GivEnergy CAN Communication Fault — Diagnostic Guide
Your GivEnergy inverter has lost communication with the battery over the CAN bus. The system may show STORAGE_WARN_BMS_COM_FAIL or STORAGE_ERROR_BMS_COM_FAIL — or simply show the battery as disconnected. This guide covers every cause in order of likelihood.
Jump to cause
The exact sequence of events in your inverter's log — what codes appeared, in what order, and when — tells us whether this is a cable fault, firmware issue, or BMS protection event. We can review this remotely.
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Controller Area Network
CAN bus is the communication protocol GivEnergy uses between the inverter and battery. It carries state of charge data, charge/discharge commands, temperature readings, and protection signals. Without it, the inverter cannot safely operate the battery.
The data link, not the battery
A CAN fault doesn't necessarily mean the battery is damaged. It means the communication channel has been interrupted. The battery cells themselves are usually fine — the system just can't talk to them. This distinction matters for whether the fix is remote or on-site.
Fault codes in the portal
The portal event log will show STORAGE_WARN_BMS_COM_FAIL (warning level) or STORAGE_ERROR_BMS_COM_FAIL (error level). The battery may show as disconnected in the portal dashboard, with SoC reading zero or N/A.
Before anything else — check these
Two checks that take under a minute and eliminate the most common causes immediately.
The GivEnergy battery has a power button on the side panel. If this has been accidentally turned off — after a power cut, during a house move, or by a household member — the battery will appear as disconnected and trigger a CAN fault. Press and hold the button until you hear a beep and the LED indicators illuminate.
The CAN communication cable runs between a socket on the inverter (underside) and a socket on the battery (typically labelled BMS or CAN). Check that the connector is fully seated at both ends — it should click firmly into place. A partially connected cable is a common cause of intermittent CAN faults, particularly on newer installations where cables may not have been fully seated at commissioning.
Restart the inverter and battery
Many CAN faults — particularly those triggered by power interruptions, brief grid outages, or software glitches — clear themselves after a controlled restart of both the inverter and battery. This should always be the first active step after the quick checks above.
Find the green or red handled MCB switch between the inverter and battery. Move it to the DOWN / OFF position. This isolates DC power between the two units before shutdown.
Press and hold the button on the side of the battery until the LEDs go out. The battery is now off. Leave it off for at least 60 seconds — this allows the BMS capacitors to discharge and clears any latched fault states.
The AC isolator is the switch below the inverter on the wall. Turn this off. Wait 60 seconds. Both the inverter and battery are now fully powered down.
Turn the AC isolator back on first. The inverter will begin its startup sequence. Then turn the battery on using the side button — wait for the LED indicators to stabilise (typically green). Then move the DC MCB back to the UP / ON position.
BMS_COM_FAIL code has cleared. If the fault reappears within minutes of restarting, there is a persistent underlying cause — continue through this guide.
CAN cable fault — loose, damaged, or wrong polarity
If the power cycle doesn't resolve the fault, the CAN cable between the inverter and battery is the next suspect. This is a physical cable and physical faults require a site visit to rectify — but a remote diagnostic can confirm the cable is the likely cause first.
Common cable fault types
Signs pointing to a cable fault
Firmware mismatch between inverter and battery
The GivEnergy inverter and battery run separate firmware versions that must be compatible with each other. If the inverter firmware is updated but the battery firmware isn't — or vice versa — the CAN protocol version can become incompatible and communication breaks.
How to check firmware versions
Go to givenergy.cloud → My Inverter → Software. The current firmware version is shown here. GivEnergy will also show whether an update is available for the inverter.
Battery firmware version is visible in the portal under My Inverter → Battery details. If the battery firmware shows as outdated or mismatched, it needs updating. Check the GivEnergy knowledge base for the firmware compatibility matrix for your models.
Remote firmware update (inverter)
If the inverter firmware needs updating, this can be done remotely via the portal. Go to My Inverter → Software and click Update if an update is available. The update takes 5–30 minutes — do not turn the system off during this process. If the update appears stuck after an hour, restart the inverter.
Battery firmware update (requires USB — installer task)
Battery firmware updates are done locally via a USB stick inserted into the battery's internal USB port. This requires opening the front cover of the battery, which is an installer task — do not attempt this yourself. Contact GivEnergy support to obtain the correct BMS_ARM.bin file and arrange for an engineer visit if a battery firmware update is required.
BMS protection event — battery locked itself out
The Battery Management System (BMS) can lock the battery into a protection state in response to events like over-voltage, under-voltage, over-temperature, or a short-circuit detection. When locked in a protection state, the BMS stops responding to the inverter's CAN requests — which is reported as a communication fault even though the cable is fine.
What triggers a BMS lockout
Identifying a BMS lockout vs a cable fault
Recovery from BMS lockout
Some BMS protection events clear themselves after a controlled power cycle (see the power cycle section above). Others — particularly over-discharge events — require the battery to be recovered with a slow charge before the BMS will accept normal operation. Contact GivEnergy support if a power cycle doesn't clear the fault and a BMS protection event is suspected.
See the red light / battery alarm guide →Hardware fault — inverter CAN port or battery BMS board
If all the above have been checked and ruled out, the fault may be a hardware failure — either the CAN interface on the inverter, or the BMS board inside the battery. These are warranty-eligible repairs on systems within the manufacturer warranty period.
Inverter CAN port failure
The CAN transceiver on the inverter PCB can fail — particularly after lightning-induced surges or sustained over-voltage events. Signs include persistent BMS_COM_FAIL with a known-good cable, and the fault appearing on a new battery if the battery is swapped as a test.
GivEnergy inverter warranty: typically 5–10 years depending on model. Contact GivEnergy with a written diagnostic report to support a warranty claim.
Battery BMS board failure
The BMS board inside the battery can fail independently of the battery cells. This is a hardware fault inside the enclosure and requires an engineer visit. Do not open the battery yourself. Battery warranty is typically 5–10 years and covers BMS hardware failures.
A remote diagnostic and written engineer report identifying the fault strengthens any GivEnergy warranty claim significantly.
A written engineer report identifying the fault type and cause significantly strengthens GivEnergy warranty submissions. We can provide this as part of a remote diagnostic session.
Battery alarm states and what each flash pattern means.
Firmware updates causing new faults or resetting settings.
Battery not charging overnight — system mode and CT clamp causes.
Full index of GivEnergy fault codes and their meanings.
GivEnergy CAN fault questions
STORAGE_WARN_BMS_COM_FAIL is a warning-level code — the system has detected a communication issue but hasn't entered a full error state yet. The battery may still be operating but with reduced confidence. Try the power cycle first. STORAGE_ERROR_BMS_COM_FAIL is the error-level equivalent, indicating the communication has been fully lost. Both codes point to the same root causes — the error version simply means the fault has persisted or is more severe.
Yes — solar generation is typically unaffected by a CAN communication fault. The panels and inverter continue to generate and export or supply the house. What stops is battery charging and discharging — the inverter cannot safely control the battery without the CAN link. Your solar generation figures in the portal should still be accurate even during a CAN fault.
An intermittent CAN fault that clears after restart but returns within hours or days typically points to either a marginally connected cable (partially seated connector that vibrates loose), a firmware incompatibility where the inverter and battery negotiate successfully on startup but lose sync during operation, or an intermittent BMS protection event triggering repeatedly. A remote diagnostic reviewing your event log over the past week can identify the pattern and narrow the cause.
In a multi-battery stack, each battery has its own BMS and CAN connection in a daisy-chain. If one battery has a CAN fault while others are fine, the fault is localised to that unit — its cable connection, its own BMS firmware, or a hardware fault on that specific battery. Check the CAN cable connection at both ends of the affected unit specifically. Also check its firmware version — it may need updating independently of the others.
Still showing a CAN fault? We'll diagnose it.
Tell us what the portal shows, when the fault appeared, and what you've already tried. We'll review your event log and identify whether this is a cable, firmware, BMS, or hardware fault — before recommending any site visit.
This is a brand-specific version of our general battery communication fault guide, which covers all brands.