Sungold Power Hybrid Inverter plus Victron SmartSolar MPPT250/60 connect to Ecoworthy Cubix 100 Fault

Had a similar headache last year mixing kit from different brands — the gremlin is almost always in the comms or charge profile settings rather than the hardware itself.

Few things worth checking:

• BMS communication — is the Cubix 100 actually talking to either device, or is it running in standalone mode? Ecoworthy's BMS can be a bit fussy about which protocol it'll handshake with
• Charge voltage conflict — if both the Sungold and the Victron MPPT are set to push charge parameters independently, they can fight each other. The MPPT should ideally be the "dumb" unit deferring to the inverter, or you need proper DVCC sorted
• Victron VictronConnect app — worth pulling the MPPT logs to see if it's throwing any errors or throttling itself back

On my setup I've got a Fogstar Drift 200Ah paired with a Victron SmartSolar and it took a fair bit of fiddling to get the absorption/float voltages dialled in properly so nothing was stressing the BMS.

What exactly is the fault showing? Is it on the inverter display, the MPPT, or are you getting a BMS cutoff? That'll narrow it down massively.

Also — have you got the Victron wired through the inverter's PV input or straight to the battery? Depending on the Sungold model that could be the root cause entirely.

Others on here have dealt with Ecoworthy integration before — hopefully someone with that specific Cubix model can chime in too.

@MidlandsNomad spot on about the charge profiles — that's exactly what caught me out with my cabin setup running a Victron SmartSolar alongside third-party kit.

The Ecoworthy Cubix 100 is a LiFePO4 battery, so make sure your MPPT is set to the correct lithium profile. Default absorption voltage out of the box is often set for AGM, and that mismatch alone can trigger all sorts of protection faults on the BMS side.

Also worth checking:

• MPPT tail current settings — the Victron can confuse the Cubix BMS if it's dithering in absorption too long
• Shared negative/ground between all three units — floating grounds cause phantom faults constantly
• What does the Victron Connect app actually show as the fault state? That'll narrow it down sharpish.

@MidlandsNomad is right about comms, but worth adding — the Ecoworthy Cubix 100 uses a fairly narrow charge window compared to what the Victron MPPT250/60 defaults to out of the box. If your absorption voltage is set even 0.2V too high, the BMS in that battery will hard-disconnect and the inverter throws a fault code that looks hardware-related but isn't.

On my shepherd's hut build I had the exact same phantom fault. Fixed it by setting a custom charge profile on the Victron (via VictronConnect) rather than using the LiFePO4 preset:

• Absorption: 14.2V
• Float: 13.5V
• Tail current: 2A

Also double-check the Sungold's own charging parameters aren't fighting the MPPT — if both are actively trying to charge simultaneously without proper load-sharing coordination, the Cubix BMS will trip repeatedly. Isolate one source temporarily to confirm which is causing the conflict.

Good shout from @MidlandsNomad and @Macca. One thing I'd add that caught me out with a similar mixed setup — double-check the absorption voltage ceiling on the Sungold hybrid side isn't clashing with what the Victron MPPT is trying to push. When both units think they're in charge, you can get them effectively arguing over the battery, which confuses the Cubix's BMS something rotten.

If the Cubix has a CAN bus port, try disabling the Victron's standalone charging profile entirely and let the Sungold take master control via the BMS comms. The Victron then just becomes a dumb power source feeding the Sungold rather than independently managing charge stages. Made a massive difference on my setup. Worth having a dig through the Victron VictronConnect app and setting it to "external control" mode.

@LesWood78 makes a good point about the Cubix charge window — worth noting the BMS comms on that unit can also be a bit fussy about which protocol you're using. Had something similar on my static caravan setup where the Victron MPPT was defaulting to its own lithium preset rather than taking instructions via the BMS.

If you've got VictronConnect handy, check whether the MPPT is set to "BMS controlled" or running a standalone charge profile. If it's standalone, your absorption voltage could easily be pushing outside what the Cubix tolerates.

Also worth double-checking your battery cable sizing — undersized cables cause voltage drop that confuses both units into thinking something's wrong when it isn't.