Hi all

I've tried the search function but couldn't quite find something that matches my issue.

I have a Growatt SPF 5000ES inverter connected to x4 Dyness B4850 batteries via RS485 (comms by CAN protocol L52) - no issues in this setup. I have since acquired x2 more B4850s secondhand and they don't appear to playing well together as a stack even after they been top-balanced. The x2 purchased recently have a visual difference to the x4 older batteries, in that they have x5 SOC lights on the panel in comparison to the x4 SOC lights on my original quad.

When connected to my current system (with one of my original older batteries as the Master), the x2 "newer" batteries show all SOC and RUN lights flashing - which according to the handbook denotes a communication fault.

Additionally, I can run the x2 newer batteries on their own just fine. If I set one of the "newer" batteries as the master for all x6 in a stack, the SOC lights for the "older" x4 batteries are out of sync and show varying SOC indications

Any ideas? I presume they can be used together as they are the same model but I'm unsure if they have differences in internals or software (and unclear whether consumers can flash firmware updates).

Any help would be much appreciated.

Hi there,I see you're having communication issues with your Dyness B4850 setup these are very common, especially when mixing batteries of different ages or batches. One strong possibility is a firmware mismatch between the batteries (or between the batteries and your inverter). The B4850 modules have BMS firmware that needs to be compatible across the whole bank. When you add older or used units to newer ones, the versions often don't line up, causing comms faults as soon as the full system tries to talk together.

Quick checks first (do these before jumping to firmware)

• Double-check DIP switch addresses every battery must have a unique ID. Master usually on a specific setting, slaves different.

• Confirm you're using the correct CAN cable and pinout for your inverter brand.

• Set the inverter to the proper Dyness (or closest compatible) battery type.

• Power cycle: Batteries first (master then slaves), wait, then inverter.

If those are all good and the fault only appears when the full bank is connected, firmware is the likely culprit.

Firmware Update RouteDyness doesn't make the files publicly easy to find, and direct support can be slow.

Many users in similar situations have successfully updated by:

• Contacting their battery supplier/installer for the matching firmware files.

• Using Dyness-specific monitoring software + a proper CAN/RS232 adapter cable to flash the BMS.

In cases where batteries came from different batches, bringing everything to the same firmware version has resolved comms errors.

If you can share:

• Your inverter model + exact error code

• How many B4850 units and whether they’re all the same age/batch

• DIP switch photos or settings

...we can narrow it down further.In the meantime, try running just the “problem” batteries as a small separate bank to confirm they work on their own.

That helps isolate whether it’s truly a version mismatch.

34 minutes ago, Powerforum Store said:

Hi there,I see you're having communication issues with your Dyness B4850 setup these are very common, especially when mixing batteries of different ages or batches. One strong possibility is a firmware mismatch between the batteries (or between the batteries and your inverter). The B4850 modules have BMS firmware that needs to be compatible across the whole bank. When you add older or used units to newer ones, the versions often don't line up, causing comms faults as soon as the full system tries to talk together.

Quick checks first (do these before jumping to firmware)

• Double-check DIP switch addresses every battery must have a unique ID. Master usually on a specific setting, slaves different.

• Confirm you're using the correct CAN cable and pinout for your inverter brand.

• Set the inverter to the proper Dyness (or closest compatible) battery type.

• Power cycle: Batteries first (master then slaves), wait, then inverter.

If those are all good and the fault only appears when the full bank is connected, firmware is the likely culprit.

Firmware Update RouteDyness doesn't make the files publicly easy to find, and direct support can be slow.

Many users in similar situations have successfully updated by:

• Contacting their battery supplier/installer for the matching firmware files.

• Using Dyness-specific monitoring software + a proper CAN/RS232 adapter cable to flash the BMS.

In cases where batteries came from different batches, bringing everything to the same firmware version has resolved comms errors.

If you can share:

• Your inverter model + exact error code

• How many B4850 units and whether they’re all the same age/batch

• DIP switch photos or settings

...we can narrow it down further.In the meantime, try running just the “problem” batteries as a small separate bank to confirm they work on their own.

That helps isolate whether it’s truly a version mismatch.

Thanks so much for the quick reply.

I can confirm that I am able to run the 'problem' batteries (the x2 latest I have acquired) on their own with no faults.

Further info as requested:

• No error code on the inverter (Growatt SPF 5000ES)

• x6 B4850s (x4 from 2022, x2 from 2023 - could provide S/Ns if helpful)

• DIP switch settings are x1 2022 battery set to Master with 0010, all other x5 slaves (x3 2022 & x2 2023) all set to 0000.

Noted that you've advised to set unique IDs but I've been unable to find any guidance on what to set the slaves to for this setup. Do they just have to be all different? If so, how do I determine the Master?

Thanks again!