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Fault code index · Pylontech US-series & Force H2 batteries

Pylontech Fault Code Index

Every Pylontech battery alarm, BMS protection event, and LED indicator state — what each fault means, the most likely cause, and what to do next. Pylontech batteries are battery-only — faults also surface through your paired inverter's monitoring platform. Covers US2000C, US3000C, US5000, and Force H2.

Battery-only — faults surface through your inverter LED indicators and BMS protection events US2000C · US3000C · US5000 · Force H2

Pylontech Fault Code Index

Every Pylontech battery alarm, BMS protection event, and LED indicator state — what each fault means, the most likely cause, and what to do next. Pylontech batteries are battery-only — faults also surface through your paired inverter's monitoring platform. Covers US2000C, US3000C, US5000, and Force H2.
  • Battery-only — faults surface through your inverter
  • LED indicators and BMS protection events
  • US2000C · US3000C · US5000 · Force H2
Pylontech battery fault you can't resolve?

If your Pylontech battery is in protection mode or showing alarms through your inverter, a remote diagnostic identifies the cause and recommends the fix — usually within 30 minutes.

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13 Trustpilot reviews
Trustpilot Google

I have a GivEnergy system consisting of two batteries, two inverters and a controlling EMS (Energy Management System) which has not worked since Nov 2025. After six months I discovered Solar Tech Support, reached out to them and Ron phoned me back – how often do you get that service? Could not be more helpful – worked directly with me over the phone, outside what I would call normal working hours. Lucid explanations and we were able to discuss the issues and history using camera and email history. As this was a very rare setup, Ron was able to access an EMS expert in the field to confirm the solution. One sunny day in, I am now only paying for standing charge and a few pence for spikes in grid consumption while battery catches up with house demand.

Ian · May 2026 Trustpilot

When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.

Sree · May 2026 Trustpilot

Ron want out of is way to help, nothing was to much. He was very thorough in what he did Very knowledgeable I would highly recommend Ron and his company He did a fantastic job for me. if you have any problems, he'll do his best to help you out and resolve your problem. I wouldn't hesitate to recommend them

Dennis Brown · May 2026 Trustpilot

Ron took me through a diagnostic to confirm my GivEnergy Inverter had a fault. A common one as it turns out with the AC Inverter. As GivEnergy is defunct there is no immediate fix, aside from sourcing 2nd hand replacement. It may be that a fix becomes available over the summer which would make a lot of GivEnergy customers happy (Again)

Tony Deacon · May 2026 Trustpilot

Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone

Phill · May 2026 Trustpilot

I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues

michael fairhurst · May 2026 Trustpilot

Contacted Solar Tech Support in desperation. After explaining the issues I had with my system a diagnosis was made and a solution proposed. Fantastic service, even contacted a manufacturer to arrange replacement parts for me. Great communications, explained all they were doing and what I had to do, clearly and precisly. Followed up to confirm all was ok. Excellent service.

Mr Machin · May 2026 Trustpilot

After GivEnergy went into liquidation, just my luck, my battery started playing up (internal board crashed). Contacted my installer - not interested! Found Solar tech support on a Google search. Sooo glad I found this company! Ron is extremely helpful and has plenty of experience. He soon confirmed what the fault was, and helped me to get my system up and running again. Now moved my GivEnergy account to Solar tech support, and will definitely use again if I have more issues. Unusual to find such a helpful company in these times, no morons reading scripts, just direct contact with the engineer.

Keith Ballard · Apr 2026 Trustpilot

Contacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.

Hugh Speirs · Apr 2026 Trustpilot

Ron is a super star. Two months ago my GivEnergy battery failed a firmware upgrade leaving it a brick. My installer couldn't/wouldn't fix it. GivEnergy couldn't/wouldn't fix it. Then they went into administration and all hope was lost. A flurry of emails later and Ron had diagnosed the fault (failed USB flash drive, something I'd suspected) and talked me through resolving it. Two months of nothing resolved in about 3 hours. It's great to work with someone who pays attention to the details, knows that they're doing (not just following a script) and gets stuff sorted without a fuss or up-charging.

Christopher · Apr 2026 Trustpilot

I can add to the list of customers who had already 'given up' on GivEnergy due to their appalling customer service, and that was before they went into administration (their Trustpilot reviews don't lie!). So you can imagine my desperation when, having changed my ISP and my Inverter, predictably, proving to be the only device that didn't connect automatically to my new network, I found zero prospect of any customer support with GivEnergy having called in the administrators just five days earlier! The salvation came from Solar Tech Support. My IT advisor stumbled across their web site and some very helpful tips for beleaguered GivEnergy customers, as well as an offer to provide direct assistance. Nothing ventured, I decided to drop them an E-Mail, with very low expectations based on my experience of GivEnergy customer support. Within an hour Ron had responded with some pin point advice, and after a few exchanges of E-Mails he had nailed the problem, enabling the combined efforts of my IT advisor and solar installer to resolve it and reconnect my Inverter. Thank you Solar Tech Support, and Ron in particular, for coming to the aid of a deserted and despondent GivEnergy customer. Expert, razor sharp advice and first class customer service, even though I wasn't officially a customer.

customer · Apr 2026 Trustpilot

This company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing . If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.

Andy Thomas · Apr 2026 Trustpilot

I sent a message on their website regarding a problem I have on my Givenergy system. Although not supplied by Ronald, I thought it was worth an email. Within the hour on a Saturday, he phoned and we discussed the problem. He logged in remotely and gave excellent advice. I'm too far away for his on-site help but he did diagnose the problem and was happy also to chat through my thoughts about an upcoming solar/battery install I'm planning. Great bloke.... if only he was nearer!

Philip · Apr 2026 Trustpilot

I have a GivEnergy system consisting of two batteries, two inverters and a controlling EMS (Energy Management System) which has not worked since Nov 2025. After six months I discovered Solar Tech Support, reached out to them and Ron phoned me back – how often do you get that service? Could not be more helpful – worked directly with me over the phone, outside what I would call normal working hours. Lucid explanations and we were able to discuss the issues and history using camera and email history. As this was a very rare setup, Ron was able to access an EMS expert in the field to confirm the solution. One sunny day in, I am now only paying for standing charge and a few pence for spikes in grid consumption while battery catches up with house demand.

Ian · May 2026 Trustpilot

When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.

Sree · May 2026 Trustpilot

Ron want out of is way to help, nothing was to much. He was very thorough in what he did Very knowledgeable I would highly recommend Ron and his company He did a fantastic job for me. if you have any problems, he'll do his best to help you out and resolve your problem. I wouldn't hesitate to recommend them

Dennis Brown · May 2026 Trustpilot

Ron took me through a diagnostic to confirm my GivEnergy Inverter had a fault. A common one as it turns out with the AC Inverter. As GivEnergy is defunct there is no immediate fix, aside from sourcing 2nd hand replacement. It may be that a fix becomes available over the summer which would make a lot of GivEnergy customers happy (Again)

Tony Deacon · May 2026 Trustpilot

Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone

Phill · May 2026 Trustpilot

I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues

michael fairhurst · May 2026 Trustpilot

Contacted Solar Tech Support in desperation. After explaining the issues I had with my system a diagnosis was made and a solution proposed. Fantastic service, even contacted a manufacturer to arrange replacement parts for me. Great communications, explained all they were doing and what I had to do, clearly and precisly. Followed up to confirm all was ok. Excellent service.

Mr Machin · May 2026 Trustpilot

After GivEnergy went into liquidation, just my luck, my battery started playing up (internal board crashed). Contacted my installer - not interested! Found Solar tech support on a Google search. Sooo glad I found this company! Ron is extremely helpful and has plenty of experience. He soon confirmed what the fault was, and helped me to get my system up and running again. Now moved my GivEnergy account to Solar tech support, and will definitely use again if I have more issues. Unusual to find such a helpful company in these times, no morons reading scripts, just direct contact with the engineer.

Keith Ballard · Apr 2026 Trustpilot

Contacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.

Hugh Speirs · Apr 2026 Trustpilot

Ron is a super star. Two months ago my GivEnergy battery failed a firmware upgrade leaving it a brick. My installer couldn't/wouldn't fix it. GivEnergy couldn't/wouldn't fix it. Then they went into administration and all hope was lost. A flurry of emails later and Ron had diagnosed the fault (failed USB flash drive, something I'd suspected) and talked me through resolving it. Two months of nothing resolved in about 3 hours. It's great to work with someone who pays attention to the details, knows that they're doing (not just following a script) and gets stuff sorted without a fuss or up-charging.

Christopher · Apr 2026 Trustpilot

I can add to the list of customers who had already 'given up' on GivEnergy due to their appalling customer service, and that was before they went into administration (their Trustpilot reviews don't lie!). So you can imagine my desperation when, having changed my ISP and my Inverter, predictably, proving to be the only device that didn't connect automatically to my new network, I found zero prospect of any customer support with GivEnergy having called in the administrators just five days earlier! The salvation came from Solar Tech Support. My IT advisor stumbled across their web site and some very helpful tips for beleaguered GivEnergy customers, as well as an offer to provide direct assistance. Nothing ventured, I decided to drop them an E-Mail, with very low expectations based on my experience of GivEnergy customer support. Within an hour Ron had responded with some pin point advice, and after a few exchanges of E-Mails he had nailed the problem, enabling the combined efforts of my IT advisor and solar installer to resolve it and reconnect my Inverter. Thank you Solar Tech Support, and Ron in particular, for coming to the aid of a deserted and despondent GivEnergy customer. Expert, razor sharp advice and first class customer service, even though I wasn't officially a customer.

customer · Apr 2026 Trustpilot

This company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing . If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.

Andy Thomas · Apr 2026 Trustpilot

I sent a message on their website regarding a problem I have on my Givenergy system. Although not supplied by Ronald, I thought it was worth an email. Within the hour on a Saturday, he phoned and we discussed the problem. He logged in remotely and gave excellent advice. I'm too far away for his on-site help but he did diagnose the problem and was happy also to chat through my thoughts about an upcoming solar/battery install I'm planning. Great bloke.... if only he was nearer!

Philip · Apr 2026 Trustpilot
How to read Pylontech faults. Pylontech batteries do not display numbered fault codes on a screen. Instead, the ALM LED on the front panel indicates alarm or protection mode. The specific fault type is identified through your paired inverter's monitoring platform (GivEnergy portal, Victron VRM, Solis Cloud, Fox Cloud, etc.) or by connecting to the battery via Pylontech BatteryView software over the console port using a USB cable.
LED indicator states

The front panel LEDs are the primary way to identify Pylontech battery status. The RUN LED shows operating state, the ALM LED shows fault conditions, and the SOC LEDs show charge level. These states apply to all US-series models.

RUN LED — solid green Normal · charging active
The battery is operating normally and is actively charging. One of the SOC LEDs will flash to indicate the current charge level. This is the expected state when the inverter is sending charge current to the battery.
RUN LED — slow flash (~3.5s) Normal · idle / standby
The battery is powered on and communicating with the inverter but not actively charging or discharging. This is normal during periods of low demand when the inverter does not need battery power.
RUN LED — fast flash (~1.5s) Normal · discharging active
The battery is actively discharging — providing power to the home or backing up loads. The SOC LEDs show the current charge level. This is normal during evening self-consumption or during a power cut if EPS is enabled.
ALM LED — flashing red (~1.5s) Warning · approaching limit
The battery BMS has detected a parameter approaching its operational limit — this could be temperature, voltage, or current. The battery continues to operate normally under this state. Check your inverter's alarm log for the specific parameter triggering the warning. Common triggers include high ambient temperature in summer or a cell voltage nearing the upper limit during charge.
ALM LED — solid red, all others off ⚠ Protection mode — battery shut down
The BMS has shut down charge and discharge to protect the battery cells. The battery will not accept or deliver power in this state. Common triggers include cell overvoltage, cell undervoltage, overcurrent, overtemperature, or a short circuit. Check the inverter alarm log for the specific protection type, then power cycle the battery — switch off, wait 60 seconds, switch back on. If protection mode returns immediately, the underlying cause needs diagnosis.
All LEDs off — battery appears dead ⚠ Deep sleep or hardware fault
No LEDs lit means the battery has no power or has entered deep sleep protection after being fully discharged. Check the breaker or power button is on. If the battery was deeply discharged (left at 0% for an extended period), it may need a controlled bench recharge to recover. Do not attempt to force-charge a battery showing 0V without professional guidance — this can be dangerous if cells have degraded.
Voltage protection alarms

Voltage alarms trigger when individual cell voltages or the total module voltage exceeds safe limits. These are the most common Pylontech protection events, often caused by incorrect charge settings or cell imbalance.

Cell overvoltage protection ⚠ Protection mode — charge stopped
One or more cells have exceeded the safe voltage limit (typically above 3.65V per cell or 54V module voltage). The BMS cuts off charging. Usually caused by the inverter's charge voltage being set too high — check the battery charge voltage setting in your inverter matches Pylontech's recommended parameters (typically 52.0–53.5V for a 48V stack). Cell imbalance can also cause one cell to overshoot while others are normal — this requires balancing.
Cell overvoltage warning ALM flashing · charge continuing
A cell is approaching the overvoltage threshold but has not yet triggered protection. The battery continues charging but the BMS is signalling that it is close to its limit. If your inverter supports it, enable the "limit managed battery charge voltage" feature and reduce the charge voltage slightly. This gives cells time to balance before hitting the hard limit.
Cell undervoltage protection ⚠ Protection mode — discharge stopped
One or more cells have dropped below the safe minimum voltage (typically below 2.5V per cell or 44V module voltage). The BMS cuts off discharge to prevent permanent cell damage. This happens when the battery is discharged too deeply — often because the inverter's low-voltage cutoff is set incorrectly or the battery was left in a discharged state for an extended period. Charge the battery from AC to recover.
Cell undervoltage warning ALM flashing · discharge continuing
A cell is approaching the undervoltage threshold. The battery continues discharging but the BMS is signalling that charge is critically low. The inverter should stop drawing power before the hard cutoff triggers. If you see this warning regularly, your inverter's minimum SOC or discharge cutoff voltage may be set too low.
Module voltage imbalance Multi-unit stack · SOC mismatch
In a multi-battery stack, the voltage or SOC of individual modules has diverged significantly. One module reaches full or empty before the others. Usually caused by mixing batteries of different ages or capacities, or by a faulty cell in one module dragging its voltage down. Check individual module voltages through BatteryView or your inverter's per-battery monitoring. Persistent imbalance may require isolating the affected module.
Current protection alarms

Current alarms trigger when charge or discharge current exceeds the battery's rated limits. The US5000 supports up to 100A continuous — exceeding this causes the BMS to shut down the affected direction.

Charge overcurrent protection ⚠ Protection mode — charge stopped
Charge current has exceeded the battery's maximum charge rate. Each US5000 module supports 25A charge (100A for a 4-unit stack at recommended max). This can occur if the inverter's charge current limit is set higher than the battery can accept, or if solar generation spikes and the inverter sends all available power to the battery. Reduce the charge current limit in your inverter settings.
Discharge overcurrent protection ⚠ Protection mode — discharge stopped
Discharge current has exceeded the battery's maximum discharge rate. Each US5000 module supports 25A continuous discharge. A sudden high-power load — such as a kettle, immersion heater, or oven — on the backed-up circuit can exceed the battery's discharge capability, especially with a single module. Add more modules to increase discharge capacity, or remove high-power loads from the backed-up circuit.
Short circuit protection ⚠ Immediate shutdown — do not restart
The BMS has detected a short circuit on the battery output and shut down immediately. Do not attempt to restart the battery without first identifying the cause. Check the DC cables between battery and inverter for damage, exposed conductors, or loose connections. If cables are intact, the short may be internal to the inverter's battery input circuit. Requires professional inspection before reconnecting.
Temperature alarms

Temperature alarms protect the lithium cells from operating outside their safe range. Pylontech US-series batteries operate between 0°C and 50°C for discharge and 0°C to 45°C for charge — exceeding these limits triggers protection.

Charge overtemperature protection Charge stopped · discharge may continue
Internal cell temperature has exceeded the safe limit for charging (typically above 45°C). The BMS stops charge but may allow discharge to continue. Common in summer when batteries are installed in enclosed garages, lofts, or utility cupboards without ventilation. Improve airflow around the battery stack — leave at least 100mm clearance on all sides and consider adding a small extraction fan in enclosed spaces.
Discharge overtemperature protection Full shutdown · above 50°C
Cell temperature has exceeded the safe limit for discharge (typically above 50°C). Both charge and discharge are stopped. The battery must cool before it will resume operation. If this happens repeatedly, the installation location is unsuitable — batteries should not be in direct sunlight, next to heat sources (boilers, hot water cylinders), or in unventilated roof spaces.
Low temperature charging protection Charge stopped · below 0°C
Cell temperature is below 0°C and the BMS has stopped charging to prevent lithium plating — a permanent and dangerous form of cell degradation. Common in unheated garages and outbuildings during winter. The battery will resume charging once temperature rises above 0°C. Do not attempt to bypass this protection. If the battery is in a location that regularly falls below freezing, consider relocating it to a warmer space.
Temperature sensor fault BMS internal · sensor disconnected
The BMS cannot read one or more internal temperature sensors. This may cause the battery to enter protection mode as a precaution since it cannot verify the cells are within a safe temperature range. This is a hardware fault inside the battery and requires professional inspection or warranty replacement.
Communication faults

Communication faults are the most common Pylontech issue in UK installations. These appear when the inverter cannot talk to the battery BMS over CAN or RS485 — and are often caused by incorrect cabling rather than a fault with the battery itself.

Battery communication fault (CAN) Inverter shows: BMS Lost / Batt Comm Fail
The inverter cannot communicate with the Pylontech battery over the CAN bus. Check: the communication cable is plugged into the CAN port on the master battery (not RS485), the correct battery type/protocol is selected in the inverter settings, the cable pinout matches your inverter brand (many supplied cables are wired for one inverter only), and the DIP switches on the battery are set for CAN mode. Inverter pairing guide →
Battery communication fault (RS485) Inverter shows: No Battery / BMS Error
Some inverters communicate with Pylontech over RS485 instead of CAN. Check the cable is in the RS485 port (not CAN), the DIP switches are set for RS485 mode, and the baud rate matches. RS485 wiring is polarity-sensitive — if the A and B pins are swapped, communication fails silently. Try swapping the A/B wires at one end if the connection was working previously.
Master battery not set Multi-unit stack · no CAN output
In a multi-battery stack, only the master battery communicates with the inverter. If no battery is set as master, the inverter receives no data. On US-series batteries, the master unit is the one with the CAN/RS485 communication cable connected to the inverter. On newer units, the DIP switch or link cable configuration determines the master. Check that the top or designated master unit has the communication cable fitted.
Inter-module link cable fault Stack comm · link cables between units
In a stacked configuration, the short link cables between battery modules allow the master to communicate with each slave. A loose or faulty link cable causes the master to lose sight of one or more modules. The inverter may show reduced capacity or intermittent communication drops. Check each link cable is firmly seated in the correct port on each module. Replace any visibly damaged cables.
Module & stack faults

Faults specific to multi-module stacks and individual module hardware — internal BMS failures, firmware issues, and charge profile problems that affect the battery independently of the inverter.

BMS internal failure ⚠ Internal error — firmware or hardware
The battery's BMS has reported an internal fault. This is a well-known issue on early US3000C firmware versions (below V1.7) and US5000 firmware (below V2.8). Check your firmware version through BatteryView or your inverter's battery info page. If the firmware is outdated, a Pylontech-authorised installer can update it. If the firmware is current and the fault persists, the BMS board may need replacement under warranty. US-series faults guide →
Early charge cutoff (80–85%) Not reaching 100% · BMS limiting
The battery consistently stops charging at 80–85% instead of reaching 100%. This is typically caused by cell imbalance — one cell reaches the overvoltage threshold while others still have capacity. The BMS caps charge to protect the highest cell. Enable the battery's internal cell balancing by keeping it at a high SOC overnight periodically. Also check the inverter's charge voltage is set to Pylontech's recommended value and is not set for lead-acid profiles.
SOC stuck or inaccurate Display shows wrong % · SOC drift
The reported SOC does not match the battery's actual charge level — it may jump between values, stay stuck at one number, or show 100% when the battery is clearly not full. SOC drift occurs over time when the battery has not completed a full charge cycle. Perform a full charge to 100% and leave it at 100% for 2–3 hours to allow the BMS to recalibrate its SOC counter. If SOC remains inaccurate after calibration, a firmware update may resolve the issue.
Mixed stack capacity mismatch Different models in one stack
Stacking different Pylontech models (e.g. US3000C with US5000) is not officially supported and causes capacity and voltage mismatches. The smaller module reaches its limits before the larger one, triggering protection events and reducing usable capacity. If you have mixed models, separate them into independent stacks each connected to the inverter individually, or replace the mismatched unit.
Fault not listed here?

Pylontech faults often appear differently depending on which inverter brand is paired with the battery. If you're seeing an alarm in your inverter's monitoring that you can't match to this list, share the exact alarm text and your inverter brand and we'll identify it. Retrieving the Pylontech log files via BatteryView is the fastest route to a definitive diagnosis.

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FAQ

Pylontech battery fault questions

Pylontech batteries do not display numbered fault codes on a screen. Instead, they use LED indicators on the front panel. The ALM LED flashing red means a warning condition — the battery is approaching an operational limit but still working. The ALM LED solid red with all other LEDs off means protection mode — the battery has shut down. The specific fault type is identified through your paired inverter's monitoring platform or by connecting via Pylontech BatteryView software over the console port.
A flashing red ALM light means the battery is in an alarm state — a parameter like temperature, voltage, or current is approaching its limit but the battery continues operating. A solid red ALM light with all other LEDs off means protection mode — the BMS has shut down charge and discharge. Common triggers include cell overvoltage from overcharging, cell undervoltage from deep discharge, high temperature in an enclosed space, or a communication fault. Check your inverter's alarm log for the specific type.
Switch off the battery using the breaker or power button, wait at least 60 seconds, then switch it back on. If the battery entered protection due to low voltage, you may need to charge it from the inverter's AC supply before it will resume. If the battery shows 0V or will not power on, it may be in deep sleep protection and require a controlled bench recharge. If the same protection event triggers repeatedly after reset, the underlying cause needs professional diagnosis — do not keep resetting without investigating.
STS offers remote diagnostic assessments from free. Pylontech batteries log detailed operating data including cell voltages, temperatures, and alarm history. Our engineers can analyse this data remotely through your inverter's monitoring platform to identify the root cause and recommend the fix — whether that is a settings change, a firmware update, or a physical inspection.
Battery communication faults are the most common Pylontech issue. The inverter cannot talk to the battery BMS over CAN or RS485. Common causes include the cable plugged into the wrong port on the inverter, incorrect cable wiring (many supplied cables have the wrong pinout for your inverter brand), the battery not set as master in a multi-unit stack, or the wrong battery protocol selected in the inverter settings. Check the cable, port, and inverter battery type setting first. See our inverter pairing guide for brand-specific wiring.
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Battery alarm you can't clear?

Describe the LED state on the battery, what your inverter's monitoring is showing, and when the fault first appeared. We'll analyse the data remotely and tell you whether it needs a settings change, firmware update, or site visit.

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