\u002Fjk-bms-not-turning-on",[219,220,221,222],"jk-bms-first-setup","jk-bms-reboots-power-events","jk-bms-parameters-explained","jk-bms-error-codes",{"title":5,"description":206},"guides\u002Fjk-bms-not-turning-on",null,"QEkBrYdCS_PxrRKj9Lz5rCq4cisJQgVY1X76G6p2k3w",[228,232,236,240,243,247,251,255,256,260,264,268,273,277,281,285,289,294,299,304,308,312,316,320,324,328,332,335,339,342,346,350,354],{"path":229,"title":230,"description":231,"date":205,"updated":225},"\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":233,"title":234,"description":235,"date":205,"updated":225},"\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":237,"title":238,"description":239,"date":205,"updated":225},"\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":113,"title":241,"description":242,"date":205,"updated":225},"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":244,"title":245,"description":246,"date":205,"updated":225},"\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":248,"title":249,"description":250,"date":205,"updated":225},"\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":252,"title":253,"description":254,"date":205,"updated":225},"\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":217,"title":5,"description":206,"date":205,"updated":225},{"path":257,"title":258,"description":259,"date":205,"updated":225},"\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":261,"title":262,"description":263,"date":205,"updated":225},"\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":265,"title":266,"description":267,"date":205,"updated":225},"\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":269,"title":270,"description":271,"date":272,"updated":225},"\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":274,"title":275,"description":276,"date":272,"updated":225},"\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":278,"title":279,"description":280,"date":272,"updated":225},"\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":282,"title":283,"description":284,"date":272,"updated":225},"\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":286,"title":287,"description":288,"date":272,"updated":225},"\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":290,"title":291,"description":292,"date":293,"updated":225},"\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":295,"title":296,"description":297,"date":298,"updated":225},"\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. 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See factory defaults, how to change them, what to try if one fails, and what to do if lost.",{"path":120,"title":340,"description":341,"date":303,"updated":298},"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":343,"title":344,"description":345,"date":303,"updated":298},"\u002Fguides\u002Fjk-bms-sending-failure","JK BMS Sending failure: Causes and Step-by-Step Fix","JK BMS Sending failure on import? 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