MuscleGrid Lithium Battery (JK BMS) — Fault Codes & Care Guide

01Fault code 01: Single-cell over-discharge (over-release)

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 01 / ERROR 1 shown on the battery LCD (Area 1). MEANING: Single-cell over-discharge (over-release). WHAT TO DO: A cell has discharged too low. Recharge the battery soon; avoid deep discharge. If one cell keeps dropping, that cell is weak — have it checked. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

02Fault code 02: Single-cell overcharge

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 02 / ERROR 2 shown on the battery LCD (Area 1). MEANING: Single-cell overcharge. WHAT TO DO: A cell charged too high. Check the inverter/charger charge-voltage setting matches the battery; if it repeats, the pack needs balancing/service. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

03Fault code 03: Overcurrent (overflow)

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 03 / ERROR 3 shown on the battery LCD (Area 1). MEANING: Overcurrent (overflow). WHAT TO DO: Charge or discharge current is above the limit. Reduce the connected load; check for an overload or a short on the output. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

04Fault code 04: MOS over-temperature

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 04 / ERROR 4 shown on the battery LCD (Area 1). MEANING: MOS over-temperature. WHAT TO DO: The BMS MOSFET is too hot. Reduce load/charging current, improve ventilation, and let it cool before using again. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

05Fault code 05: Battery over-temperature

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 05 / ERROR 5 shown on the battery LCD (Area 1). MEANING: Battery over-temperature. WHAT TO DO: The cells are too hot. Stop using it, let it cool, and improve ventilation. Do not charge in high heat. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

06Fault code 06: Short circuit

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 06 / ERROR 6 shown on the battery LCD (Area 1). MEANING: Short circuit. WHAT TO DO: The output was short-circuited and the BMS cut off. Disconnect immediately, find and fix the short in the wiring, then reconnect. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

07Fault code 07: Internal communication abnormal

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 07 / ERROR 7 shown on the battery LCD (Area 1). MEANING: Internal communication abnormal. WHAT TO DO: BMS internal communication fault. Power-cycle the battery (long-press the white button ~5s to shut down, then press 1-2s to boot). If it persists, it needs service. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

08Fault code 08: Balance wire resistance too high

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 08 / ERROR 8 shown on the battery LCD (Area 1). MEANING: Balance wire resistance too high. WHAT TO DO: A balance/sense wire has too much resistance (loose or corroded connector). Have the balance leads checked/re-seated; service if it continues. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

09Fault code 09: Drop string (cell/series connection lost)

MuscleGrid Smart Battery, JK BMS (model JK-PB1A15-16S10P; 1A active balancer; 8S-16S LiFePO4). FAULT CODE 09 / ERROR 9 shown on the battery LCD (Area 1). MEANING: Drop string (cell/series connection lost). WHAT TO DO: A cell string or sense connection has dropped out. This is a connection fault inside the pack — switch it off and have it inspected/serviced; do not keep using it until fixed. Note: this is a BATTERY display code (not the inverter). Battery app connects over Bluetooth after warranty registration.

full table

The battery display shows the active fault code as a number under the fault icon; multiple faults scroll. Codes: 1 = Single-cell over-release / over-discharge alarm — a cell dropped below the undervoltage limit. Reduce load / recharge.; 2 = Single-cell overcharge alarm — a cell exceeded the overcharge voltage. Stop charging; check charger voltage.; 3 = Overflow / overcurrent alarm — charge or discharge current exceeded the set limit. Reduce load or charger current.; 4 = MOS over-temperature alarm — the BMS MOSFETs are too hot (protect at 100°C). Improve ventilation / reduce current.; 5 = Battery over-temperature alarm — cell temperature too high (protect at 70°C). Stop use, let it cool, check ambient.; 6 = Short-circuit alarm — a short was detected on the output. Disconnect load, check wiring for a dead short.; 7 = Internal communication abnormal alarm — BMS internal comms fault. Restart the BMS; if it persists, it needs service.; 8 = Balance-line resistance too high alarm — a balance/sense wire is loose, corroded or poorly crimped. Re-seat the balance harness.; 9 = Drop string alarm — a cell/series connection is lost (open cell tap). Check the balance leads and cell links; needs service if a link is broken.

Boot, shutdown & display screen

BOOT: after wiring, press the white button on the right of the display for 1-2 seconds. SHUTDOWN: while on, long-press the white button ~5 seconds. Display areas: (1) fault code number under the fault icon; (2) warning icon = abnormal warning; (3) power/SOC % (e.g. 88%); (4) charge/discharge current — a leading '-' means discharging (negative), no '-' means charging; (5) total pack voltage. Power-save: screen sleeps ~10s after no current/keys; stays bright while discharging; a key-press wakes it.

how it works & settings

Uses active (energy-transfer) balancing: energy moves from the higher-voltage cell to the lower one via the board, keeping cells matched — improving range and battery life. Max continuous balance current 1A (model dependent, up to 2A). In the BMS app set battery type first, then cell count, capacity and the balance trigger differential (default 0.01V) — balancing turns on automatically when any two cells differ by more than the set value. Keep balance current ≤ 0.2C of pack capacity. Balancing can be switched OFF on the app's BMS control page if not needed.

Heating function (low-temperature)

Standard resistance-heater / heating-film keeps the pack warm in cold weather so charge/discharge don't fail at low temperature. Design heating current ~4A, switched on the app's BMS control page. Recommended to add a normally-closed 45-65°C temperature switch in series as a secondary cut-off against thermal runaway.

Overcharge (charge overvoltage) protection

If any cell goes over-voltage during charging, the BMS turns charging OFF to protect the cell, and re-enables it after the cell falls to the recovery voltage. LiFePO4 defaults: overcharge protect 3.6V per cell, recover 3.54V per cell. Set on the app's parameter page.

Over-discharge (discharge undervoltage) protection

If any cell drops below the undervoltage limit while discharging, the BMS turns discharge OFF to prevent over-discharge, and re-enables it once cells recover. LiFePO4 defaults: undervoltage protect 2.6V, recover 2.65V, automatic shutdown 2.5V (below this the board powers itself off to save the pack). Recharge to release.

Charge / discharge over-current protection

If charge current exceeds the set continuous charge current for the charge-overcurrent delay, charging is cut and re-enabled after the release time. Same for discharge. LiFePO4 defaults: charge OC delay 3s / release 60s; discharge OC delay 300s / release 60s. Also a charge current-limiting mode holds charge ~10A when over-current.

Over-temperature & low-temperature protection

Charge/discharge over-temperature protection cuts charging or discharging when the sensor reads above the set value and restores below the recovery value. LiFePO4 defaults: charge & discharge over-temp protect 70°C, recover 60°C; MOS over-temp protect 100°C, recover 80°C. Charging low-temp protect -20°C, recover -10°C (use the heating function in very cold areas).

Short-circuit protection

Standard short-circuit protection (delay default 1500µs, release 60s). If it false-trips the FIRST time you connect a charger or a load (in-rush from a charger with high peak current, or a load with large input capacitance), increase the short-circuit protection delay on the app — after confirming the external wiring has no real short.

Intelligent sleep

To save power, the board sleeps when it is in standby (charge/discharge current < 1A for 26 continuous hours). Wake it by pressing the button or by connecting the charger. Can be turned on/off on the app's BMS control page.

Communication (CAN / RS485) & inverter protocol

Has CAN and two RS485 ports. CAN default rate 250K. RS485-1 talks to the inverter — pick the matching inverter brand/protocol in the BMS app. RS485-2 is for connecting battery packs in parallel to a host/PC (default baud 115200). Parallel address is set by the DIP switch, range 0-15.

LiFePO4 default parameters (setpoints)

Per-cell LiFePO4 defaults programmed in the BMS app: balancing start 3.0V; balance current 1-2A; overcharge protect 3.6V, recover 3.54V; undervoltage protect 2.6V, recover 2.65V; auto-shutdown 2.5V; SOC-0% = 2.6V; SOC-100% = 3.5V; balance trigger differential 0.01V; charge OC delay 3s / release 60s; discharge OC delay 300s / release 60s; short-circuit delay 1500µs / release 60s; charge & discharge over-temp 70°C protect / 60°C recover; charge low-temp -20°C protect / -10°C recover; MOS over-temp 100°C protect / 80°C recover.

Specifications

BMS JK-PB1A15-16S10P (JK-Energy Storage Series, active balancer, firmware 15.4.1). Supply voltage 20-70V; standby draw 12mW, operating 1100mW; operating temperature -30 to 70°C; up to 16S (8S/15S/16S); balance current 1-2A; max continuous charge & discharge 100A (10P) / 150A (15P) / 200A (20P); max instantaneous 200/300/400A; board size 300×100×18mm; weight ~1000g. Chemistries supported: LiFePO4, Li-ion (ternary), LTO — set the correct type in the app.

BMS app (Bluetooth) & warranty note

The battery has a Bluetooth BMS app (Android 7+ / iOS) to view status, change parameters and control the charge/discharge switch. Scan the QR in the booklet to install. IMPORTANT (MuscleGrid policy): the customer receives the battery-control app only AFTER registering the product warranty and uploading a product photo at musclegrid.in/warranty.

Device activation & first power-on

Before power-on, check the balance cable is properly connected and P- / B- are correct, and the board is securely fixed to the cells — wrong connection can cause abnormal operation or burning. The board has no power switch; it uses CHARGING ACTIVATION — connect a charger whose voltage is ~2V above the pack, after assembly, to wake the board. It also supports key activation and display activation (plug in the display cable and press the button).

Service contacts (battery)

For battery / BMS service: email [email protected] or [email protected]; phone 9999036254 or 8279619312.

Prime / Thunder Pro / Signature

MuscleGrid LFP batteries come in 3 series sharing the same A+ grade LiFePO4 prismatic cells and steel case; the series sets the BMS/display. PRIME (essential): basic BMS, mobile app, passive cell balancing. THUNDER PRO: JK Smart BMS, LCD display + mobile app, 1A active balancer (best for solar/closed-loop inverter control). SIGNATURE (flagship): touch-screen display on every model, JK Smart BMS, 1A active balancer — plus 51.2V 314Ah and 640Ah towers (8000+ cycle cells, 200A JK BMS, 2A active balancer, up to 32.7 kWh per tower). Models: 25.6V / 48V / 51.2V in 100Ah & 120Ah. Which to pick: Prime = dependable everyday backup at best price; Thunder Pro = solar systems wanting closed-loop control + active balancing; Signature = flagship touch-screen monitoring + large storage.

Thunder Pro specifications (48V & 51.2V, 120Ah)

Thunder Pro 48V: 15S, 48.0V nominal, 120Ah, 5.76 kWh, max charge 54.7V, discharge cut-off 40.5V, std/max charge 50A/100A, max continuous discharge 100A (200A instantaneous), 6000+ cycles @80% DoD, charge temp 0-55°C, discharge -20-55°C, M8 terminals torqued 10-12 N·m, indoor floor/rack, upright. Thunder Pro 51.2V: 16S, 51.2V, 120Ah, 6.14 kWh, max charge 58.4V, cut-off 43.2V. Warranty 5 years, 1-time replacement. Amazon ASIN: 48V = B0D2GMQ8FR, 51.2V = B0DVJ14Z9B (Signature 51.2V 314Ah = B0H72K78Z2).

Inverter settings for the battery (closed-loop)

Set the inverter for a MuscleGrid LFP pack. 48V model: battery type Lithium/LFP (or 'USE' custom); bulk/absorption 54.0V; float 53.6V; low-voltage cut-off 42.0V; max charge current 50A recommended (100A max); BMS protocol CAN 250K or RS485 (select brand in app). 51.2V model: bulk/absorption 57.6V; float 57.0V; cut-off 44.8V. With CAN/RS485 closed-loop active, the inverter follows the BMS's requested voltage/current automatically — these values are the safety fallback.

site preparation & cabling

Inspect on arrival (case, terminals, display for transit damage — do NOT install a damaged pack, call support; keep the wooden crate until commissioning is done). Position: dry, ventilated, level indoor spot away from heat, sunlight and water; upright on floor or rack; ≥100mm clearance on all sides; display facing you; heavy — lift with two people. Fit a 125A DC MCB or fuse on the POSITIVE line between battery and inverter (this is the service disconnect — leave OFF until commissioning). Cables: 25-35 mm² copper with crimped M8 lugs, as short as possible (≤2m), both runs equal length, route + and - together, avoid sharp bends. Professional electrician recommended.

Connect & commission (order of steps)

With inverter and MCB OFF: connect positive (+, red) to the battery FIRST, then negative (-, black); torque M8 bolts 10-12 N·m; never bridge the two terminals with a tool. For closed-loop, connect the inverter's BMS port to CAN or RS485-1 on the battery (RS485-2 is only for pack-to-pack parallel linking); select the inverter protocol in the app. Power-on order: boot the BMS (white button 1-2s) → switch the MCB on → start the inverter; verify voltage/current/SOC on the LCD or app BEFORE applying load. Then set the inverter parameters and charge the pack to 100% before its first discharge so the SOC meter calibrates.

Parallel connection rules (up to 16 packs)

MuscleGrid LFP packs connect in PARALLEL only, up to 16 packs. Rules: parallel IDENTICAL packs only — same model, capacity and firmware (never mix 48V with 51.2V). Charge every pack to 100% individually before connecting them. Run equal-length cables from each pack to a common busbar — never daisy-chain the power path. Link packs with the RS485-2 ports and set a unique DIP-switch address on each (0-15); address 0 is the master — connect it to the inverter. The BMS parallel current-limiting protects a newly added pack, but matched SOC keeps performance best.

NEVER connect packs in series (critical)

NEVER connect MuscleGrid LFP packs in SERIES — these models are PARALLEL-ONLY. Series connection VOIDS the warranty and can damage the BMS.

Warranty terms (5-year)

5-year warranty with 1-time hassle-free replacement — a local technician visits, diagnoses and swaps on the spot. Covers manufacturing defects and BMS failures. EXCLUDES physical damage, water ingress, unauthorised servicing, and series connection. Register within 30 days at newcrm.musclegrid.in and keep the invoice with the booklet — both are needed for a claim.

Safety warnings

Never short-circuit or reverse polarity — keep metal tools, jewellery and loose wiring away from the terminals. Never connect in series (parallel, identical models only). Do not open the case (no user-serviceable parts; opening voids warranty). Keep away from fire and water; never incinerate. Charge only between 0-55°C (the BMS blocks charging below -20°C to protect the cells). Disconnect before servicing: switch off the inverter, then the MCB, then shut the BMS down. Keep away from children. Recycle end-of-life packs via MuscleGrid or an authorised e-waste recycler.

Care & long-term storage

For long storage keep the pack at ~50% SOC in a cool, dry place and top up every 3 months. Wipe with a dry cloth only — no solvents, no water jets.

what the customer should do

When the fault icon lights, the number in display Area 1 is the active fault. Actions: 1 Cell over-discharge → remove load and recharge immediately. 2 Cell overcharge → check the inverter charge voltage against the settings. 3 Overcurrent → reduce the connected load, auto-recovers after release time. 4 MOS over-temperature → improve ventilation, let the pack cool. 5 Battery over-temperature → stop charge/discharge until temperature normalises. 6 Short-circuit → disconnect the load, inspect wiring before restart. 7 Internal communication abnormal → restart the BMS; if it persists, call support. 8 Balance-line resistance too high → service required, contact support. 9 Drop string (cell disconnection) → shut down and contact support, do NOT continue use. If a fault won't clear: note the code, switch the MCB off and call +91 99990 36254 (24x7, video-call assistance) or [email protected].