[{"data":1,"prerenderedAt":427},["ShallowReactive",2],{"guide-en-jk-bms-ocp-scp-settings":3,"guides-en":368},{"id":4,"title":5,"body":6,"date":346,"description":347,"extension":348,"keywords":349,"meta":357,"navigation":358,"path":359,"related":360,"seo":364,"stem":365,"updated":366,"__hash__":367},"guides_en\u002Fguides\u002Fjk-bms-ocp-scp-settings.md","JK BMS Overcurrent Protection Settings: OCP and SCP Guide",{"type":7,"value":8,"toc":329},"minimark",[9,13,18,21,24,47,50,54,185,188,192,201,212,215,218,222,225,237,240,244,247,251,254,257,261,269,272,290,294,299,302,306,309,313,320],[10,11,12],"p",{},"JK BMS overcurrent protection settings are two current limits, each with a delay and a recovery time, plus a separate short circuit protection (SCP). Set Max charge current and Max discharge current to what your cells, cables and fuse can carry continuously, and always below the BMS rating. Leave the SCP fields at the factory value unless you know your firmware.",[14,15,17],"h2",{"id":16},"how-the-protections-work","How the protections work",[10,19,20],{},"The BMS measures pack current all the time. When the current stays above a limit for longer than its delay, the BMS opens the charge or discharge MOSFETs. It keeps them open for the recovery time, then closes them again.",[10,22,23],{},"There are three layers:",[25,26,27,35,41],"ul",{},[28,29,30,34],"li",{},[31,32,33],"strong",{},"Charge OCP."," Max charge current, Charge OCP delay, Charge OCP recovery time.",[28,36,37,40],{},[31,38,39],{},"Discharge OCP."," Max discharge current, Discharge OCP delay, Discharge OCP recovery time.",[28,42,43,46],{},[31,44,45],{},"Short circuit protection."," Short circuit protection delay and Short circuit recovery time. This one reacts in microseconds, far faster than OCP.",[10,48,49],{},"OCP is for overload. SCP is for a dead short.",[14,51,53],{"id":52},"jk-bms-overcurrent-protection-settings-table","JK BMS overcurrent protection settings table",[55,56,57,76],"table",{},[58,59,60],"thead",{},[61,62,63,67,70,73],"tr",{},[64,65,66],"th",{},"Parameter (as in the app and editor)",[64,68,69],{},"Unit",[64,71,72],{},"Typical range",[64,74,75],{},"Note",[77,78,79,94,108,121,134,147,160,174],"tbody",{},[61,80,81,85,88,91],{},[82,83,84],"td",{},"Max charge current",[82,86,87],{},"A",[82,89,90],{},"0.3C to 1C of pack capacity",[82,92,93],{},"Never above the BMS rating. Field limit in the file is 400 A.",[61,95,96,99,102,105],{},[82,97,98],{},"Charge OCP delay",[82,100,101],{},"s",[82,103,104],{},"2 to 5",[82,106,107],{},"Longer values tolerate short charger spikes.",[61,109,110,113,115,118],{},[82,111,112],{},"Charge OCP recovery time",[82,114,101],{},[82,116,117],{},"30 to 120",[82,119,120],{},"60 s is a typical value.",[61,122,123,126,128,131],{},[82,124,125],{},"Max discharge current",[82,127,87],{},[82,129,130],{},"0.5C to 1C of pack capacity",[82,132,133],{},"Limited by cells, busbars, fuse and cables. Field limit is 600 A.",[61,135,136,139,141,144],{},[82,137,138],{},"Discharge OCP delay",[82,140,101],{},[82,142,143],{},"10 to 300",[82,145,146],{},"300 s is the editor's typical value. Longer rides through inverter surges.",[61,148,149,152,154,157],{},[82,150,151],{},"Discharge OCP recovery time",[82,153,101],{},[82,155,156],{},"60 to 120",[82,158,159],{},"60 to 70 s is typical.",[61,161,162,165,168,171],{},[82,163,164],{},"Short circuit protection delay",[82,166,167],{},"µs",[82,169,170],{},"no recommended range",[82,172,173],{},"Depends on firmware, see below.",[61,175,176,179,181,183],{},[82,177,178],{},"Short circuit recovery time",[82,180,101],{},[82,182,170],{},[82,184,173],{},[10,186,187],{},"These ranges come from the recommendation table in the editor, which is built from the JK manual, Gobel Power, Clever Solar and forum reports. They are ranges, not a single correct value.",[14,189,191],{"id":190},"sizing-the-current-limits","Sizing the current limits",[10,193,194,195,200],{},"JK Preset Studio derives current limits from the cell C-rate and the pack capacity. For LiFePO4 the three wear levels on the ",[196,197,199],"a",{"href":198},"\u002Fpresets","presets page"," use these C-rates for charge and discharge:",[25,202,203,206,209],{},[28,204,205],{},"Gentle: 0.3C charge, 0.5C discharge.",[28,207,208],{},"Medium: 0.5C charge, 0.7C discharge.",[28,210,211],{},"Hard: 1C charge, 1C discharge.",[10,213,214],{},"The result is C-rate times capacity in Ah, rounded to whole amps, never below 1 A. Then the editor caps it by the BMS rating. The rating is read from the model name: the digits before a trailing P are multiplied by 10. A JK-PB2A16S20P gives 200 A, a model ending in 15P gives 150 A. If the model has no such suffix, the rating is unknown and no cap is applied.",[10,216,217],{},"Example: a 280Ah pack on the medium level gives 140 A charge and 196 A discharge. On a 20P board both stay under 200 A. A 1C hard preset on a 314Ah pack would ask for 314 A, so a 20P board caps it at 200 A.",[14,219,221],{"id":220},"sizing-ocp-for-an-inverter","Sizing OCP for an inverter",[10,223,224],{},"Separate continuous current from peak current. The Max discharge current is the continuous limit. Inverters and motors draw a short surge at start-up, often two to three times the rated load.",[226,227,228,231,234],"ol",{},[28,229,230],{},"Take the inverter continuous power and divide by the battery voltage. Add 10 to 20 percent for efficiency losses and low-voltage operation.",[28,232,233],{},"Set Max discharge current above that value, but below the weakest part of the system.",[28,235,236],{},"Use Discharge OCP delay to ride through surges. A longer delay lets a start-up spike pass. The 300 s default is generous. 10 s gives quicker protection for small systems.",[10,238,239],{},"Inrush into inverter capacitors can trip SCP instead of OCP. Users sometimes raise the SCP delay, but precharging the inverter is the better fix.",[14,241,243],{"id":242},"cable-and-fuse-coordination","Cable and fuse coordination",[10,245,246],{},"The BMS limit should be the lowest setting in a chain. Cables must carry more than the BMS limit continuously, and the fuse should be rated above the BMS limit but below the cable ampacity. That way the BMS trips first for overloads, and the fuse only acts when the BMS fails or a short outruns it. Cell ratings matter too: Max charge current should respect the cell rating, for example 0.5C for EVE LFP cells.",[14,248,250],{"id":249},"what-happens-on-a-trip","What happens on a trip",[10,252,253],{},"If the overload is still there after the recovery time, the BMS trips again.",[10,255,256],{},"On charge OCP or a short circuit, the PCL module (parallel current limiter) can limit the current to about 10 A instead of cutting it. Keep PCL enabled when connecting packs in parallel. With Disable PCL set, the BMS cuts charging and retries after about 60 s.",[14,258,260],{"id":259},"scp-delay-and-firmware","SCP delay and firmware",[10,262,263,264,268],{},"Do not copy SCP values between files. Firmware V19 and newer stores a small number here, 5 by default, and rejects anything above 50 on import. Older V15 files hold values like 1500 µs. Importing such a file onto a V19 device fails with \"This parameter does not apply to the connected device. (Sending failure)\". This was verified on a JK-PB2A16S20P with firmware 19.26. See ",[196,265,267],{"href":266},"\u002Fguides\u002Fjk-bms-sending-failure","what to do about Sending failure",".",[10,270,271],{},"For that reason the editor has no recommended range for SCP delay and recovery. The same device also rejected 60 s for the recovery time. Change SCP in the JK app on the device, or leave the factory value. The editor flags an SCP delay above 50 on V19 as an error.",[10,273,274,275,279,280,284,285,289],{},"Overcurrent and short-circuit trips, and the peak currents around them, show up in the Detail Log. Load it on the ",[196,276,278],{"href":277},"\u002Flogs","log analysis page"," and attach your .jkcfg, and the page flags peaks within 10% of your limits. The ",[196,281,283],{"href":282},"\u002Fguides\u002Fjk-bms-detail-log","JK BMS Detail Log"," guide explains the analysis, and ",[196,286,288],{"href":287},"\u002Fguides\u002Fjk-bms-log-messages-explained","what each log message means"," decodes the message text.",[14,291,293],{"id":292},"faq","FAQ",[295,296,298],"h3",{"id":297},"what-is-a-good-jk-bms-charge-current-limit","What is a good JK BMS charge current limit?",[10,300,301],{},"Stay at or below the cell rating and the BMS rating. For LiFePO4, 0.3C to 0.5C is gentle and common. A 280Ah pack at 0.5C gives 140 A.",[295,303,305],{"id":304},"should-the-ocp-delay-be-long-or-short","Should the OCP delay be long or short?",[10,307,308],{},"Short delays protect better. Long delays tolerate surges. Use 2 to 5 s for charge, and a longer delay on discharge only if your inverter or motor has a start-up surge.",[295,310,312],{"id":311},"can-i-change-scp-delay-in-the-file","Can I change SCP delay in the file?",[10,314,315,316,268],{},"Only if you know the firmware stores that value the way you expect. On V19 the value must be 50 or lower. Otherwise change it in the JK app. For the file basics, see ",[196,317,319],{"href":318},"\u002Fguides\u002Fjk-bms-export-import-settings","export and import of JK BMS settings",[10,321,322,326,327,268],{},[196,323,325],{"href":324},"\u002F","Connect your BMS or open your .jkcfg"," in the editor to check these currents against your model's rating before anything is written, or start from a ready level on the ",[196,328,199],{"href":198},{"title":330,"searchDepth":331,"depth":331,"links":332},"",3,[333,335,336,337,338,339,340,341],{"id":16,"depth":334,"text":17},2,{"id":52,"depth":334,"text":53},{"id":190,"depth":334,"text":191},{"id":220,"depth":334,"text":221},{"id":242,"depth":334,"text":243},{"id":249,"depth":334,"text":250},{"id":259,"depth":334,"text":260},{"id":292,"depth":334,"text":293,"children":342},[343,344,345],{"id":297,"depth":331,"text":298},{"id":304,"depth":331,"text":305},{"id":311,"depth":331,"text":312},"2026-10-02","JK BMS overcurrent protection settings explained: charge and discharge OCP limits, delays, recovery times and SCP, with ranges and sizing for inverters.","md",[350,351,352,353,354,355,356],"jk bms overcurrent protection settings","jk bms ocp delay","jk bms scp delay","jk bms charge current limit","jk bms discharge ocp","jk bms short circuit protection","jk bms charge ocp recovery",{},true,"\u002Fguides\u002Fjk-bms-ocp-scp-settings",[361,362,363],"jk-bms-parameters-explained","jk-bms-detail-log","jk-bms-log-messages-explained",{"title":5,"description":347},"guides\u002Fjk-bms-ocp-scp-settings","2026-10-04","92-E-5Q6CC9CyonyUpscPuokqd9_iZQj2x9jElD3uuE",[369,374,378,382,385,388,392,395,399,400,404,408,412,415,419,423],{"path":370,"title":371,"description":372,"date":366,"updated":373},"\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.",null,{"path":375,"title":376,"description":377,"date":346,"updated":366},"\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.",{"path":379,"title":380,"description":381,"date":346,"updated":373},"\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":282,"title":383,"description":384,"date":346,"updated":366},"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":318,"title":386,"description":387,"date":346,"updated":366},"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":389,"title":390,"description":391,"date":346,"updated":366},"\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":287,"title":393,"description":394,"date":346,"updated":373},"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":396,"title":397,"description":398,"date":346,"updated":366},"\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":359,"title":5,"description":347,"date":346,"updated":366},{"path":401,"title":402,"description":403,"date":346,"updated":366},"\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":405,"title":406,"description":407,"date":346,"updated":366},"\u002Fguides\u002Fjk-bms-password","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":346,"updated":366},"\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":266,"title":413,"description":414,"date":346,"updated":366},"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":416,"title":417,"description":418,"date":346,"updated":366},"\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":420,"title":421,"description":422,"date":346,"updated":373},"\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":424,"title":425,"description":426,"date":346,"updated":366},"\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.",1791151315764]