Deye SUN Hybrid F58 — BMS Communication Fault (Battery Comms Lost)

What it means: The inverter has lost its data link to the battery's BMS. Deye's manuals describe F58 as "BMS communication fault" and explain that it reports the communication between the hybrid inverter and the battery BMS being disconnected while the "BMS_Err-Stop" setting is active. Nothing has necessarily failed inside the battery — but the inverter can no longer be told by the pack how much charge it will accept, how much it will give, or when to stop. It has halted rather than guess.

Why does Deye show F58?

The Pakistan factor

This is where Pakistan's battery market collides with Deye's documentation. Deye's approved list runs to roughly 120 brands and clears the mainstream 48 V names — it lists Pylontech (entered as "PYLON", covering the US2000/US3000, UP5000/US5000 and Force L1/L2 families), plus Dyness, Narada, BYD, Weco, Fox ESS, Livoltek and Soluna packs. The house brands a Pakistani installer is most likely to put in the same rack — Knox, Osaka Lithium, Fronus, Vaults, Dongjin — are not on it. A pack that is electrically fine and simply does not speak the protocol will sit there throwing F58 forever, and no amount of cable swapping will change that. The dangerous local shortcut is the one Deye's own manual hands people: switch off BMS_Err-Stop, the error goes away, the customer is happy, and the installer leaves an unapproved lithium bank being charged by an inverter that has been told to ignore it. Combine that with Pakistani summer heat and a rack in an unventilated store room and you have the standard precondition for a lithium fire. If a technician offers to turn off BMS_Err-Stop as the fix, that is the moment to get a second opinion. Ask instead which line of DY-LV48-0121 your battery appears on — if the answer is none, the problem is the pairing, not the setting.

How to fix it

  1. Note the exact wording and check the battery's own display or app. If the pack still reports a healthy voltage and state of charge to itself, this is a communication problem, not a battery failure — which is good news and changes who you call.
  2. Check whether anything moved. F58 that starts the day after an installer visit, a pack was added, or the rack was tidied is almost always the comms lead. Look at the cable between battery and inverter for an obviously unseated or crushed RJ45. Looking is fine; re-terminating is not.
  3. Do not "fix" F58 by turning off BMS_Err-Stop. Deye's manual does list disabling the "BMS_Err-Stop" item on the LCD as a way to stop seeing this happen, and that line gets quoted locally as a solution. It is not one. Disabling it does not restore communication — it only stops the inverter from halting when communication is lost, so it goes on charging and discharging your lithium pack blind, on its own voltage settings, with no BMS telling it when to stop. The protection is there because a lithium pack that is charged past its limit is a fire, not an inconvenience. Only change that setting on a qualified engineer's instruction and only as a temporary measure while a fault is being diagnosed.
  4. Do not open the battery, do not remove a pack from a live rack, and do not swap comms leads between packs to see what happens. Lithium packs are live at their terminals whatever the inverter is doing.
  5. Qualified installer, from here. He should confirm the physical port (CAN vs RS485), the cable pinout, the protocol and lithium-mode setup number on the inverter, and the DIP switch or address settings on each pack. Getting a rack of packs to agree on who is master is a five-minute job for someone who has done it and an afternoon for someone who has not.
  6. Check the pack against Deye's approved battery list. Deye publishes a versioned list (DY-LV48-0121, issued 25 February 2026) giving each approved pack its interface and its lithium-mode setup number, and states there that "the purchaser should confirm with the battery supplier if the battery is compatible with Deye inverter, or Deye will not be liable for any failure that caused by communication issue". If your pack is not on that list, F58 may not be fixable by settings at all, and the conversation is with the battery supplier.
  7. If the cable, ports, protocol and addressing are all correct and F58 persists, Deye's manual ends at "if the fault still exists, please contact us for help" — the fault is in the inverter's comms port or the BMS itself, and that is a service job for whichever manufacturer's part is at fault.

References